JP6789658B2 - Light source device and information acquisition device using it - Google Patents

Description

The present invention relates to a light source device using a nonlinear optical effect and an information acquisition device using the same.

In recent years, an imaging technique that irradiates a measurement target with pulsed light and uses a nonlinear optical effect generated in the measurement target has been actively studied. Imaging using a nonlinear optical effect makes it possible to identify substances inside the measurement target without staining, and to perform imaging with high resolution exceeding the optical diffraction limit. In order to obtain high-sensitivity spectroscopic imaging over a wide band, a high-power light source capable of variably controlling the wavelength over a wide band is required.

For a wideband light source, a nonlinear wavelength conversion technique has been developed in which an optical waveguide and a short pulse light source are combined to convert a wavelength by a nonlinear optical effect generated in the optical waveguide. When the short pulse light propagates through the optical waveguide, the short pulse light has a high peak power and the cross-sectional area of the optical waveguide is small, so that the short pulse light is optical in a state where a large amount of light energy is concentrated in a very small area. Propagate the waveguide. This large light energy density induces a nonlinear optical phenomenon, and the wavelength and time shape of the propagating light pulsed light change. As such a nonlinear wavelength conversion technique, a technique has been proposed in which the wavelength of pulsed light input to an optical waveguide is widened or the center wavelength is shifted by using the Kerr effect, Raman effect, and parametric effect (Non-Patent Document 1, Non-Patent Document 1, 2).

Non-Patent Document 1 describes an all-optical signal control technique based on pulse trapping in a birefringent fiber and amplification by an ultrashort soliton pulse.
In addition, Non-Patent Document 2 describes a synchronously excited fiber optical parametric oscillator that operates in a normal dispersion region.

“Ultrafast all-optical signal regenerator using pulse trapping in birefringent fibers”, Eiji Shiraki, Norihiko Nishizawa, and Kazuyoshi Itoh, J. Opt. Soc. Am. B, Vol. 28, No. 11, pp. 2643 (2011) “Normal dispersion femtosecond fiber optical parametric oscillator”, T. N. Nguyen, K. Kieu, A. V. Maslov, M. Miyawaki, and N. Peyghambarian. Optics Letters, Vol. 38, Issue 18, pp. 3616-3619 (2013)

However, the technique described in Non-Patent Document 1 is limited to wavelength conversion to a long wavelength because it utilizes a soliton shift. Moreover, since the pump pulse light must be a soliton pulse light, the power of the input pump pulse light is limited. Therefore, it has been difficult to increase the output.

On the other hand, in the technique described in Non-Patent Document 2, the wavelength tunable band of pump pulse light is limited. Therefore, it has been difficult to extend the parametric gain band. Further, due to the difference in the group velocity between the pump pulse light and the signal pulse light, the interaction length is limited, the energy conversion efficiency is reduced, and it is difficult to increase the output.

An object of the present invention is to provide a light source device capable of realizing a wide band of a tunable wavelength band and a high light output, and an information acquisition device using the light source device.

According to one aspect of the present invention, the first light source that outputs the first light, the second light source that outputs the second light having a wavelength different from that of the first light, and the first light source. An optical combining unit that combines light and the second light, and the first light and the second light combined by the optical combining unit are input, and the first light is input by an optical parametric effect. It has a non-linear optical waveguide in which energy is transferred from light to the second light, and the non-linear optical waveguide has at least two or more propagation axes having different propagation constants, the first light and the first light. Provided is a light source device characterized in that the light of 2 propagates on the propagation axis having different propagation constants.

According to another aspect of the present invention, the subject is irradiated with two pulsed lights having different center wavelengths, and the light reflected by the subject, the light transmitted through the subject, and the light emitted by the subject are emitted. An information acquisition device that detects at least one of light and acquires information about the subject, and is reflected by the subject and a light source that emits two pulsed lights with different center wavelengths. Of two pulsed lights having a light receiving portion that receives at least one of light, light transmitted through the subject, and light emitted from the subject, and the light source portion having different central wavelengths from each other. An information acquisition device is provided, which comprises the above-mentioned light source device that outputs at least one of the light sources.

According to the present invention, it is possible to realize a wide band of a tunable wavelength band and a high optical output.

It is a figure explaining the example of the basic structure of the light source device by this invention. It is a figure explaining the light source apparatus by 1st Embodiment of this invention. It is a graph which shows the effective refractive index curve of the nonlinear optical waveguide used in the light source apparatus by 1st Embodiment of this invention. It is a graph which shows the center wavelength of the parametric gain spectrum with respect to the pump pulse light wavelength in the light source apparatus by 1st and 5th Embodiment of this invention. It is a figure explaining the light source apparatus by 2nd Embodiment of this invention. In the light source device according to the third embodiment of the present invention, the center wavelength of the parametric gain spectrum with respect to the pump pulse light wavelength and the wavelength at which the pump pulse light wavelength and the group velocity match in the Fast axis orthogonal to the Slow axis of the optical waveguide. It is a graph which shows. In the light source device according to the seventh embodiment of the present invention, the center wavelength of the parametric gain spectrum with respect to the pump pulse light wavelength and the wavelength at which the pump pulse light wavelength and the group velocity match in the Fast axis orthogonal to the Slow axis of the optical waveguide. It is a graph which shows. It is a graph which shows the effective refractive index curve of the nonlinear optical waveguide used in the light source apparatus by the 9th Embodiment of this invention. It is a graph which shows the center wavelength of the parametric gain spectrum with respect to the pump pulse light wavelength in the light source apparatus by the 9th and 13th Embodiment of this invention. In the light source device according to the eleventh embodiment of the present invention, the wavelength at which the pump pulse light wavelength and the group velocity match on the center wavelength of the parametric gain spectrum with respect to the pump pulse light wavelength and the Fast axis orthogonal to the Slow axis of the optical waveguide. It is a graph which shows. It is a figure explaining the light source apparatus by 19th Embodiment of this invention. It is a figure explaining the light source apparatus by 20th Embodiment of this invention. It is a figure explaining the light source apparatus by 21st Embodiment of this invention. It is a figure explaining the light source apparatus by 22nd Embodiment of this invention. It is a figure explaining the light source apparatus by 24th Embodiment of this invention. It is a figure explaining the light source apparatus by the 25th Embodiment of this invention. It is a figure explaining the light source apparatus by the 26th Embodiment of this invention. It is a figure explaining the information acquisition apparatus by the 28th Embodiment of this invention. It is a figure explaining the information acquisition apparatus by the 29th Embodiment of this invention.

[Basic configuration of the present invention]
Prior to explaining the embodiment of the present invention, an example of the basic configuration of the present invention and related phenomena will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of a basic configuration of a light source device according to the present invention.

As shown in FIG. 1, the light source device according to the present invention has a pump pulse light source 101 that outputs pump pulse light and a parametric gain medium 103. The parametric gain medium 103 is a medium that amplifies signal pulsed light (or idler pulsed light) having a wavelength different from that of pump pulsed light due to an optical parametric effect. In the present specification, in the parametric gain band generated by the pump pulse light in the parametric gain medium, the short wavelength side is called signal light, the long wavelength side is called idler light, and the short wavelength side is referred to as pulsed light. The signal pulse light and the long wavelength side are called idler pulse light. Also, the parametric gain medium has at least two or more different polarization axes. The parametric gain medium is more specifically a non-linear optical waveguide such as a non-linear optical fiber.

The signal pulsed light (or idler pulsed light) may be generated by the parametric gain medium 103 due to the parametric effect, or is combined with the pump pulsed light from an external light source and input to the parametric gain medium 103. It may be a thing. When the signal pulsed light (or idler pulsed light) is input from the outside, the light source device according to the present invention uses a signal pulsed light source 106 that outputs a signal pulsed light (or idler pulsed light) having a wavelength different from that of the pump pulsed light. Have. Further, in this case, the light source device according to the present invention combines the pump pulse light output from the pump pulse light source 101 and the signal pulse light output from the signal pulse light source 106 and inputs them to the parametric gain medium 103, for example. It has an optical combining unit 102 that is an optical combining element.

The pump pulse light 104 having an optical angular frequency ω ₁ output from the pump pulse light source 101 propagates through the optical combiner 102 and is incident on the parametric gain medium 103. Further, a signal pulsed light 105 having an optical angular frequency ω _S (a signal pulsed light having an optical angular frequency ω ₃ or an idler pulsed light having an optical angular frequency ω ₄ ) is incident on the parametric gain medium 103 via the optical combiner 102. Will be done. At this time, the pump pulse light 104 and the signal pulse light 105 are incident in a state where the polarization is adjusted so as to propagate the different propagation axes of the parametric gain medium 103. Further, the pump pulse light 104 and the signal pulse light 105 are adjusted so as to overlap each other in time and are incident. That is, the pump pulse light 104 and the signal pulse light 105 are combined by the optical combine unit 102 and input to the parametric gain medium 103.

ここで、ωは光角周波数、ｎ（ω）は光導波路の有効屈折率、ｃは真空中の光速を表わす。つまり、波長分散β（ω）は、光角周波数ωの光が光導波路を１ｍ伝搬した際に、どれだけの位相ずれを生じるかを意味している。 Here, first, the wavelength dispersion will be described. The optical waveguide that propagates light has a refractive index possessed by a substance constituting the optical waveguide and a wavelength dispersion determined by the structure of the optical waveguide. The wavelength dispersion β (ω) is defined by the following mathematical formula (1).

Here, ω represents the optical angular frequency, n (ω) represents the effective refractive index of the optical waveguide, and c represents the speed of light in vacuum. That is, the wavelength dispersion β (ω) means how much phase shift occurs when light having an optical angular frequency ω propagates through the optical waveguide for 1 m.

By Taylor-expanding the above mathematical formula (1), the following mathematical formula (2) is obtained.

Here, ω ₀ is the central optical angle frequency of the Taylor expansion. The first-order dispersion β ₁ (ω) represents the reciprocal of the group velocity and is related to the propagation velocity of the pulsed light in the optical waveguide when the central optical angular frequency of the pulsed light is ω. Further, β ₂ (ω), which is a secondary variance, means the temporal spread of the propagating pulsed light in the optical waveguide.

When the diameter of the optical waveguide changes along the propagation direction of light, or when the density or constituent material changes, the refractive index felt by the propagating light changes depending on the polarization of the propagating light. For example, in a medium having birefringence, the refractive index n differs along the axis of birefringence. A medium having birefringence is said to have two propagation axes, a phase-advancing axis and a slow-phase axis. Therefore, the dispersion β also differs depending on the birefringence axis.

Next, the optical parametric effect will be described.
In the present invention, optical amplification is performed by energy transition due to the optical parametric effect.

The generation of gain due to the optical parametric effect is based on four-wave mixing. When a laser beam is incident on a medium, polarization occurs due to an electronic response in the medium with respect to the incident laser light. When the intensity of the incident laser light increases and the electric field intensity increases, the polarization due to the electronic response becomes non-linear with respect to the incident laser light. The non-linear polarization that occurs at this time produces light with a wavelength different from that of the incident laser light. In a medium having inverse symmetry such as an optical fiber, the non-linear susceptibility of even-order order becomes zero, so that the non-linear effect due to the non-linear susceptibility of odd-order order appears. In particular, the value of the third-order nonlinear susceptibility χ ⁽³⁾ is large, which gives a major polarization / nonlinear effect. Four-wave mixing is explained by a third-order nonlinear susceptibility. Hereinafter, the propagation direction of the laser is defined as the z-axis direction. The third-order polarization P _xxx ⁽³⁾ in the x-axis direction caused by the laser electric field in the x-axis direction is expressed by the following mathematical formula (3) using the dielectric constant ε ₀ , with the direction orthogonal to the z-axis as the x-axis. Is done.

At this time, the incident laser electric field _Ex is expressed by the following mathematical formula (4) as the sum of the laser electric fields of _three different optical angular frequencies ω ₁ , ω ₂ , and ω ₃ .

Here, β (ω ₁ ), β (ω ₂ ), and β (ω ₃ ) are propagation constants of light having components of optical angular frequencies ω ₁ , ω ₂ , and ω ₃ , respectively. In addition, c. c. Represents the complex conjugate of all light before it.

つまり、３つの異なる光角周波数ω_１、ω_２、ω_３のレーザー光を入力することで、これらとは異なる光角周波数ω_４を有する光が発生されることを意味している。 In P _xxxx ⁽³⁾ , the term of the vibration component having the optical angular frequency ω ₄ = ω ₁ + ω ₂ -ω ₃ appears as shown in the following mathematical formula (5).

That is, it means that by inputting laser light having _three different optical angular frequencies ω ₁ , ω ₂ and ω ₃ , light having an optical angular frequency ω ₄ different from these is generated.

In order to output the laser light having the optical angular frequency ω ₄ , it is necessary that the signal lights generated at each point in the medium are strengthened. This condition is expressed by the following mathematical formula (6) and is called a phase matching condition.

Further, since phase modulation occurs due to the nonlinear optical effect, the phase matching condition can be expressed by the following mathematical formula (7).

Here, when ω ₁ = ω ₂ , that is, when the wavelength of the incident pump pulse light is one, it is called degenerate four-wave mixing, and even in that case, the optical parametric effect occurs, and the mathematical formula (7) is rewritten. , The following formula (8) is obtained.

Even when only pump pulsed light is input to the medium, laser light having optical angular frequencies of ω ₃ and ω ₄ can be generated (optical parametric generation, Optical Parametric Generator; OPG).

Also in degenerate four-wave mixing, the omega ₁ simultaneously omega ₃ and the pump pulse light having optical angular frequency when incident signal light having an optical angular frequency, the light having an optical angular frequency of omega ₁ of omega ₃ An energy transition occurs to light with an angular frequency. An optical amplifier using such a phenomenon is called an optical parametric amplifier (OPA). A similar energy transition occurs when idler light having an optical angular frequency of ω ₄ is incident instead of the signal light.

Further, by forming a resonator with OPA as a gain, it is possible to amplify and oscillate the parametric light. Such a resonator is called an optical parametric oscillator (OPO).

The parametric gain spectrum is expressed by the following mathematical formula (9) (“Fiber Optical Parametric Amplifiers, Oscillators and Related Devices”, Michel E. Marhic, Cambridge university press).

Here, g is expressed by the following mathematical formula (10).

L is the length of the optical waveguide. Further, γ represents the non-linear coefficient of the optical waveguide, and is determined by the non-linear refractive index n ₂ of the medium constituting the optical waveguide, the optical angular frequency ω, and the core diameter A _eff of the optical waveguide.

The following mathematical formula (11) is derived from the mathematical formulas (9) and (10).

The central light frequency of the parametric gain spectrum satisfies the following equation (12).

Δβ is calculated from the mathematical formula (6). In the following, Δω = | ω ₃ −ω ₁ | = | ω ₄ −ω ₁ |. When the polarization axes are the same, the mathematical formula (6) becomes the following mathematical formula (13).

In the present invention, the phase matching condition is extended to the case where the polarization axes of the pump pulse light and the signal light (or idler light) are orthogonal to each other. When the polarization axes are orthogonal, the following formula (14) is used.

Here, P and S represent propagation axes having different propagation constants of the optical waveguide. A polarization-holding optical fiber having polarization-holding characteristics has two axes, a Fast axis (phase advance axis) and a Slow axis (slow phase axis), as propagation axes having different propagation constants. The combination of P and S may be a combination of P being the Fast axis and S being the Slow axis, or P being the combination of the Slow axis and S being the combination of the Fast axis.

From equations (12) and (14), it is found that the wavelength band of parametric gain can be extended by 2 (β _P (ω ₁ ) -β _S (ω ₁ )), which is a term of variance of the 0th order. It was. This has never been shown in a wavelength conversion light source using an optical parametric effect as represented by Non-Patent Document 2. Therefore, in the present invention, the pump pulse light that gives the parametric gain and the signal pulse light that receives the parametric gain with different wavelengths from the pump pulse light are incident on the two propagation axes having different propagation constants. This makes it possible to change the parametric gain wavelength band in the present invention. By controlling the polarization of the pump pulse light and the signal pulse light in this way, a wide band parametric gain wavelength band can be obtained. Therefore, according to the present invention, it is possible to realize a wide band of the wavelength tunable band in the light source device.

Further, in parametric amplification using pulsed light, light having an optical angular frequency of ω ₁ and light having an optical angular frequency of ω ₃ (or ω ₄ ) must overlap in time. When both the pump pulsed light having an optical angular frequency of ω _{1 and} the signal light having an optical angular frequency of ω ₃ (or the idler light having an optical angular frequency of ω ₄ ) are pulsed lights, the propagation velocity is due to dispersion. The overlapping lengths (time) are limited because they are different. This is called the walkoff length. In the present invention, as described above, the pump pulse light that gives the parametric gain and the signal pulse light that receives the parametric gain with different wavelengths from the pump pulse light are incident on the propagation axes having different propagation constants. Further, the pump pulse light and the signal pulse light having the same group velocity and the corresponding parametric gain wavelength are combined. As a result, the parametric gain of the pump pulsed light can be increased, and the pulsed light can be propagated in a state of high intensity while being superimposed, and the energy conversion to the signal pulsed light can be increased. In the present invention, the propagation speed is matched by the difference in the birefringence axis to extend the interaction length, so that the signal pulsed light (or idler pulsed light) having a wavelength different from that of the pump pulsed light is increased in output by the optical parametric effect. It becomes possible to do. Therefore, according to the present invention, it is possible to realize a high light output in the light source device.

Even when idler pulsed light is used instead of signal pulsed light, it is possible to realize a wider band of the variable wavelength band and higher light output in the light source device in the same manner as in the case of signal pulsed light. ..

In general, in the nonlinear wavelength conversion technique, a high energy density is obtained by using pulsed light, and a high nonlinear optical effect is obtained. Further, the longer the interaction length between the pump pulse light serving as a pump and the signal pulse light that receives energy after wavelength conversion, the greater the nonlinear optical effect. In the nonlinear wavelength conversion technology using an optical fiber, the interaction length can be lengthened by the length of the optical fiber. However, due to the wavelength dispersion of the optical fiber, the propagation speeds of the pump pulse light and the signal pulse light having different wavelengths are different, and the peak position of the pulsed light shifts as it propagates, and as a result, the interaction length is limited.

Therefore, in Non-Patent Document 1, the interaction length is lengthened and the nonlinear optical effect is enhanced by using an optical fiber having a double refraction characteristic. Further, in Non-Patent Document 1, the wavelengths of the pump pulse light and the signal pulse light are shifted to longer wavelengths by utilizing the soliton shift. In such Non-Patent Document 1, a phenomenon called pulse trapping is caused by positively using cross phase modulation (XPM). In the pulse trapping that occurs in Non-Patent Document 1, pump pulse light that gives energy propagates in solitons. In such a case, the pump pulse light is incident in a pulse shape such that the soliton order N given by the following mathematical formula (15) is in the range of 0.5 <N <1.5.

Here, γ represents a non-linear coefficient, which is determined by the non-linear refractive index n ₂ of the medium constituting the optical waveguide, the optical angular frequency ω, and the core diameter A _eff of the optical waveguide. P ₀ represents the peak intensity of the pulsed light, _TFWHM represents the full width at half maximum of the pulsed light time, and β ₂ represents the secondary wavelength dispersion value of the optical waveguide with respect to the central wavelength of the pulsed light. In addition, the optical waveguide has anomalous dispersion characteristics. That is, β ₂ is a negative value.

Soliton propagation occurs by balancing anomalous dispersion with self-phase modulation (SPM), which is one of the nonlinear optical effects. Specifically, first, there is a phenomenon in which the long wavelength component in the pulsed light is shifted to the rear of the pulsed light and the short wavelength is shifted to the front of the pulsed light due to the anomalous dispersion. On the other hand, there is a phenomenon that the front part of the pulsed light has a longer wavelength and the rear part has a shorter wavelength due to SPM, and it can be said that this apparently gives normal dispersion. When these two phenomena are balanced and the pulsed light propagates while maintaining its shape, it is called soliton propagation.

Further, in pulse trapping, the signal pulsed light is captured by the XPM as the pump pulsed light. Specifically, first, it is assumed that the signal pulsed light has a wavelength slightly longer than the wavelength at which the group velocities match between different birefringence axes. In such a case, since the optical waveguide has anomalous dispersion, the signal pulsed light propagates later than the pump pulsed light. Then, the signal pulsed light is located behind the pump pulsed light. Therefore, the signal pulsed light has a shorter wavelength due to XPM and a faster propagation speed, and as a result, catches up with the pump pulsed light. On the other hand, it is assumed that the signal pulsed light has a wavelength slightly shorter than the wavelength at which the group velocities match between different birefringence axes. In such a case, the optical waveguide has anomalous dispersion, so that the signal pulsed light propagates faster than the pump pulsed light. Then, the signal pulsed light is located in front of the pump pulsed light. Therefore, the signal pulsed light has a longer wavelength due to XPM and the propagation speed becomes slower, and as a result, it can catch up with the pump pulsed light. When such a phenomenon continues to occur, the signal pulsed light is always captured by the pump pulsed light.

Further, in Non-Patent Document 1, the central wavelength of the pump pulse light is lengthened by a phenomenon called soliton self-frequency shift. This is caused by the Raman effect occurring in the pump pulsed light and the energy transition from the short wavelength component to the long wavelength component in the pump pulsed light itself. Along with this, the signal pulsed light also has a longer wavelength while being continuously captured by the pump pulsed light. Further, due to the Raman effect, energy is transferred from the pump pulse light to the signal pulse light, and as a result, the pump pulse light intensity decreases and the signal pulse light intensity increases.

When the technique described in Non-Patent Document 1 is used for a tunable wavelength light source, the output wavelength can be controlled by the following method.

The first is to change the energy of the input pump pulse light.
By changing the energy of the pump pulse light, the amount of energy shift from the short wavelength component to the long wavelength component due to the Raman effect generated in a constant optical waveguide changes, and as a result, the output wavelength changes.

Another example is to change the length of the optical waveguide.
The soliton self-frequency shift due to the Raman effect increases as the optical waveguide length increases. Therefore, the shift amount changes according to the length of the optical waveguide, and as a result, the output wavelength changes.

Another example is to change the wavelengths of the input pump pulse light and the signal pulse light.
The amount of frequency shift due to the Raman effect does not differ greatly in an optical waveguide of a certain length, but slightly differs depending on the wavelength. Therefore, the output wavelength also changes according to the input wavelength.

したがって、ポンプパルス光のパルスエネルギー及び時間幅は限定されている。 However, in Non-Patent Document 1 using pump pulse light which is soliton pulse light, the power of pump pulse light is limited as described above. Specifically, when a pulse trapping technique using soliton propagation as in Non-Patent Document 1 is used, the incident pulsed light must be in the anomalous dispersion region of the optical waveguide, and the soliton order N is 0.5. <N <1.5 had to be. The pulse energy and _{E p,} the pulse shape and Sech2 type, the peak intensity _{P 0} is approximately the _E p _{/ T FWHM.} Substituting P ₀ = E _p / T _FWHM into the formula (15) and considering the condition of 0.5 <N <1.5, the E _p · T _FWHM is expressed by the following formula (16-1). The range is obtained.

Therefore, the pulse energy and time width of the pump pulse light are limited.

In the present invention, it is preferable that the pump pulse light is not limited in pulse energy and time width as described above, and specifically, it is preferable that the pump pulse light satisfies the following mathematical formula (16-2). ..

However, in the above formula (16-2), γ is the non-linear coefficient of the non-linear optical waveguide, _TFWHM is the pulse time width of the pump pulse light, E _p is the pulse energy of the pump pulse light, and β ₂ is the secondary of the non-linear optical waveguide. Is the dispersion of.

On the other hand, in an optical parametric wavelength conversion technique as described in Non-Patent Document 2, for example, pump pulse light and signal pulse light (or idler pulse light) are simultaneously incident on a nonlinear fiber. At that time, the energy shifts from the pump pulse light to the signal pulse light (or idler pulse light) due to the optical parametric effect, and the signal pulse light (or idler pulse light) is amplified and output. In Non-Patent Document 2, the output wavelength is controlled by changing the center wavelength and the resonator length of the pump pulse light or the signal pulse light (or idler pulse light). In the optical parametric wavelength conversion technique represented by Non-Patent Document 2, in order to increase the output light intensity in the optical parametric amplification, the intensity of the pump pulse light has been increased so far. Further, in order to maintain the spectral shape of the signal pulsed light (or idler pulsed light), it was necessary to suppress XPM.

As described above, in the optical parametric wavelength conversion technique, since XPM is suppressed, it becomes difficult to generate pulse trapping as described above. Further, in order to suppress XPM, the time width of the pump pulse light must be increased. Further, in order to satisfy the phase matching condition, an optical waveguide in which the wavelength of the pump pulse light is near the zero dispersion wavelength is used, and | β ₂ | is very small. That is, in the wavelength conversion using the parametric gain, it is necessary to input the pump pulse light such that the soliton order N greatly exceeds 1.5 in order to increase the output. Therefore, it is difficult to combine high-output parametric gain with pulse trapping as in Non-Patent Document 1.

Hereinafter, embodiments of the present invention will be described. In the description of the embodiment, the same components will be appropriately designated with the same reference numerals, and the description will be omitted or simplified.

[First Embodiment]
The light source device according to the first embodiment of the present invention will be described with reference to FIGS. 2 to 4. FIG. 2 is a diagram illustrating a light source device according to the first embodiment. FIG. 3 is a graph showing an effective refractive index curve of the nonlinear optical waveguide used in the light source device according to the first embodiment. FIG. 4 is a graph showing the center wavelength of the parametric gain spectrum with respect to the pump pulse light wavelength in the light source device according to the first embodiment.

The light source device according to the first embodiment constitutes OPA. As shown in FIG. 2, the light source device according to the first embodiment includes a pump pulse light source 201 that outputs pump pulse light and a signal pulse light source 209 that outputs signal pulse light. Further, the light source device according to the first embodiment has an optical combiner 207 having two input ports as input ends and one output port as output ends, and a nonlinear optical waveguide 208.

The pump pulse light source 201 is optically connected to one input port of the optical combiner 207 so that the output pump pulse light is input to the optical combiner 207. Further, the signal pulse light source 209 is optically connected to the other input port of the optical combiner 207 so that the output signal pulse light is input to the optical combiner 207. Further, one end of the nonlinear optical waveguide 208 is optically input to the output port of the optical combiner 207 so that the pump pulse light and the signal pulse light combined by the optical combiner 207 are input to the nonlinear optical waveguide 208. It is connected. The other end of the nonlinear optical waveguide 208 is an output end from which light that becomes the output light of the light source device is output.

The pump pulse light source 201 is a wavelength-variable light source, and outputs pump pulse light 210 having a center wavelength of 1020 nm to 1080 nm, an average power of 5 W, a repeating light frequency of 40 MHz, and a pulse time width of 1 ps. The pump pulse light source 201 includes a mode-lock fiber laser 202 using an optical fiber doped with ytterbium (Yb), an optical fiber amplifier 203, a highly nonlinear optical fiber 204, a wavelength filter 205, and an optical fiber amplifier 206.

The output end of the mode lock fiber laser 202 is optically connected to the input end of the optical fiber amplifier 203. The output end of the optical fiber amplifier 203 is optically connected to one end of the highly nonlinear optical fiber 204. The other end of the highly nonlinear optical fiber 204 is connected to the input end of the optical fiber amplifier 206 via a wavelength filter 205. The output end of the optical fiber amplifier 206 is an output end to which the pump pulse light, which is the output light of the pump pulse light source 201, is output.

In the pump pulse light source 201, the light output from the mode lock fiber laser 202 is amplified by the optical fiber amplifier 203 to increase the output. The light whose output is increased by the optical fiber amplifier 203 is widened by the highly nonlinear optical fiber 204. Then, by cutting out by the wavelength filter 205, light in a predetermined wavelength range is cut out from the light band widened by the highly nonlinear optical fiber 204. The light cut out by the wavelength filter 205 is amplified by the optical fiber amplifier 206 to increase the output, and then is output as the pump pulse light 210. The pump pulse light source 201 is configured as a tunable light source capable of changing the wavelength of the pump pulse light 210.

However, the pump pulse light source 201 is not limited to the above configuration. The pump pulse light source 201 may be one that amplifies and outputs light generated from another fiber laser. Alternatively, the output of the laser diode (LD) may be modulated to output pulsed light, or a mode lock laser other than a fiber laser may be used. Further, the optical fiber amplifier 206 may be provided immediately before the nonlinear optical waveguide 208 between the optical combiner 207 and the nonlinear optical waveguide 208. As a result, the waveform distortion of the pump pulse light due to the nonlinear optical effect in the optical waveguide between the optical fiber amplifier 206 and the nonlinear optical waveguide 208 can be suppressed.

The signal pulse light source 209 outputs a signal pulse light 211 of 665 nm to 775 nm. The configuration of the signal pulse light source 209 is not particularly limited, but for example, as will be described later, a signal pulse light 211 of 665 nm to 775 nm is generated.

The optical combiner 207 functions as an optical combiner and has a first input port into which the pump pulse light 210 is input and a second input port in which the signal pulse light 211 is input. Further, the optical combiner 207 has an output port. The optical combiner 207 combines the pump pulse light input to the first input port and the signal pulse light input to the second input port and outputs them from the output port, and the combined pump pulse light and the combined pump pulse light and It is configured to input signal pulsed light to the nonlinear optical waveguide 208. As the optical combiner 207, for example, a polarized beam combiner is used. The optical combiner 207 is not limited to the polarization beam combiner, and may be a fiber coupler or a wavelength division multiplexing coupler (WDM (Wavelength Division Multiplexing) coupler). Alternatively, a spatial optical system using a polarization beam splitter or a dichroic mirror may be used.

The nonlinear optical waveguide 208 is an optical waveguide that produces optical parametric amplification, and specifically, a polarization-holding photonic crystal fiber (LMA-PM-5, NKT Photonics) having a polarization-holding characteristic is used. In the nonlinear optical waveguide 208, energy is transferred from the pump pulsed light to the signal pulsed light by the optical parametric effect.

Thus, in the first embodiment, a polarization-maintaining photonic crystal fiber (LMA-PM-5, NKT Photonics) was used as the nonlinear optical waveguide 208 that produces parametric amplification. The dispersion characteristics of the optical waveguide can be known from the data sheet. However, it is difficult to know about lower-order variances than second-order variances. In the present invention, the 0th-order variance and the 1st-order variance were estimated by the following methods. In addition, the dispersion characteristics along each axis can also be known by actually measuring.

First, the first-order dispersion characteristic can be approximated by the following mathematical formula (17) using the polynomial approximation of Celmeia.

Here, λ is a wavelength and the unit is μm. A, B, C, and D are constants, respectively. When the above formula (17) is differentiated once, the quadratic variance becomes the following formula (18).

Here, c is the speed of light in vacuum. Further, by integrating the mathematical formula (17), the following mathematical formula (19) is obtained. F in equation (19) is a constant.

Further, the dispersion characteristics _Dis and β ₂ have a relationship shown by the following mathematical formula (20).

From the dispersion characteristic D _IS read from the data sheet using equation (20) obtains the beta ₂ data, by fitting the least squares method, were determined A, B, D, and E.

Next, the refractive index depending on the material of the optical fiber was obtained by using the following mathematical formula (21), which is an approximate polynomial of Sermia for the refractive index.

It is considered that the light propagating in the core portion of the optical fiber propagates while partially exuding into the clad portion, as seen in the evanescent wave. Since the optical waveguide used is a photonic crystal fiber, the clad portion is air. The refractive index of the glass used for the optical fiber is about 1.45, and the air is 1. Generally, the effective refractive index of the photonic crystal fiber is reduced by about 1% with respect to the refractive index of the core. Therefore, the effective refractive index was obtained for certain wavelengths λ ₁ and λ ₂ by using the refractive index obtained by subtracting 1% from the refractive index calculated using the mathematical formula (21) as the effective refractive index. Since the relationship between the refractive index and the dispersion is expressed by the mathematical formula (1), the mathematical formulas C and F are obtained for certain wavelengths λ ₁ and λ ₂ , and C and F are obtained by solving the simultaneous equations. In this way, the effective refractive index curve was obtained for the Fast axis.

Regarding the Slow axis, the data sheet shows the value of Birefringence (Δn) indicating the difference in refractive index between the Fast axis and the Slow axis, and it was obtained by adding Δn to the effective refractive index curve obtained by the above method. ..

FIG. 3 shows the effective refractive index curves obtained for each of the Fast axis and the Slow axis of the polarization-maintaining photonic crystal fiber.

In the light source device according to the first embodiment, it is possible to increase the optical output by performing optical parametric amplification expanded to a short wavelength as follows.

The pump pulse light 210 output from the pump pulse light source 101 is input to the first input port of the optical combiner 207, which is the first polarization beam combiner. Further, the pump pulse light 210 input to the optical combiner 207 is output from the output port of the optical combiner 207 and propagates along the Slow axis of the nonlinear optical waveguide 208, which is a polarization-maintaining photonic crystal fiber. It is input to one end of the waveguide 208.

In this way, the pump pulse light source 101 inputs the pump pulse light 210 to the nonlinear optical waveguide 208 with the center wavelength changed from 1020 nm to 1080 nm.

As shown in FIG. 4, when the pump pulse light 210 and the signal pulse light 211 propagate on the same axis, a parametric gain spectrum having a center wavelength of about 680 nm to 820 nm is obtained. On the other hand, when the pump pulse light 210 propagates on the Slow axis and the signal pulse light 211 propagates on the Fast axis and both pulsed lights propagate at right angles as in the present embodiment, the center wavelength is about 665 nm to 775 nm. It is possible to obtain a parametric gain spectrum. That is, the parametric gain wavelength band can be extended to the short wavelength side.

Therefore, in the present embodiment, the signal pulse light 211 having a center wavelength of 665 nm to 775 nm is input to the other second input port of the optical combiner 207, which is a polarization beam combiner, in synchronization with the pump pulse light 210. The signal pulse light 211 is output from the signal pulse light source 209.

The signal pulsed light 211 was generated by: A pulsed light of 1550 nm, which is an Er fiber laser output, was incident on an optical waveguide having high non-linearity to widen the band so as to cover 1300 nm to 1550 nm. Then, the wavelength was converted by periodic polarization inversion lithium niobate (PPLN). Further, a wavelength filter was used to obtain signal pulsed light having a center wavelength of 665 nm to 775 nm. However, the signal pulsed light is not limited to this form, and may be a semiconductor laser output or a Ti: Sapphire laser output.

The signal pulsed light 211 input to the optical combiner 207 is combined with the pump pulsed light 210 and output from the output port of the optical combiner 207, and propagates along the Fast axis of the nonlinear optical waveguide 208. Is entered at one end of.

In this way, according to the present embodiment, it is possible to perform optical parametric amplification expanded to the short wavelength side. From the other end of the nonlinear optical waveguide 208, the light generated by the parametric gain due to the optical parametric amplification expanded to the short wavelength side is output as output light.

A second polarization beam combiner is used as a polarization beam splitter at the other end of the nonlinear optical waveguide 208, which is the output end of the light source device, in addition to the first polarization beam combiner used as the optical combiner 207. May be connected for. The second polarized beam combiner separates the remaining pump pulsed light, which remains unconverted by the optical parametric effect, from the light generated by the parametric gain. As a result, it is possible to reduce or eliminate the influence of XPM generated in other than the nonlinear optical waveguide 208, and it is possible to suppress the distortion of light generated by the parametric gain.

Further, the first and second polarization beam combiners may be fiber couplers or WDM couplers. Alternatively, a spatial optical system using a polarization beam splitter or a dichroic mirror may be used. This makes it possible to reduce the wavelength-dependent characteristics of the polarization beam combiner.

[Second Embodiment]
The light source device according to the second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a diagram illustrating a light source device according to the second embodiment.

The light source device according to the second embodiment constitutes an OPO. In the light source device according to the second embodiment, the pump pulse light source 201, the optical combiner 207 which is the first polarization beam combiner, and the nonlinear optical waveguide 208 are the same as those used in the first embodiment.

The other end, which is the output end of the nonlinear optical waveguide 208, is optically connected to the optical separator 401, which is a second polarization beam combiner. The second polarization beam combiner is connected in the opposite direction to the first polarization beam combiner, thereby acting as a polarization beam splitter. The optical separator 401 functions as an optical separator and separates the remaining pump pulsed light 406, which remains without converting energy by the optical parametric effect, from the light generated by the parametric gain. The light generated by the parametric gain is output from the first output port of the optical separator 401. The remaining pump pulsed light 406 is output from the second output port of the optical separator 401.

An optical fiber coupler 402 is optically connected to the first output port of the optical separator 401. Part of the light generated by the parametric gain is taken out as output light 405 by the light take-out device 402 that functions as a light take-out unit. The output light 405 is output from the first output port of the optical take-out device 402. The remaining portion of the light generated by the parametric gain is output from the second output port of the optical extractor 402 and is the second input of the optical combiner 207, which is the first polarized beam combiner as the signal pulsed light 403. Input to the port. The second output port of the optical ejector 402 is optically connected to the second input port of the optical combiner 207.

An optical delayer 404 is inserted between the optical ejector 402 and the optical combiner 207. The optical delayer 404 can delay the signal pulsed light input to the input port of the optical combiner 207, and can adjust the delay time of the signal pulsed light. By controlling the optical delayer 404, the repeatedly input pump pulsed light 210 and the signal pulsed light 403 generated by the parametric gain are overlapped in synchronization with the timing. The pump pulse light 210 and the signal pulse light 403 that are overlapped at the same timing are combined by the optical combiner 207 and input to one end of the nonlinear optical waveguide 208.

When the length of the resonator is adjusted so that the repetition frequency of the pump pulse light output from the pump pulse light source 201 and the resonance frequency of the resonator configured in the present embodiment match, the optical delay It is not necessary to provide the vessel 404. Alternatively, if the repetition frequency of the pump pulse light is adjusted to match the resonance frequency of the resonator configured in the present embodiment, the optical delayer 404 may not be provided. For example, when an optical delayer is provided in the mode lock fiber laser 202 to adjust the optical path length, or when pump pulse light is generated by intensity-modulating CW light, the modulation frequency is adjusted. Can be realized with.

Here, the first polarization beam combiner used as the optical combiner 207 and the second polarization beam combiner used as the optical separator 401 may be an optical fiber coupler or a WDM coupler. Alternatively, a spatial optical system using a polarization beam splitter or a dichroic mirror may be used. This makes it possible to reduce the wavelength-dependent characteristics of the polarization beam combiner.

Further, as in the first embodiment, an optical amplifier such as an optical fiber amplifier may be arranged immediately before the nonlinear optical waveguide 208, and a mechanism for amplifying the pump pulse light may be provided in the resonator. This makes it possible to reduce the nonlinear optical effect that the high-power pump pulse light receives between the pump pulse light source and the nonlinear optical waveguide, and suppress the waveform distortion of the pump pulse light.
According to this embodiment, a resonator is configured, and a tunable output with a high output and a short wavelength can be obtained.

[Third Embodiment]
The light source device according to the third embodiment of the present invention will be described with reference to FIG. FIG. 6 shows the center wavelength of the parametric gain spectrum with respect to the pump pulse light wavelength in the third embodiment and the wavelength at which the pump pulse light wavelength and the group velocity match in the Fast axis orthogonal to the Slow axis of the optical waveguide. It is a graph.

The light source device according to the third embodiment constitutes OPA and has the same configuration as shown in FIG. 2 as in the first embodiment, but the pump pulse light source 201 and the signal pulse light source 209 are described below. It is different from the first embodiment. As the nonlinear optical waveguide 208 that produces optical parametric amplification, a polarization-maintaining photonic crystal fiber (LMA-PM-5, NKT Photonics) is used as in the first embodiment.

In the third embodiment, the pump pulse light source 201 outputs pulsed light having a center wavelength of 1150 nm, an average power of 1 W, a repeating light frequency of 40 MHz, and a pulse time width of 10 ps. In the pump pulse light source 201, the light whose output is increased by a mode-lock fiber laser using an optical fiber doped with ytterbium (Yb) and an optical fiber amplifier is lengthened by a highly nonlinear optical fiber having anomalous dispersion characteristics.

However, the pump pulse light source 201 is not limited to the above configuration. The pump pulse light source 201 may be one that cuts out light having a diameter of 1150 nm from light broadened by a highly nonlinear optical fiber having normal dispersion and outputs the light. Light may be generated from another fiber laser, and the light may be amplified and output. Alternatively, the output of the laser diode (LD) may be modulated to output pulsed light, or a mode lock laser other than a fiber laser may be used.

The pump pulse light output from the pump pulse light source 201 is input to the optical combiner 207, which is a polarization beam combiner, as in the first embodiment. Then, the pump pulse light is input to the nonlinear optical waveguide 208, which is an optical waveguide that produces optical parametric amplification. Here, the pump pulse light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the slow axis of the nonlinear optical waveguide 208.

From the effective refractive index curve obtained in the first embodiment and the characteristics of the input pump pulse light, the center wavelength of the parametric gain that changes with respect to the center wavelength of the pump pulse light was obtained. Further, on the Fast axis orthogonal to the Slow axis of the nonlinear optical waveguide, a wavelength having the same group velocity as the center wavelength of the input pump pulse light was obtained. A plot of them is shown in FIG. By inputting pump pulse light having a center wavelength of 1150 nm to the Slow axis, a parametric gain having a center wavelength of 950 nm can be obtained on the Fast axis, and the group velocities are the same.

In the present embodiment, the signal pulse light source 209 outputs signal pulsed light having a center wavelength of 950 nm. The signal pulsed light having a central wavelength of 950 nm is input to the optical combiner 207 which is a polarization beam combiner. Then, the signal pulsed light is input to the nonlinear optical waveguide 208 that produces a parametric gain. Here, the signal pulsed light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the Fast axis of the nonlinear optical waveguide 208.

The signal pulse light is synchronized with the pump pulse light, is combined with the pump pulse light by the optical combiner 207, and is input to one end of the nonlinear optical waveguide 208. By inputting the signal pulse light in synchronization with the pump pulse light, the signal pulse light is amplified by the parametric gain in the nonlinear optical waveguide 208. Further, in the nonlinear optical waveguide 208, since the group velocity of the pump pulse light and the group velocity of the signal pulse light match, both pulsed lights propagate without walking off and the signal pulsed light is amplified.

On the other hand, from the phase matching condition, the length of the nonlinear optical waveguide 208 in which the energy transitions from the pump pulse light to the signal pulse light can be obtained. When this length is exceeded, energy transitions from signal pulsed light to pump pulsed light. In the present embodiment, the length is about 1 m, and the pump pulsed light and the signal pulsed light can be sufficiently propagated to the nonlinear optical waveguide 208 of this length regardless of the walkoff.

[Fourth Embodiment]
The light source device according to the fourth embodiment of the present invention will be described.
The light source device according to the fourth embodiment constitutes an OPO and has the same configuration as shown in FIG. 5 as the second embodiment. However, in the light source device according to the fourth embodiment, the pump pulse light source 201, the optical combiner 207 which is the first polarization beam combiner, and the nonlinear optical waveguide 208 are the same as those used in the third embodiment.

The other end, which is the output end of the nonlinear optical waveguide 208, is optically connected to the optical separator 401, which is the second polarization beam combiner, as in the second embodiment. The optical separator 401 separates the residual pump pulsed light from the light generated by the parametric gain, as in the second embodiment.

As in the second embodiment, a part of the light generated by the parametric gain is taken out as output light by the optical take-out device 402 which is an optical fiber coupler. The remaining portion of the light generated by the parametric gain is input to the optical combiner 207, which is the first polarization beam combiner, as in the second embodiment.

Similar to the second embodiment, an optical delayer 404 is inserted between the optical ejector 402 and the optical combiner 207, and by controlling the optical delayer 404, a pump pulse that is repeatedly input. The light and the light generated by the parametric gain are superimposed in synchronization at the same timing.
According to this embodiment, a resonator is configured and a high output wavelength conversion output can be obtained.

[Fifth Embodiment]
The light source device according to the fifth embodiment of the present invention will be described with reference to FIG. FIG. 4 is a graph showing the center wavelength of the parametric gain spectrum with respect to the pump pulse light wavelength in the light source device according to the fifth embodiment.

The light source device according to the fifth embodiment constitutes OPA, and has the same configuration as shown in FIG. 2 as the first embodiment. As the nonlinear optical waveguide 208 that produces optical parametric amplification, the same polarization-maintaining photonic crystal fiber (LMA-PM-5, NKT Photonics) as in the first embodiment was used. The pump pulse light source 201 is the same light source as in the first embodiment.

The pump pulse light output from the pump pulse light source 201 is input to one input port of the optical combiner 207 which is a polarization beam combiner. Then, the pump pulse light input to the optical combiner 207 is input to one end of the nonlinear optical waveguide 208 that causes optical parametric amplification. Here, unlike the first embodiment, in the present embodiment, the pump pulse light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the Fast axis of the nonlinear optical waveguide 208.

Here, consider a case where the pump pulse light is input to the nonlinear optical waveguide by changing the center wavelength from 1020 nm to 80,000 nm. In this case, as shown in FIG. 4, when the pump pulse light and the signal pulse light propagate on the same axis, a parametric gain spectrum having a center wavelength of about 680 nm to 820 nm is obtained. On the other hand, when the pump pulse light propagates on the Fast axis, the signal pulse light propagates on the Slow axis, and both pulsed lights propagate at right angles as in the present embodiment, the parametric gain has a center wavelength of about 725 nm to 1000 nm. It is possible to obtain a spectrum. That is, the parametric gain wavelength band can be extended to the long wavelength side.

Therefore, in the present embodiment, the signal pulse light of 725 nm to 1000 nm is input to another input port of the optical combiner 207, which is a polarization beam combiner, in synchronization with the pump pulse light. The signal pulse light is output from the signal pulse light source 209.

The signal pulsed light was generated by: A pulsed light of 1550 nm, which is an Er fiber laser output, was incident on an optical waveguide having high non-linearity to widen the band so as to cover 1450 nm to 2000 nm. Then, the wavelength was converted by PPLN. Further, a wavelength filter was used to obtain signal pulsed light of 725 nm to 1000 nm. However, the signal pulsed light is not limited to this form, and may be a semiconductor laser output or a Ti: Sapphire laser output.

The signal pulsed light 211 input to the optical combiner 207 is combined with the pump pulsed light 210 and output from the output port of the optical combiner 207, and propagates along the Slow axis of the nonlinear optical waveguide 208. Is entered at one end of.

In this way, according to the present embodiment, it is possible to perform optical parametric amplification expanded to the long wavelength side. From the other end of the nonlinear optical waveguide 208, the light generated by the parametric gain due to the optical parametric amplification expanded to the long wavelength side is output as output light.

[Sixth Embodiment]
The light source device according to the sixth embodiment of the present invention will be described.

The light source device according to the sixth embodiment constitutes an OPO and has the same configuration as shown in FIG. 5 as the second embodiment. However, in the light source device according to the sixth embodiment, the pump pulse light source 201, the optical combiner 207 which is the first polarization beam combiner, and the nonlinear optical waveguide 208 are the same as those used in the fifth embodiment.

The other end, which is the output end of the nonlinear optical waveguide 208, is optically connected to the optical separator 401, which is the second polarization beam combiner, as in the second embodiment. The optical separator 401 separates the residual pump pulsed light from the light generated by the parametric gain, as in the second embodiment.

As in the second embodiment, a part of the light generated by the parametric gain is taken out as output light by the optical take-out device 402 which is an optical fiber coupler. The rest of the light generated by the parametric gain is input to the optical combiner 207, which is the first polarization beam combiner, as in the second embodiment.

Similar to the second embodiment, an optical delayer 404 is inserted between the optical ejector 402 and the optical combiner 207, and by controlling the optical delayer 404, a pump pulse that is repeatedly input. The light and the light generated by the parametric gain are superimposed in synchronization at the same timing.
According to this embodiment, a resonator is configured, and a wavelength conversion output having a high output and a variable wavelength at a long wavelength can be obtained.

[7th Embodiment]
The light source device according to the seventh embodiment of the present invention will be described with reference to FIG. FIG. 7 shows that the pump pulse light wavelength and the group velocity match in the center wavelength of the parametric gain spectrum with respect to the pump pulse light wavelength and the Fast axis orthogonal to the Slow axis of the optical waveguide in the light source device according to the seventh embodiment. It is a graph which shows the wavelength.

The light source device according to the seventh embodiment constitutes OPA and has the same configuration as shown in FIG. 2 as in the first embodiment, but the pump pulse light source 201 and the signal pulse light source 209 are described below. It is different from the first embodiment. As the nonlinear optical waveguide 208 that produces optical parametric amplification, a polarization-maintaining photonic crystal fiber (LMA-PM-5, NKT Photonics) is used as in the first embodiment.

In the seventh embodiment, the pump pulse light source 201 outputs pulsed light having a center wavelength of 1150 nm to 1300 nm, an average power of 5.1 W, a repeating light frequency of 40 MHz, and a pulse time width of 1 ps. In the pump pulse light source 201, pulsed light whose output is increased by a mode-lock fiber laser using an optical fiber doped with ytterbium (Yb) and an optical fiber amplifier is input to a highly nonlinear optical fiber having anomalous dispersion characteristics. A soliton self-frequency shift occurs in a highly nonlinear optical fiber having anomalous dispersion characteristics, and pulsed light shifted to the long wavelength side is obtained. By modulating the intensity of the input pulsed light, the output wavelength is controlled, and a tunable pump pulsed light can be obtained.

However, the pump pulse light source is not limited to the above configuration, and light of 1150 nm to 1300 nm may be cut out from the light widened by a highly nonlinear optical fiber having a normal dispersion. It may be generated from another fiber laser and amplified. Alternatively, the output of the laser diode (LD) may be modulated and pulsed, or a mode lock laser other than a fiber laser may be used.

The pump pulse light output from the pump pulse light source 201 is input to one input port of the optical combiner 207 which is a polarization beam combiner. Then, the pump pulse light is input to the nonlinear optical waveguide 208, which is an optical waveguide that produces optical parametric amplification. Here, the pump pulse light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the Fast axis of the nonlinear optical waveguide 208.

From the effective refractive index curve obtained in the first embodiment and the characteristics of the input pump pulse light, the center wavelength of the parametric gain that changes with respect to the center wavelength of the pump pulse light was obtained. Further, on the Slow axis orthogonal to the Fast axis of the nonlinear optical waveguide, a wavelength having the same group velocity as the center wavelength of the input pump pulse light was obtained. A plot of them is shown in FIG. By inputting pump pulse light having a center wavelength of 1150 nm to 1300 nm to the Fast axis, a parametric gain having a center wavelength of 1100 nm to 1280 nm can be obtained on the Slow axis, and the group velocities are the same.

In the present embodiment, the signal pulse light source 209 outputs signal pulsed light having a center wavelength of 1100 nm to 1280 nm. The signal pulsed light having a center wavelength of 1100 nm to 1280 nm is input to another input port of the optical combiner 207 which is a polarization beam combiner. Then, the signal pulsed light is input to the nonlinear optical waveguide 208 that produces a parametric gain. Here, the signal pulsed light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the slow axis of the nonlinear optical waveguide 208. That is, in the present embodiment, unlike the first embodiment, the input port of the optical combiner 207, which is a polarization beam combiner, is replaced with the pump pulse light and the signal pulse light.

The signal pulse light is synchronized with the pump pulse light, is combined with the pump pulse light by the optical combiner 207, and is input to one end of the nonlinear optical waveguide 208. By inputting the signal pulse light in synchronization with the pump pulse light, the signal pulse light is amplified by the parametric gain in the nonlinear optical waveguide 208. Further, in the nonlinear optical waveguide 208, since the group velocity of the pump pulse light and the group velocity of the signal pulse light match, both pulsed lights propagate without walking off and the signal pulsed light is amplified.

On the other hand, from the phase matching condition, the length of the nonlinear optical waveguide 208 in which the energy transitions from the pump pulse light to the signal pulse light can be obtained. When this length is exceeded, energy transitions from signal pulsed light to pump pulsed light. In the present embodiment, the length is about 1 m, and the pump pulsed light and the signal pulsed light can be sufficiently propagated to the nonlinear optical waveguide 208 of this length regardless of the walkoff.

[8th Embodiment]
The light source device according to the eighth embodiment of the present invention will be described.

The light source device according to the eighth embodiment constitutes an OPO and has the same configuration as shown in FIG. 5 as the second embodiment. However, in the light source device according to the eighth embodiment, the pump pulse light source 201, the optical combiner 207 which is the first polarization beam combiner, and the nonlinear optical waveguide 208 are the same as those of the seventh embodiment.

The other end, which is the output end of the nonlinear optical waveguide, is optically connected to the optical separator 401, which is the second polarization beam combiner, as in the second embodiment. The optical separator 401 separates the residual pump pulsed light from the light generated by the parametric gain, as in the second embodiment.

As in the second embodiment, a part of the light generated by the parametric gain is taken out as output light by the optical take-out device 402 which is an optical fiber coupler. The remaining portion of the light generated by the parametric gain is input to the optical combiner 207, which is the first polarization beam combiner, as in the second embodiment.

Similar to the second embodiment, an optical delayer 404 is inserted between the optical ejector 402 and the optical combiner 207, and by controlling the optical delayer 404, a pump pulse that is repeatedly input. The light and the light generated by the parametric gain are superimposed in synchronization at the same timing.
According to this embodiment, a resonator is configured, and a high output and wavelength tunable wavelength conversion output can be obtained.

[9th Embodiment]
The light source device according to the ninth embodiment of the present invention will be described with reference to FIGS. 8 and 9. FIG. 8 is a graph showing an effective refractive index curve of the nonlinear optical waveguide used in the light source device according to the ninth embodiment. FIG. 9 is a graph showing the center wavelength of the parametric gain spectrum with respect to the pump pulse light wavelength in the light source device according to the ninth embodiment.

The light source device according to the ninth embodiment constitutes OPA and has the same configuration as shown in FIG. 2 as in the first embodiment, but has a pump pulse light source 201, a signal pulse light source 209, and a nonlinear optical waveguide 208. Is different from the first embodiment as described below.

In the ninth embodiment, the pump pulse light source 201 outputs pump pulse light having a central wavelength of 1020 nm to 1080 nm, an average power of 10 W, a repeating light frequency of 40 MHz, and a pulse time width of 0.8 ps. In the pump pulse light source 201, the light high output by the mode-lock fiber laser using the ytterbium (Yb) -doped optical fiber and the optical fiber amplifier is widened by the high nonlinear optical fiber. A tunable output is obtained by cutting out light in a predetermined wavelength range from the widebanded light with a wavelength filter and changing the center wavelength of the cut-out spectrum. Then, the output is amplified by an optical fiber amplifier using a Yb-doped optical fiber. In this way, the pump pulsed light having the output characteristics as described above is obtained.

However, the pump pulse light source 201 is not limited to the above configuration. The pump pulse light source 201 may generate light of 1060 nm from another fiber laser, amplify the light, and output the light. Alternatively, the output of the laser diode (LD) may be modulated to output pulsed light, or a mode lock laser other than a fiber laser may be used. Alternatively, a tunable laser in which a tunable filter is provided in a resonator of a mode lock laser using a Yb-doped optical fiber may be used.

The pump pulse light output from the pump pulse light source 201 is input to one input port of the optical combiner 207 which is a polarization beam combiner. Then, the pump pulse light is input to the nonlinear optical waveguide 208, which is an optical waveguide that produces optical parametric amplification. Here, the pump pulse light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the slow axis of the nonlinear optical waveguide 208.

In the present embodiment, as a nonlinear optical waveguide 208 that produces optical parametric amplification, a polarization-maintaining photonic crystal fiber having polarization-holding characteristics (PM-PCF, Katsuhiro Takenaga, 4 outsiders, "Broadband polarization-holding photonic crystal fiber" , Fujikura Giho, Fujikura Co., Ltd., April 2005, No. 108, p.6-9). The effective refractive index of the optical waveguide is shown in FIG. The dispersion β on different birefringence axes can be obtained based on the curve of the effective refractive index.

From the effective refractive index curve and the characteristics of the input pump pulse light, the center wavelength of the parametric gain spectrum that changes with respect to the center wavelength of the pump pulse light was obtained.

The pump pulsed light was input to the nonlinear optical waveguide 208 with the center wavelength changed from 1020 nm to 1080 nm. As shown in FIG. 9, when the pump pulse light and the signal pulse light propagate on the same Slow axis, a parametric gain spectrum having a center wavelength of about 700 nm to 790 nm is obtained. On the other hand, when the pump pulsed light propagates on the Slow axis and the signal pulsed light propagates on the Fast axis and both pulsed lights propagate at right angles as in the present embodiment, a parametric gain spectrum of about 695 nm to 760 nm is obtained. It becomes possible. That is, the parametric gain wavelength band can be extended to the short wavelength side.

Therefore, in the present embodiment, the signal pulse light having a center wavelength of 695 nm to 760 nm is input to another input port of the optical combiner 207, which is a polarization beam combiner, in synchronization with the pump pulse light. The signal pulse light is output from the signal pulse light source 209.

The signal pulsed light was generated by: A pulsed light having a center wavelength of 1550 nm, which is an Er fiber laser output, was incident on an optical waveguide having high non-linearity to widen the band so as to cover 1390 nm to 1520 nm. Then, the wavelength was converted by PPLN. Further, a wavelength filter was used to obtain signal pulsed light having a center wavelength of 695 nm to 760 nm. However, the signal pulsed light is not limited to this form, and may be a semiconductor laser output or a Ti: Sapphire laser output.

The signal pulsed light input to the optical combiner 207 is combined with the pump pulsed light 210, output from the output port of the optical combiner 207, and propagates along the Fast axis of the nonlinear optical waveguide 208. It is input at one end.

In this way, according to the present embodiment, it is possible to perform optical parametric amplification expanded to the short wavelength side. From the other end of the nonlinear optical waveguide 208, the light generated by the parametric gain due to the optical parametric amplification expanded to the short wavelength side is output as output light.

[10th Embodiment]
The light source device according to the tenth embodiment of the present invention will be described.
The light source device according to the tenth embodiment constitutes an OPO and has the same configuration as shown in FIG. 5 as the second embodiment. However, in the light source device according to the tenth embodiment, the pump pulse light source 201, the optical combiner 207 which is the first polarization beam combiner, and the nonlinear optical waveguide 208 are the same as those of the ninth embodiment.

The other end, which is the output end of the nonlinear optical waveguide 208, is optically connected to the optical separator 401, which is the second polarization beam combiner, as in the second embodiment. The optical separator 401 separates the residual pump pulsed light from the light generated by the parametric gain, as in the second embodiment.

As in the second embodiment, a part of the light generated by the parametric gain is taken out as output light by the optical take-out device 402 which is an optical fiber coupler. The remaining portion of the light generated by the parametric gain is input to the optical combiner 207, which is the first polarization beam combiner, as in the second embodiment.

Similar to the second embodiment, an optical delayer 404 is inserted between the optical ejector 402 and the optical combiner 207, and by controlling the optical delayer 404, a pump pulse that is repeatedly input. The light and the light generated by the parametric gain are superimposed in synchronization at the same timing.
According to this embodiment, a resonator is configured, and a tunable output with a high output and a short wavelength can be obtained.

[11th Embodiment]
The light source device according to the eleventh embodiment of the present invention will be described with reference to FIG. FIG. 10 shows that the pump pulse light wavelength and the group velocity match in the center wavelength of the parametric gain spectrum with respect to the pump pulse light wavelength and the Fast axis orthogonal to the Slow axis of the optical waveguide in the light source device according to the eleventh embodiment. It is a graph which shows the wavelength.

The light source device according to the eleventh embodiment constitutes OPA and has the same configuration as shown in FIG. 2 as in the first embodiment, but the pump pulse light source 201 and the signal pulse light source 209 are described below. It is different from the first embodiment. As the optical waveguide that produces optical parametric amplification, the same polarization-maintaining photonic crystal fiber (PM-PCF) as in the ninth embodiment is used.

In the eleventh embodiment, the pump pulse light source 201 outputs pulsed light having a center wavelength of 1060 nm, an average power of 1 W, a repeating light frequency of 40 MHz, and a pulse time width of 10 ps. In the pump pulse light source 201, the light high output by the mode-lock fiber laser using the ytterbium (Yb) -doped optical fiber and the optical fiber amplifier is widened by the high nonlinear optical fiber. Light in a predetermined wavelength range was cut out from the widebanded light by a wavelength filter, and the center wavelength of the cut out spectrum was set to 1060 nm. Then, it is amplified by an optical fiber amplifier using an optical fiber doped with Yb. In this way, the pump pulsed light having the output characteristics as described above is obtained.

However, the pump pulse light source 201 is not limited to the above configuration. The pump pulse light source 201 may generate light of 1060 nm from another fiber laser, amplify the light, and output the light. Alternatively, the output of the laser diode (LD) may be modulated to output pulsed light, or a mode lock laser other than a fiber laser may be used. Alternatively, a tunable laser in which a tunable filter is provided in a resonator of a mode lock laser using a Yb-doped optical fiber may be used.

The pump pulse light output from the pump pulse light source 201 is input to one input port of the optical combiner 207 which is a polarization beam combiner. Then, the pump pulse light is input to the nonlinear optical waveguide 208, which is an optical waveguide that produces optical parametric amplification. Here, the pump pulse light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the slow axis of the nonlinear optical waveguide 208.

From the effective refractive index curve obtained in the ninth embodiment and the characteristics of the input pump pulse light, the center wavelength of the parametric gain that changes with respect to the center wavelength of the pump pulse light was obtained. Further, on the Fast axis orthogonal to the Slow axis of the nonlinear optical waveguide, a wavelength having the same group velocity as the center wavelength of the input pump pulse light was obtained. A plot of them is shown in FIG. By inputting the pump pulse light having a center wavelength of 1060 nm to the Slow axis, a parametric gain having a center wavelength of 800 nm can be obtained on the Fast axis, and the group velocities are the same.

Therefore, in the present embodiment, the signal pulse light source 209 outputs a signal pulse light having a center wavelength of 800 nm. The signal pulsed light having a central wavelength of 800 nm is input to another input port of the optical combiner 207, which is a polarization beam combiner. Then, the signal pulsed light is input to the nonlinear optical waveguide 208 that produces a parametric gain. Here, the signal pulsed light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the Fast axis of the nonlinear optical waveguide 208.

The signal pulse light is synchronized with the pump pulse light, is combined with the pump pulse light by the optical combiner 207, and is input to one end of the nonlinear optical waveguide 208. By inputting the signal pulse light in synchronization with the pump pulse light, the signal pulse light is amplified by the parametric gain in the nonlinear optical waveguide 208. Further, in the non-linear optical waveguide 208, since the group velocity of the pump pulse light and the group velocity of the signal pulsed light match, both pulsed lights propagate without walking off and the signal pulsed light is amplified.

As the signal pulsed light having a center wavelength of 800 nm, the pulsed light having a center wavelength of 1550 nm, which is an Er fiber laser output, was wavelength-shifted to 1600 nm, and the wavelength was converted to 800 nm by PPLN. However, the light having a center wavelength of 800 nm is not limited to this form, and may be a semiconductor laser output or a Ti: Sapphire laser output.

When the pump pulse light and the signal pulse light have the same polarization axis, there is a group velocity difference of about 1 ps / m between 1060 nm and 800 nm. Therefore, in this case, in the vicinity of the peak of the pulse width of 10 ps (1/10 of the full width at half maximum of the time), the walk-off occurs at about 1 m. However, according to this embodiment, it is possible to propagate 1 m or more, and it is possible to greatly amplify the signal pulsed light having a center wavelength of 800 nm.

[Twelfth Embodiment]
The light source device according to the twelfth embodiment of the present invention will be described.
The light source device according to the twelfth embodiment constitutes an OPO and has the same configuration as shown in FIG. 5 as the second embodiment. However, in the light source device according to the twelfth embodiment, the pump pulse light source 201, the optical combiner 207 which is the first polarization beam combiner, and the nonlinear optical waveguide 208 are the same as those of the eleventh embodiment.

The other end, which is the output end of the nonlinear optical waveguide 208, is optically connected to the optical separator 401, which is the second polarization beam combiner, as in the second embodiment. The optical separator 401 separates the residual pump pulsed light from the light generated by the parametric gain, as in the second embodiment.

As in the second embodiment, a part of the light generated by the parametric gain is taken out as output light by the optical take-out device 402 which is an optical fiber coupler. The remaining portion of the light generated by the parametric gain is input to the optical combiner 207, which is the first polarization beam combiner, as in the second embodiment.

Similar to the second embodiment, an optical delayer 404 is inserted between the optical ejector 402 and the optical combiner 207, and by controlling the optical delayer 404, a pump pulse that is repeatedly input. The light and the light generated by the parametric gain are superimposed in synchronization at the same timing.
According to this embodiment, a resonator is configured, and a high output wavelength conversion output of 800 nm can be obtained.

[13th Embodiment]
The light source device according to the thirteenth embodiment of the present invention will be described with reference to FIG. FIG. 9 is a graph showing the center wavelength of the parametric gain spectrum with respect to the pump pulse light wavelength in the light source device according to the thirteenth embodiment.

The light source device according to the thirteenth embodiment constitutes OPA and has the same configuration as shown in FIG. 2 as the first embodiment. However, as the pump pulse light source 201, a light source similar to the light source used in the ninth embodiment was used.
Further, as the nonlinear optical waveguide 208 that produces optical parametric amplification, an optical fiber similar to the optical fiber used in the ninth embodiment was used.

The pump pulse light output from the pump pulse light source 201 is input to one input port of the optical combiner 207 which is a polarization beam combiner. Then, the pump pulse light input to the optical combiner 207 is input to one end of the nonlinear optical waveguide 208 that causes optical parametric amplification. Here, unlike the first embodiment, in the present embodiment, the pump pulse light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the Fast axis of the nonlinear optical waveguide 208.

The pump pulsed light was input to the nonlinear optical waveguide by changing the center wavelength from 1020 nm to 1080 nm. As shown in FIG. 9, when the pump pulse light and the signal pulse light propagate on the same Slow axis, a parametric gain spectrum having a center wavelength of about 700 nm to 790 nm is obtained. On the other hand, when the pump pulse light propagates on the Fast axis, the signal pulse light propagates on the Slow axis, and both pulsed lights propagate at right angles as in the present embodiment, the parametric gain has a center wavelength of about 850 nm to 960 nm. It is possible to obtain a spectrum. That is, the parametric gain wavelength band can be extended to the long wavelength side.

Therefore, in the present embodiment, the signal pulse light having a center wavelength of 850 nm to 960 nm is input to another input port of the optical combiner 207, which is a polarization beam combiner, in synchronization with the pump pulse light. The signal pulse light is output from the signal pulse light source 209.

The signal pulsed light was generated by: A soliton self-frequency light source was used, in which a pulsed light having a center wavelength of 1550 nm, which is an Er fiber laser output, was incident on an optical waveguide having anomalous dispersion characteristics and high non-linearity to shift the wavelength so as to cover 1700 nm to 1920 nm. The wavelength was controlled by the intensity of the pulsed light having an input center wavelength of 1550 nm. Then, the wavelength was converted to a central wavelength of 850 nm to 960 nm by PPLN. However, the signal pulsed light is not limited to this form, and may be a semiconductor laser output or a Ti: Sapphire laser output.
According to this embodiment, it is possible to perform parametric amplification expanded to the long wavelength side.

[14th Embodiment]
The light source device according to the 14th embodiment of the present invention will be described.
The light source device according to the fourteenth embodiment constitutes an OPO and has the same configuration as shown in FIG. 5 as the second embodiment. However, in the light source device according to the 14th embodiment, the pump pulse light source 201, the optical combiner 207 which is the first polarization beam combiner, and the nonlinear optical waveguide 208 are the same as those in the 13th embodiment.

The other end, which is the output end of the nonlinear optical waveguide 208, is optically connected to the optical separator 401, which is the second polarization beam combiner, as in the second embodiment. The optical separator 401 separates the residual pump pulsed light from the light generated by the parametric gain, as in the second embodiment.

Part of the light generated by the parametric gain is taken out as output light by the optical take-out device 402 which is an optical fiber coupler. The remaining portion of the light generated by the parametric gain is input to the optical combiner 207, which is the first polarization beam combiner.

Similar to the second embodiment, an optical delayer 404 is inserted between the optical ejector 402 and the optical combiner 207, and by controlling the optical delayer 404, a pump pulse that is repeatedly input. The light and the light generated by the parametric gain are superimposed in synchronization at the same timing.
According to this embodiment, a resonator is configured, and a tunable output with a high output and a short wavelength can be obtained.

[Fifteenth Embodiment]
The light source device according to the fifteenth embodiment of the present invention will be described.
The light source device according to the fifteenth embodiment constitutes OPA and has the same configuration as shown in FIG. 2 as the first embodiment. However, as the pump pulse light source 201, a light source similar to the light source used in the ninth embodiment was used. Here, the center wavelength of the pump pulse light was fixed at 1035 nm. Further, as the nonlinear optical waveguide 208 that produces optical parametric amplification, an optical fiber similar to the optical fiber used in the ninth embodiment was used.

The pump pulse light output from the pump pulse light source 201 is input to one input port of the optical combiner 207 which is a polarization beam combiner. Then, the pump pulse light input to the optical combiner 207 is input to one end of the nonlinear optical waveguide 208 that causes optical parametric amplification. Here, unlike the first embodiment, in the present embodiment, the pump pulse light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the Fast axis of the nonlinear optical waveguide 208.

From the effective refractive index curve obtained in the ninth embodiment and the characteristics of the input pump pulse light, the center wavelength of the parametric gain that changes with respect to the center wavelength of the pump pulse light was obtained. Further, on the Slow axis orthogonal to the Fast axis of the nonlinear optical waveguide, a wavelength having the same group velocity as the center wavelength of the input pump pulse light was obtained. By inputting pump pulsed light having a center wavelength of 1035 nm to the Fast axis, a parametric gain having a center wavelength of 750 nm can be obtained on the Slow axis, and the group velocities match.

Therefore, in the present embodiment, the signal pulse light source 209 outputs a signal pulse light having a center wavelength of 750 nm. The signal pulsed light having a central wavelength of 750 nm is input to another input port of the optical combiner 207, which is a polarization beam combiner. Then, the signal pulsed light is input to the nonlinear optical waveguide 208 that produces a parametric gain. Here, the signal pulsed light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the slow axis of the nonlinear optical waveguide 208.

The signal pulse light is synchronized with the pump pulse light, is combined with the pump pulse light by the optical combiner 207, and is input to one end of the nonlinear optical waveguide 208. By inputting the signal pulse light in synchronization with the pump pulse light, the signal pulse light is amplified by the parametric gain in the nonlinear optical waveguide 208. Further, in the non-linear optical waveguide 208, since the group velocity of the pump pulse light and the group velocity of the signal pulsed light match, both pulsed lights propagate without walking off and the signal pulsed light is amplified.

As the light having a center wavelength of 750 nm, which is the signal pulse light, the light generated as follows was used. The pulsed light of 1550 nm, which is the output of the Er fiber laser, was widened. Then, the light obtained by cutting out 1500 nm from the widebanded light with a wavelength filter was wavelength-converted to 750 nm by PPLN to obtain signal pulsed light. However, the light having a center wavelength of 750 nm is not limited to this form, and may be a semiconductor laser output or a Ti: Sapphire laser output.

When the pump pulse light and the signal pulse light have the same polarization axis, there is a group velocity difference of about 2 ps / m between 1035 nm and 750 nm. Therefore, in this case, in the vicinity of the peak of the pulse width of 0.8 ps (1/10 of the full width at half maximum of the time), the walk-off occurs at about 0.04 m. However, according to this embodiment, the pump pulse light and the signal pulse light of 0.04 m or more can be propagated in an overlapping manner, and the signal pulse light having a center wavelength of 750 nm can be greatly amplified.

[16th Embodiment]
The light source device according to the 16th embodiment of the present invention will be described.
The light source device according to the sixteenth embodiment constitutes an OPO and has the same configuration as shown in FIG. 5 as the second embodiment. However, in the light source device according to the 16th embodiment, the pump pulse light source 201, the optical combiner 207 which is the first polarization beam combiner, and the nonlinear optical waveguide 208 are the same as those in the 15th embodiment.

The other end, which is the output end of the nonlinear optical waveguide 208, is optically connected to the optical separator 401, which is the second polarization beam combiner, as in the second embodiment. The optical separator 401 separates the residual pump pulsed light from the light generated by the parametric gain, as in the second embodiment.

As in the second embodiment, a part of the light generated by the parametric gain is taken out as output light by the optical take-out device 402 which is an optical fiber coupler. The remaining portion of the light generated by the parametric gain is input to the optical combiner 207, which is the first polarization beam combiner, as in the second embodiment.

Similar to the second embodiment, an optical delayer 404 is inserted between the optical ejector 402 and the optical combiner 207, and by controlling the optical delayer 404, a pump pulse that is repeatedly input. The light and the light generated by the parametric gain are superimposed in synchronization at the same timing.
According to this embodiment, a resonator is configured, and a high output wavelength conversion output of 750 nm can be obtained.

[17th Embodiment]
The light source device according to the seventeenth embodiment of the present invention will be described.
The light source device according to the seventeenth embodiment constitutes OPA and has the same configuration as shown in FIG. 2 as in the first embodiment, but the pump pulse light source 201 and the signal pulse light source 209 are described below. It is different from the first embodiment. Further, as the nonlinear optical waveguide 208 that produces optical parametric amplification, an optical fiber similar to the optical fiber used in the ninth embodiment was used.

In the seventeenth embodiment, the pump pulse light source 201 outputs pump pulse light having a center wavelength of 1530 nm, an average power of 15 W, a repeating light frequency of 40 MHz, and a pulse time width of 1 ps. In the pump pulse light source 201, the light high output by the mode lock fiber laser using the erbium (Er) -doped optical fiber and the optical fiber amplifier is widened by the high nonlinear optical fiber. An output is obtained by cutting out light in a predetermined wavelength range from the widebanded light with a wavelength filter and setting the center wavelength of the cut-out spectrum to 1530 nm. Then, the output is amplified by an optical fiber amplifier using an Er-doped optical fiber. In this way, the pump pulsed light having the output characteristics as described above is obtained.

However, the pump pulse light source 201 is not limited to the above configuration, and may be one that generates 1530 nm from another fiber laser and amplifies and outputs the light. Alternatively, the output of the laser diode (LD) may be modulated to output pulsed light, or a mode lock laser other than a fiber laser may be used. Alternatively, a tunable laser in which a tunable filter is provided in the resonator of a mode lock laser using an Er-doped optical fiber may be used.

The pump pulse light output from the pump pulse light source 201 is input to one input port of the optical combiner 207 which is a polarization beam combiner. Then, the pump pulse light input to the optical combiner 207 is input to one end of the nonlinear optical waveguide 208 that causes optical parametric amplification. Here, unlike the first embodiment, in the present embodiment, the pump pulse light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the Fast axis of the nonlinear optical waveguide 208.

From the effective refractive index curve obtained in the ninth embodiment and the characteristics of the input pump pulse light, the center wavelength of the parametric gain that changes with respect to the center wavelength of the pump pulse light was obtained. Further, on the Slow axis orthogonal to the Fast axis of the nonlinear optical waveguide, a wavelength having the same group velocity as the center wavelength of the input pump pulse light was obtained. By inputting pump pulse light having a center wavelength of 1530 nm to the Fast axis, a parametric gain having a center wavelength of 1600 nm can be obtained on the Slow axis, and the group velocities match.

Therefore, in the present embodiment, the signal pulse light source 209 outputs a signal pulse light having a center wavelength of 1600 nm. The signal pulsed light having a central wavelength of 1600 nm is input to another input port of the optical combiner 207 which is a polarization beam combiner. Here, the signal pulsed light is input to one end of the nonlinear optical waveguide 208 so that its polarization axis coincides with the slow axis of the nonlinear optical waveguide 208.

The signal pulse light is synchronized with the pump pulse light, is combined with the pump pulse light by the optical combiner 207, and is input to one end of the nonlinear optical waveguide 208. By inputting the signal pulse light in synchronization with the pump pulse light, the signal pulse light is amplified by the parametric gain in the nonlinear optical waveguide 208. Further, in the non-linear optical waveguide 208, since the group velocity of the pump pulse light and the group velocity of the signal pulsed light match, both pulsed lights propagate without walking off and the signal pulsed light is amplified.

As the signal pulsed light having a central wavelength of 1600 nm, light obtained by shifting the pulsed light having a central wavelength of 1550 nm, which is an Er fiber laser output, by a long wavelength was used. However, the light having a center wavelength of 1600 nm is not limited to this form, and the pulsed light having a center wavelength of 1550 nm, which is an Er fiber laser output, may be widened to a wide band, and the light cut out from 1600 nm by a wavelength filter may be used, or may be a semiconductor laser output. good.

When the pump pulse light and the signal pulse light have the same polarization axis, there is a group velocity difference of about 10 ps / m between 1530 nm and 1600 nm. Therefore, in this case, in the vicinity of the peak of the pulse width of 1 ps (1/10 of the full width at half maximum of the time), the walk-off occurs at about 0.01 m. However, according to this embodiment, it is possible to superimpose and propagate the pump pulse light and the signal pulse light of 0.01 m or more, and it is possible to greatly amplify the signal pulse light having a center wavelength of 1600 nm.

A second polarization beam combiner is used as a polarization beam splitter at the other end of the nonlinear optical waveguide 208, which is the output end of the light source device, in addition to the first polarization beam combiner used as the optical combiner 207. May be connected for. The second polarized beam combiner separates the remaining pump pulsed light, which remains unconverted by the optical parametric effect, from the light generated by the parametric gain. As a result, it is possible to reduce or eliminate the influence of XPM generated in other than the nonlinear optical waveguide 208, and it is possible to suppress the distortion of light generated by the parametric gain.

Further, the first and second polarization beam combiners may be fiber couplers or WDM couplers. Alternatively, a spatial optical system using a polarization beam splitter or a dichroic mirror may be used. This makes it possible to reduce the wavelength-dependent characteristics of the polarization beam combiner.

[18th Embodiment]
The light source device according to the eighteenth embodiment of the present invention will be described.
The light source device according to the eighteenth embodiment constitutes an OPO and has the same configuration as shown in FIG. 5 as the second embodiment. However, in the eighteenth embodiment, the pump pulse light source 201, the optical combiner 207 which is the first polarization beam combiner, and the nonlinear optical waveguide 208 are the same as those in the seventeenth embodiment.

The other end, which is the output end of the nonlinear optical waveguide 208, is optically connected to the optical separator 401, which is the second polarization beam combiner, as in the second embodiment. The optical separator 401 separates the residual pump pulsed light from the light generated by the parametric gain, as in the second embodiment.

As in the second embodiment, a part of the light generated by the parametric gain is taken out as output light by the optical take-out device 402 which is an optical fiber coupler. The remaining portion of the light generated by the parametric gain is input to the optical combiner 207, which is the first polarization beam combiner, as in the second embodiment.

An optical delayer 404 is inserted between the optical ejector 402 and the optical combiner 207, and by controlling the optical delayer 404, the repeatedly input pump pulse light and the light generated by the parametric gain can be obtained. Synchronize and stack at the same timing.
According to this embodiment, a resonator is configured, and a high-output wavelength conversion output having a wavelength of 1600 nm can be obtained.

[19th Embodiment]
The light source device according to the nineteenth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a diagram illustrating a light source device according to a nineteenth embodiment.

The light source device according to the nineteenth embodiment constitutes OPA and has the same basic configuration as that of the first embodiment. Further, the light source device according to the 19th embodiment polarizes the pump pulse light and the signal pulse light combined by the optical combiner 207 by 90 degrees as shown in FIG. 11 in the light source device according to the first embodiment. It has a polarization rotation mechanism 501 that can be rotated.

The polarization rotation mechanism 501 functions as a polarization rotation unit, and is provided between the optical combiner 207, which is a polarization beam combiner, and the nonlinear optical waveguide 208, which provides a parametric gain. The pump pulse light and the signal pulse light that are combined by the optical combiner 207 and output from the output port are input to one end of the nonlinear optical waveguide 208 after the polarization is rotated by 90 degrees by the polarization rotation mechanism 501.

In the polarization rotation mechanism 501, for example, the output port that outputs the combined pump pulse light and signal pulse light of the optical combiner 207 is brought into contact with one end of the nonlinear optical waveguide 208 that is an optical fiber, and at least one of them is physically connected. It has a rotating configuration. Alternatively, the polarization rotation mechanism 501 may have the following configuration. That is, the polarization rotation mechanism 501 has a first lens whose parallel beam is the light output from the output port that outputs the combined light of the optical combiner 207, and a non-linear optical waveguide 208 that collects the parallel beam. A spatial optical system having a second lens to be input at one end is configured. The polarization rotation mechanism 501 has a mechanism for rotating polarized light, such as a half-wave plate, inserted between the first lens and the second lens, and is combined by the optical combiner 207 by this mechanism. The polarized light of the waved pump pulsed light and the signal pulsed light is rotated.

In the light source device according to the nineteenth embodiment, the polarization rotation mechanism 501 switches between the first case and the second case in which the birefringence axes of the nonlinear optical waveguide 208 propagating the pump pulse light and the signal pulse light are different from each other. Both pulsed lights can be input to the non-linear optical waveguide 208. That is, in the first case, the pump pulse light is input to the slow axis of the nonlinear optical waveguide 208, while the signal pulse light is input to the fast axis of the nonlinear optical waveguide 208. The second case is a case where the pump pulse light is input to the Fast axis of the nonlinear optical waveguide 208, while the signal pulse light is input to the Slow axis of the nonlinear optical waveguide 208. The polarization rotation mechanism 501 can switch between the first case and the second case according to the wavelength bands of the pump pulse light and the signal pulse light.

As the pump pulse light source 201, the same light source as in the first embodiment was used. That is, the pump pulse light source 201 outputs pump pulse light having a center wavelength of 1020 nm to 1080 nm, an average power of 5 W, a repeating light frequency of 40 MHz, and a pulse time width of 1 ps. The pump pulse light source 201 widens the light output by the mode-lock fiber laser 202 using the ytterbium (Yb) -doped optical fiber and the optical fiber amplifier 203 by the highly nonlinear optical fiber 204. Then, by cutting out by the wavelength filter 205, light in a predetermined wavelength range is cut out from the light band widened by the highly nonlinear optical fiber 204. The light cut out by the wavelength filter 205 is amplified by the optical fiber amplifier 206 to increase the output, and then is output as pump pulse light. The pump pulse light source 201 is configured as a tunable light source capable of changing the wavelength of the pump pulse light. However, the pump pulse light source 201 is not limited to the above configuration, and may be one that amplifies and outputs light generated from another fiber laser. Alternatively, the output of the laser diode (LD) may be modulated to output pulsed light, or a mode lock laser other than a fiber laser may be used.

As shown in FIG. 4, consider a case where the pump pulsed light is input to the nonlinear optical waveguide with the center wavelength changed from 1020 nm to 1080 nm. In this case, when the pump pulse light is input so that the polarization axis coincides with the Slow axis of the nonlinear optical waveguide and the signal pulse light is input so as to coincide with the Fast axis of the nonlinear optical waveguide, the center wavelength ranges from 655 nm to 775 nm. Parametric gain spectrum is obtained. On the other hand, when the pump pulse light is input so that the polarization axis coincides with the Fast axis of the nonlinear optical waveguide and the signal pulse light is input so as to coincide with the Slow axis of the nonlinear optical waveguide, the center wavelength ranges from 725 nm to 1000 nm. Parametric gain spectrum of.

Therefore, in the present embodiment, the output light output from the light source device is monitored, and the birefringence axis through which the pump pulse light and the signal pulse light propagate is switched based on the monitoring result. As a configuration for this purpose, the light source device according to the present embodiment further includes an optical take-out device 502, an optical spectrum analyzer 503, and a control unit 504.

The light take-out device 502 is optically connected to the other end of the nonlinear optical waveguide 208 from which the output light of the light source device is output. The optical take-out device 502 takes out a part of the output light and inputs it to the optical spectrum analyzer 503. As the optical take-out device 502, an optical fiber coupler or the like can be used.

The optical spectrum analyzer 503 monitors the wavelength of the signal pulsed light based on a part of the output light input from the optical extractor 502. The optical spectrum analyzer 503 outputs a signal corresponding to the wavelength of the signal pulsed light and inputs it to the control unit 504.

Based on the signal input from the optical spectrum analyzer 503, the control unit 504 controls the operation of the polarization rotation mechanism 501 and the pump pulse light source 201 according to the wavelength of the signal pulsed light as follows.

When the central wavelength of the signal pulsed light is 655 nm or more and less than 750 nm, the control unit 504 controls the operation of the polarization rotation mechanism 501 and the pump pulse light source 201 as follows. First, the control unit 504 inputs the pump pulse light to the Slow axis of the nonlinear optical waveguide 208 so that the polarization axes coincide with each other, and the signal pulse light to the Fast axis of the nonlinear optical waveguide 208 so that the polarization axes coincide with each other. It controls the operation of the polarization rotation mechanism 501. Then, the control unit 504 controls the operation of the pump pulse light source 201 so as to output the pump pulse light having a central wavelength in the wavelength band of 1020 nm to 1070 nm so that the wavelength of the pump pulse light matches the wavelength of the signal pulse light. ..

On the other hand, when the central wavelength of the signal pulsed light is 750 nm or more and 1000 nm or less, the control unit 504 controls the operation of the polarization rotation mechanism 501 and the pump pulse light source 201 as follows. First, the control unit 504 inputs the pump pulse light to the Fast axis of the nonlinear optical waveguide 208 so that the polarization axes coincide with each other, and the signal pulse light to input the signal pulse light to the Slow axis of the nonlinear optical waveguide 208 so that the polarization axes coincide with each other. It controls the operation of the polarization rotation mechanism 501. Then, the control unit 504 controls the operation of the pump pulse light source 201 so as to output the pump pulse light having a central wavelength in the wavelength band of 1030 nm to 1080 nm so that the wavelength of the pump pulse light matches the wavelength of the signal pulse light. .. In the present embodiment, the switching wavelength is 750 nm, which is the central wavelength of 725 nm to 775 nm, which overlaps 655 nm to 775 nm and 725 nm to 1000 nm of the parametric gain band obtained depending on the polarization axes of the pump pulse light and the signal pulse light. However, any wavelength may be selected as the switching wavelength as long as the parametric gain bands overlap between 725 nm and 775 nm.

According to this embodiment, the parametric gain wavelength band can be extended to the short wavelength side and the long wavelength side, and a wide band signal pulsed light can be amplified.

[20th Embodiment]
The light source device according to the twentieth embodiment of the present invention will be described with reference to FIG. FIG. 12 is a diagram illustrating a light source device according to a twentieth embodiment.

The light source device according to the twentieth embodiment constitutes an OPO and has the same basic configuration as that of the second embodiment. Further, the light source device according to the twentieth embodiment has the same polarization rotation mechanism 501 as the nineteenth embodiment.

In this embodiment, the polarization rotation mechanism 501 is provided as follows. That is, the polarization rotation mechanism 501 is provided between the nonlinear optical waveguide 208 and the optical separator 401. The other end, which is the output end of the nonlinear optical waveguide 208, is optically connected to the optical separator 401, which is the second polarization beam combiner, via the polarization rotation mechanism 501. The optical separator 401 separates the residual pump pulsed light from the light generated by the parametric gain, as in the second embodiment.

The polarization rotation mechanism 501 provided between the non-linear optical waveguide 208 and the optical separator 401 polarizes the combined pump pulse light and signal pulse light output from the other end of the non-linear optical waveguide 208 by 90 degrees. It is possible to rotate it. The polarization rotation mechanism can have the same configuration as that of the nineteenth embodiment. Further, the polarization rotation mechanism 501 remains in the optical separator 401, which is the second polarization beam combiner, in accordance with the polarization axis of the pump pulse light input to the optical combiner 207, which is the first polarization beam combiner. The pump pulse light is controlled to be extracted.

Part of the light generated by the parametric gain in the nonlinear optical waveguide 208 is taken out as output light by the optical take-out device 402 which is an optical fiber coupler. The remaining portion of the light produced by the parametric gain is input through the optical delayer 404 to the optical combiner 207, which is the first polarization beam combiner. By controlling the optical delayer 404, the repeatedly input pump pulsed light and the light generated by the parametric gain are synchronized and superposed at the same timing.

Further, in the present embodiment, the polarization of the signal pulsed light having a central wavelength of 655 nm to 775 nm or 725 nm to 1000 nm generated by the non-linear optical waveguide 208 is polarized by the polarization rotation mechanism 501 before being input to the optical combiner 207. Rotate. Thereby, the parametric gain wavelength can be controlled by controlling the case where the signal pulse light coincides with the pump pulse light and the case where the polarization axes are orthogonal to each other.

The parametric gain wavelength can be controlled by using, for example, the same optical take-out device 502, optical spectrum analyzer 503, and control unit 504 as in the nineteenth embodiment. In this case, the optical extraction device 502 extracts a part of the output light output from the optical extraction device 402 and inputs it to the optical spectrum analyzer 503.

The optical spectrum analyzer 503 monitors the wavelength of the signal pulsed light based on a part of the output light input from the optical extractor 502. The optical spectrum analyzer 503 outputs a signal corresponding to the wavelength of the signal pulsed light and inputs it to the control unit 504.

The control unit 504 controls the operation of the polarization rotation mechanism 501 according to the wavelength of the signal pulsed light based on the signal input from the optical spectrum analyzer 503. In this way, the parametric gain wavelength can be controlled.

According to this embodiment, a resonator is configured and a high output wavelength conversion output can be obtained. Further, a wide band tunable band can be obtained.

[21st Embodiment]
The light source device according to the 21st embodiment of the present invention will be described with reference to FIG. FIG. 13 is a diagram illustrating a light source device according to the 21st embodiment.

The light source device according to the 21st embodiment constitutes OPA and has the same basic configuration as the 1st embodiment. However, in the light source device according to the 21st embodiment, a WDM coupler is used as the optical combiner 207 instead of the polarization beam combiner, and the pump pulse light and the signal pulse light are combined by the WDM coupler. Here, the optical combiner 207 is not limited to the WDM coupler, and may be a spatial optical system using a dichroic mirror. As the WDM coupler or the like used as the optical combiner 207, one having no polarization-dependent characteristics is selected. This makes it possible to combine the pump pulse light and the signal pulse light with arbitrary polarization and input them to the nonlinear optical waveguide 208.

Further, as shown in FIG. 13, the light source device according to the 21st embodiment is a polarization rotation that controls the polarization of the pump pulse light between the output end of the pump pulse light source 201 and the optical combiner 207 which is a WDM coupler. A mechanism 501-1 is provided. The polarization rotation mechanism 501-1 is provided immediately before one input port of the optical combiner 207.

Further, a polarization rotation mechanism 501-2 for controlling the polarization of the signal pulse light is provided between the output end of the signal pulse light source 209 and the optical combiner 207 which is a WDM coupler. The polarization rotation mechanism 501-2 is provided immediately before another input port of the optical combiner 207.

The polarization rotation mechanisms 501-1 and 501-2 function as the polarization rotation unit, and can have the same configuration as the polarization rotation mechanism 501 described in the nineteenth embodiment. The polarization rotation mechanism 501-1 has, for example, a configuration in which an input port into which the pump pulse light of the optical combiner 207 is input and an output end of the pump pulse light source 201 are brought into contact with each other to physically rotate at least one of them. ing. Further, the polarization rotation mechanism 501-2 physically rotates at least one of the signal pulse light sources 209 by bringing another input port into which the signal pulse light of the optical combiner 207 is input into contact with the output end of the signal pulse light source 209. It has a configuration. Alternatively, the polarization rotation mechanisms 501-1 and 501-2 may have the following configurations. That is, the polarization rotation mechanisms 501-1 and 501-2 have a first lens that uses light output from a light source as a parallel beam, and a second lens that collects the parallel beam and inputs the parallel beam to the input port of the optical combiner 207. It constitutes a spatial optical system having a lens of. The polarization rotation mechanisms 501-1 and 501-2 have a mechanism for rotating polarized light, such as a half-wave plate, inserted between the first lens and the second lens. The polarization of the pump pulsed light or signal pulsed light output from the light source is rotated. With such polarization rotation mechanisms 501-1 and 501-2, the combination of the polarization directions of the pump pulse light and the signal pulse light can be variously changed and input to the nonlinear optical waveguide 208.

According to this embodiment, the parametric gain spectrum can be changed by the combination of the polarization axes of the nonlinear optical waveguide 208 in which the pump pulse light and the signal pulse light propagate. Then, the wavelength of the signal pulsed light amplified by the optical parametric amplification can be selected without changing the wavelength of the pump pulsed light. Further, by controlling the wavelength of the pump pulse light, it is possible to change the parametric gain spectrum over a wide band.

[22nd Embodiment]
The light source device according to the 22nd embodiment of the present invention will be described with reference to FIG. FIG. 14 is a diagram illustrating a light source device according to the 22nd embodiment.

The light source device according to the 22nd embodiment constitutes an OPO and has the same basic configuration as the 2nd embodiment. However, in the light source device according to the 22nd embodiment, as in the 21st embodiment, the first WDM coupler is used as the optical combiner 207 instead of the first polarization beam combiner. Further, as the optical separator 401, a second WDM coupler is used instead of the second polarized beam combiner. The optical combiner 207 and the optical separator 401 are not limited to WDM couplers, respectively, and may be a spatial optical system using a dichroic mirror.

Further, as shown in FIG. 14, the light source device according to the 22nd embodiment controls the polarization of the pump pulse light between the output end of the pump pulse light source 201 and the optical combiner 207 which is the first WDM coupler. A polarization rotation mechanism 501-1 is provided. Further, a polarization rotation mechanism 501-2 for controlling the polarization of the signal pulsed light is provided between the output end of the optical delayer 404 and the optical combiner 207 which is the first WDM coupler. The polarization rotation mechanisms 501-1 and 501-2 can have the same configuration as that of the 21st embodiment.

In the present embodiment, the residual pump pulsed light is separated and taken out by the optical separator 401 which is the second WDM coupler. Part of the light generated by the parametric gain in the nonlinear optical waveguide 208 is taken out as output light by the optical take-out device 402 which is an optical fiber coupler. The remaining portion of the light generated by the parametric gain is input to the optical combiner 207, which is the first WDM coupler, through the optical delayer 404. By controlling the optical delayer 404, the repeatedly input pump pulsed light and the light generated by the parametric gain are synchronized and superposed at the same timing.

Further, in the present embodiment, the light having a central wavelength of 655 nm to 775 nm or 725 nm to 1000 nm generated by the nonlinear optical waveguide 208 is input to the optical combiner 207 by rotating the polarized light by the polarization rotation mechanism 501-2. can do. Further, the pump pulse light can be input to the optical combiner 207 by rotating the polarized light by the polarization rotation mechanism 501-1. Thus, in the present embodiment, the parametric gain wavelength can be controlled by controlling the polarization axes of the optical waveguide to which the signal pulse light and the pump pulse light are input.

According to this embodiment, a resonator is configured and a high output wavelength conversion output can be obtained. Further, a wide band tunable band can be obtained.

[23rd Embodiment]
The light source device according to the 23rd embodiment of the present invention will be described.
The light source device according to the 23rd embodiment has the same configuration as that of the 22nd embodiment. However, in the light source device according to the 23rd embodiment, the WDM couplers used as the optical combiner 207 and the optical separator 401 combine and branch light having a wavelength of less than 1100 nm and light having a wavelength of 1100 nm or more, respectively. I made it.

When the pump pulse light is input to the nonlinear optical waveguide with the center wavelength changed from 1020 nm to 1080 nm, when the pump pulse light and the signal pulse light propagate on the same axis, a parametric gain spectrum having a center wavelength of about 2042 nm to 1580 nm can be obtained. .. Further, when the pump pulse light and the signal pulse light propagate orthogonally, a parametric gain spectrum having a center wavelength of about 1715 nm to 1168 nm can be obtained.

Light having a central wavelength of 2042 nm to 1580 nm or 1715 nm to 1168 nm generated by the nonlinear optical waveguide 208 can be input to the optical combiner 207 by rotating the polarized light by the polarization rotation mechanism 501-2. In this way, the parametric gain wavelength can be controlled by controlling the signal pulse light when the pump pulse light and the polarization axis coincide with each other and when they are orthogonal to each other.

According to this embodiment, a resonator is configured and a high output wavelength conversion output can be obtained. Further, a wide band tunable band can be obtained.

[24th Embodiment]
The light source device according to the 24th embodiment of the present invention will be described with reference to FIG. FIG. 15 is a diagram illustrating a light source device according to the 24th embodiment.

The light source device according to the 24th embodiment is the light source device according to the 3rd embodiment, further provided with an intensity modulator 601 that functions as an intensity adjusting unit for adjusting the intensity of the pump pulse light, as shown in FIG. Is. The intensity modulator 601 is provided between the pump pulse light source and the optical combiner 207 which is a polarization beam combiner.

As the intensity modulator 601, an attenuator with variable transmittance was used. However, the intensity modulator 601 is not limited to this. As the intensity modulator 601, a variable intensity modulator can be used. For example, an intensity modulator based on a modulation method utilizing an electro-optical effect may be used, or an optical amplifier having a variable amplification factor may be used. An optical amplifier having a variable amplification factor can adjust the amplification intensity by, for example, the excitation energy input to the optical amplifier. Further, since the peak power of the pump pulse light may be controlled, the intensity modulator 601 may be a mechanism that controls the chirp of the pump pulse light to change the pulse width. For example, the intensity modulator 601 is provided with a circulator and a reflective chirp fiber Bragg grating (CFBG), and uses a chirp adjusting mechanism or the like that stretches the CFBG to control the chirp amount and adjusts the chirp amount of the pump pulse light. But it's okay.

Further, in the present embodiment, the wavelength of the signal pulsed light is monitored, and the operation of the intensity modulator 601 is controlled based on the monitoring result. As a configuration for this purpose, the light source device according to the present embodiment further includes an optical extraction device 602, an optical spectrum analyzer 603, and a control unit 604.

The light take-out device 602 is provided between the signal pulse light source 209 and the optical combiner 207 which is a polarization beam combiner. As the optical take-out device 602, an optical fiber coupler or the like can be used. The optical take-out device 602 extracts a part of the signal pulsed light and inputs it to the optical spectrum analyzer 603.

The optical spectrum analyzer 603 monitors the wavelength of the signal pulsed light based on a part of the signal pulsed light input from the optical extractor 602. The optical spectrum analyzer 603 outputs a signal corresponding to the wavelength of the signal pulsed light and inputs it to the control unit 604. A spectroscope may be used instead of the optical spectrum analyzer 603.

The control unit 604 controls the operation of the intensity modulator 601 and the pump pulse light source 201 according to the wavelength of the signal pulsed light based on the signal input from the optical spectrum analyzer 603.

From Equation 10 and Equation 11, it is possible to change the parametric gain wavelength by modulating the peak intensity of the pump pulse light.

Therefore, in the present embodiment, the wavelength of the input signal pulse light is monitored by the optical spectrum analyzer 603, and when the wavelength changes, the control unit 604 controls the operation of the intensity modulator 601 and the pump pulse light source 201. To do. Thereby, the intensity and wavelength of the pump pulse light are adjusted. That is, the intensity of the pump pulse light is adjusted by the intensity modulator 601 so as to generate a parametric gain wavelength in which the group velocities match. Furthermore, by adjusting the wavelength of the pump pulse light, the group velocities can be matched.

According to this embodiment, even if the wavelength of the signal pulse light fluctuates, the signal pulse light can be greatly amplified by adjusting the intensity and wavelength of the pump pulse light as described above.

The extraction of the signal pulsed light for monitoring the wavelength of the signal pulsed light is not limited to the extraction by the coupler before the input to the optical combiner 207. In addition, a part of the output light output from the light source device may be taken out and monitored by an optical spectrum analyzer.
It should be noted that this embodiment can be applied not only to the third embodiment but also to other embodiments.

[25th Embodiment]
The light source device according to the 25th embodiment of the present invention will be described with reference to FIG. FIG. 16 is a diagram illustrating a light source device according to the 25th embodiment.

The light source device according to the 25th embodiment is the light source device according to the 4th embodiment, further provided with an intensity modulator 601 for adjusting the intensity of the pump pulse light, as shown in FIG. The intensity modulator 601 is as described in the 24th embodiment.

Since the light source device constituting the OPO has a resonator structure, the generated parametric gain wavelength also changes when the wavelength of the pump pulse light fluctuates. Therefore, by controlling the intensity of the pump pulse light, the parametric gain wavelength can be controlled so that the wavelength at which the parametric gain wavelength and the group velocity match can be matched.

In the present embodiment, the intensity of the pump pulse light is adjusted based on the intensity of the amplified signal pulse light output from the light source device. As a configuration for this purpose, the light source device according to the present embodiment further includes a light take-out device 702, an intensity meter 703, and a control unit 704.

The light take-out device 702 is provided at the output end of the light take-out device 402 from which the output light of the light source device is output. As the optical take-out device 702, an optical fiber coupler or the like can be used. The light take-out device 702 takes out a part of the output light output from the light take-out device 402 and inputs it to the intensity meter 703.

The intensity meter 703 monitors the intensity of the signal pulsed light based on a part of the output light input from the light extractor 702. The intensity meter 703 outputs a signal corresponding to the intensity of the signal pulsed light and inputs it to the control unit 704.

The control unit 704 controls the operation of the intensity modulator 601 according to the intensity of the signal pulsed light based on the signal input from the intensity meter 703.

In the present embodiment, the intensity of the signal pulsed light is monitored by the intensity meter 703. When the intensity of the signal pulse light decreases, the control unit 704 determines that the group velocities do not match, and controls the operation of the intensity modulator 601 to adjust the intensity of the pump pulse light.

According to this embodiment, even if the wavelength of the pump pulse light fluctuates, the signal pulse light can be greatly amplified by adjusting the intensity of the pump pulse light.
This embodiment can be applied not only to the fourth embodiment but also to other embodiments.

[26th Embodiment]
The light source device according to the 26th embodiment of the present invention will be described with reference to FIG. FIG. 17 is a diagram illustrating a light source device according to the 26th embodiment.

The light source device according to the 26th embodiment is further provided with a configuration for adjusting the wavelength of the pump pulse light in the light source device according to the 4th embodiment.

Since the light source device constituting the OPO has a resonator structure, the generated parametric gain wavelength also changes when the intensity of the pump pulse light fluctuates. Therefore, by controlling the wavelength of the pump pulse light, the parametric gain wavelength can be controlled so that the wavelength at which the parametric gain wavelength and the group velocity match can be matched.

In the present embodiment, the wavelength of the pump pulse light is adjusted based on the intensity of the amplified signal pulse light output from the light source device. As a configuration for this purpose, the light source device according to the present embodiment further includes a light take-out device 702, an intensity meter 703, and a control unit 704.

The light take-out device 702 is provided at the output end of the light take-out device 402 from which the output light of the light source device is output. As the optical take-out device 702, an optical fiber coupler or the like can be used. The light take-out device 702 takes out a part of the output light output from the light take-out device 402 and inputs it to the intensity meter 703.

The intensity meter 703 monitors the intensity of the signal pulsed light based on a part of the output light input from the light extractor 702. The intensity meter 703 outputs a signal corresponding to the intensity of the signal pulsed light and inputs it to the control unit 704.

Unlike the 25th embodiment, the control unit 704 controls the operation of the pump pulse light source 201 according to the intensity of the signal pulse light based on the signal input from the intensity meter 703.

In the present embodiment, the intensity of the signal pulsed light is monitored by the intensity meter 703. When the intensity of the signal pulse light is reduced, the control unit 704 determines that the group velocities do not match, and controls the operation of the pump pulse light source 201 to adjust the wavelength of the pump pulse light.

According to this embodiment, even if the intensity of the pump pulse light fluctuates, the signal pulse light can be greatly amplified by adjusting the wavelength of the pump pulse light.
This embodiment can be applied not only to the fourth embodiment but also to other embodiments.

[27th Embodiment]
In the above-described first to 26th embodiments, since a nonlinear optical waveguide having orthogonal polarization axes is used, the pump pulse light and the signal pulse light are polarized at approximately 90 degrees so as to propagate along the respective axes. Was entered in a different state. However, in photonic crystal fiber (PCF) and the like, there are also optical fibers having different propagation axes every 30 degrees or 60 degrees. When such an optical fiber is used as a nonlinear optical waveguide, the nonlinear optical waveguide that produces a parametric gain is a nonlinear optical waveguide having at least two or more propagation axes. In such a case, the parametric gain wavelength can be changed by having the same configuration as that described in the 21st embodiment and controlling the polarization axes of the input pump pulse light and the signal pulse light.

[28th Embodiment]
The information acquisition device according to the 28th embodiment will be described with reference to FIG. FIG. 18 is a diagram illustrating an information acquisition device according to the 28th embodiment. In the 28th embodiment, an SRS microscope that detects and performs imaging by detecting induced Raman scattering (SRS) as an information acquisition device that acquires information on a measurement target that is a subject will be described.

The information acquisition device 2000 according to the 28th embodiment, which is an SRS microscope, has a light source unit 2001 that emits two pulsed lights having different center wavelengths and an irradiation unit that irradiates the measurement target 1016 with the light emitted from the light source unit 2001. It has 2002 and. In addition, the information acquisition device 2000 has a detection unit 2003 that detects light from the measurement target 1016 irradiated with light by the irradiation unit 2002. Further, the information acquisition device 2000 has a PC 1022 that functions as a processing device that forms an image based on the detection result of the detection unit 2003.

The light source unit 2001 includes a seed light source 1001, a Yb-doped optical fiber amplifier 1002, a polarization-maintaining photonic crystal fiber 1003, an isolator 1004, and an optical fiber coupler 1005.

Further, the light source unit 2001 includes a wavelength filter 1006, a Yb-doped optical fiber amplifier 1007, a repetition frequency multiplier 1010, a Yb-doped optical fiber amplifier 1011 and an OPO 1012 as a configuration for obtaining the first pulsed light. ing. The OPO 1012 is a light source device according to the twelfth embodiment.

Further, the light source unit 2001 includes a wavelength variable filter 1008, a Yb-doped optical fiber amplifier 1009, and an optical delayer 1017 as a configuration for obtaining a second pulsed light having a center wavelength different from that of the first pulsed light. doing.

The seed light source 1001 is a Yb fiber laser and outputs output light having a center wavelength of 1030 nm, a spectrum width of 8 nm, an output of 10 mW, and a repetition frequency of 40 MHz.

The output light from the seed light source 1001 propagates through the Yb-doped optical fiber amplifier 1002, and the spectral width is widened to 30 nm. Further, the output of the output light is 150 mW by the Yb-doped optical fiber amplifier 1002.

The output light of the Yb-doped optical fiber amplifier 1002 propagates through the fused polarization-holding photonic crystal fiber 1003 (LMA-PM-5, NKT Photonics) having a length of 3 m, and the wavelength band is extended to 1010 nm to 1080 nm. The output light then propagates through the isolator 1004 and is split in two by the optical fiber coupler 1005.

The first pulsed light, which is one of the lights branched by the optical fiber coupler 1005, has a center wavelength of 1060 nm through the wavelength filter 1006 and the Yb-doped optical fiber amplifier 1007.

The second pulsed light, which is another of the light branched by the optical fiber coupler 1005, has a variable characteristic of a center wavelength of 1020 nm to 1070 nm through a wavelength variable filter 1008 and a Yb-doped optical fiber amplifier 1009.

The first pulsed light is a pulsed light train having a repeating frequency of 80 MHz by the repeating frequency multiplier 1010. The repetition frequency multiplier 1010 has, for example, a configuration in which the first pulsed light is branched by an optical fiber coupler, and one of them is shifted by a half cycle and recombined. Then, the output light of the repetition frequency multiplier 1010 is input to the Yb-doped optical fiber amplifier 1011 and amplified. The light amplified by the Yb-doped optical fiber amplifier 1011 is input to the OPO 1012 according to the twelfth embodiment. In this way, the OPO 1012 obtains output light having a central wavelength of 800 nm as the first pulsed light.

The light source unit 2001 further has a dichroic mirror 1013. The second pulsed light having a wavelength variable characteristic of a central wavelength of 1020 nm to 1070 nm and the first pulsed light having a central wavelength of 800 nm are combined by the dichroic mirror 1013 and output from the light source unit 2001. The light output from the light source unit 2001 is input to the irradiation unit 2002.

The irradiation unit 2002 includes an XY scanning mirror 1014 and an irradiation objective lens 1015.

The irradiation direction of the first pulsed light and the second pulsed light input from the light source unit 2001 to the irradiation unit 2002 is controlled by the XY scanning mirror 1014, and the measurement target 1016 is irradiated through the irradiation objective lens 1015. To. At least one of the first pulsed light and the second pulsed light propagates through the optical delayer to adjust the timing so that they are superposed in time. For example, in the configuration shown in FIG. 18, the timing is adjusted by propagating the second pulsed light through the optical delayer 1017.

The light irradiated to the measurement target 1016 by the irradiation unit 2002 passes through the measurement target 1016 and is detected by the detection unit 2003.

The detection unit 2003 includes a light receiving objective lens 1018, a wavelength filter 1019, a photodetector 1020, and a lock-in amplifier detector 1021.

The light transmitted through the measurement target 1016 is collected by the light receiving objective lens 1018. Then, of the light collected by the light receiving objective lens 1018, only the first pulsed light having a center wavelength of 800 nm is transmitted by the wavelength filter 1019. The first pulsed light transmitted in this way is detected by the photodetector 1020. The photodetector 1020 includes a light receiving element as a light receiving unit that receives the first pulsed light and outputs an electric signal corresponding to the intensity thereof. In the electric signal output from the photodetector 1020, only the frequency component of 40 MHz is extracted by the lock-in amplifier detector 1021 to obtain amplitude information.

A two-dimensional image can be obtained by constructing an image by the PC 1022 using the coordinate information and the amplitude information of the XY scanning mirror 1014.

Here, when the frequency difference between the second pulse light and the first pulse light matches the Raman frequency of the substance in the measurement target 1016, the energy from the second pulse light to the first pulse light is generated by the Raman effect. SRS occurs in which. Therefore, since the amplitude information changes depending on the wavelength of the second pulsed light and the substance being measured, it is possible to identify and perform imaging by changing the center wavelength of the second pulsed light. It becomes. This is called SRS imaging. According to this embodiment, SRS imaging can be realized.

In the present embodiment, the subject is irradiated with two pulsed lights, and at least one of the light reflected by the subject, the light transmitted through the subject, and the light emitted by the subject is detected. As an information acquisition device for acquiring information on the subject, an SRS microscope has been described as an example. However, the present invention is not limited to this, and the information acquisition device for obtaining various spectral information such as a CARS microscope, a fluorescence microscope, and an endoscope also has any one of the first to 27th embodiments as in the present embodiment. Light source device can be used. Using the light source device according to the first to 27th embodiments as the light source unit, the subject is irradiated with two pulsed lights, the light reflected by the subject, the light transmitted through the subject, and the subject. An information acquisition device that detects at least one of the lights emitted in the light source can be configured.

[29th Embodiment]
The information acquisition device according to the 29th embodiment of the present invention will be described with reference to FIG. FIG. 19 is a diagram illustrating an information acquisition device according to the 29th embodiment.

The information acquisition device according to the 29th embodiment is an SRS microscope, and has substantially the same configuration as the information acquisition device according to the 28th embodiment. However, as shown in FIG. 19, in the information acquisition device 3000 according to the 29th embodiment, the OPO 1032 according to the second embodiment is used in place of the OPO 1012 according to the twelfth embodiment. The OPO 1032 according to the second embodiment is provided between the Yb-doped optical fiber amplifier 1009 and the optical delayer 1017.

The seed light source 1001 is a Yb fiber laser and outputs output light having a center wavelength of 1030 nm, a spectrum width of 8 nm, an output of 10 mW, and a repetition frequency of 40 MHz.

The output light from the seed light source 1001 propagates through the Yb-doped optical fiber amplifier 1002, and the spectral width is widened to 30 nm. Further, the output of the output light is 150 mW by the Yb-doped optical fiber amplifier 1002.

The output light of the Yb-doped optical fiber amplifier 1002 propagates through the fused polarization-holding photonic crystal fiber 1003 (LMA-PM-5, NKT Photonics) having a length of 3 m, and the wavelength band is extended to 1010 nm to 1080 nm. The output light then propagates through the isolator 1004 and is split in two by the optical fiber coupler 1005.

The first pulsed light, which is one of the lights branched by the optical fiber coupler 1005, has a center wavelength of 1030 nm through the wavelength filter 1006 and the Yb-doped optical fiber amplifier 1007. Similar to the 28th embodiment, the first pulsed light is branched by an optical fiber coupler using a repetition frequency multiplier 1010, and one of them is shifted by half a cycle and recombined to have a repetition frequency of 80 MHz. It becomes a light train. The output light of the repetition frequency multiplier 1010 is input to the Yb-doped optical fiber amplifier 1011 and amplified. In this way, the output light of the Yb-doped optical fiber amplifier 1011 is obtained as the first pulsed light having a center wavelength of 1030 nm.

On the other hand, the second pulsed light, which is another of the light branched by the optical fiber coupler 1005, has a variable characteristic with a center wavelength of 1020 nm to 1080 nm through the wavelength variable filter 1008 and the Yb-doped optical fiber amplifier 1009. Then, the light amplified by the Yb-doped optical fiber amplifier 1009 is input to the OPO 1032 according to the second embodiment. In this way, the OPO 1032 obtains output light having a center wavelength of 665 nm to 775 nm as the second pulsed light.

The second pulsed light having a wavelength variable characteristic of a central wavelength of 665 nm to 775 nm and the first pulsed light having a central wavelength of 1030 nm are combined by the dichroic mirror 1013 and output from the light source unit 2001. The light output from the light source unit 2001 is input to the irradiation unit 2002. At this time, the optical delayer 1017 is controlled so that the first pulsed light and the second pulsed light overlap in time in the measurement target 1016.

The irradiation direction of the first pulsed light and the second pulsed light input from the light source unit 2001 to the irradiation unit 2002 is controlled by the XY scanning mirror 1014, and the measurement target 1016 is irradiated through the irradiation objective lens 1015. To. At least one of the first pulsed light and the second pulsed light propagates through the optical delayer to adjust the timing so that they are superposed in time. For example, in the configuration shown in FIG. 19, the timing is adjusted by propagating the second pulsed light through the optical delayer 1017.

The light irradiated to the measurement target 1016 by the irradiation unit 2002 passes through the measurement target 1016 and is detected by the detection unit 2003.

The light transmitted through the measurement target 1016 is collected by the light receiving objective lens 1018. Then, of the light collected by the light receiving objective lens 1018, only the first pulsed light having a central wavelength of 1030 nm is transmitted by the wavelength filter 1019. The first pulsed light transmitted in this way is detected by the photodetector 1020 as in the 28th embodiment. In the electric signal output from the photodetector 1020, only the frequency component of 40 MHz is extracted by the lock-in amplifier detector 1021 to obtain amplitude information.

A two-dimensional image can be obtained by constructing an image by the PC 1022 using the 1014 coordinate information and the amplitude information of the XY scanning mirror.

In this way, SRS imaging can be realized by this embodiment as well as the 28th embodiment. According to the present embodiment, it is possible to realize SRS imaging capable of identifying a substance having a larger frequency difference as compared with the 28th embodiment.

In this embodiment as well, the subject is irradiated with two pulsed lights, and at least one of the light reflected by the subject, the light transmitted through the subject, and the light emitted by the subject is detected. As an information acquisition device for acquiring information on the subject, an SRS microscope has been described as an example. However, the present invention is not limited to this, and the first to 27th embodiments are carried out in the same manner as in the present embodiment for information acquisition devices such as CARS microscopes, fluorescence microscopes, multiphoton microscopes, and endoscopes that obtain various spectral information. Any light source device of any form can be used. Using the light source device according to the first to 27th embodiments as the light source unit, the subject is irradiated with two pulsed lights, the light reflected by the subject, the light transmitted through the subject, and the subject. An information acquisition device that detects at least one of the lights emitted in the light source can be configured. Further, the Yb-doped optical fiber amplifier used in the present embodiment does not have to be a Yb-doped optical fiber amplifier, and an optical amplifier using a semiconductor may be used.

[Modification Embodiment]
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, it may be modified by arbitrarily combining the configurations described as the first embodiment to the 29th embodiment described above.

Further, in the above embodiment, the case where the nonlinear optical waveguide which is a polarization-retaining photonic crystal fiber is used as the parametric gain medium has been described as an example, but the parametric gain medium is not limited to this. Various parametric gain media can be used.

Further, in the above embodiment, the case where the signal pulse light is used as the light having a wavelength different from the pump pulse light has been described as an example, but the idler light can also be used as the light having a wavelength different from the pump pulse light.

101: Pump pulse light source 102: Optical combiner 103: Parametric gain medium 201: Pump pulse light source 202: Modelock fiber laser 203: Optical fiber amplifier 204: Highly nonlinear optical fiber 205: Wavelength filter 206: Optical fiber amplifier 207: Optical combiner 208: Non-linear optical waveguide 209: Signal pulse light source 401: Optical separator 402: Optical take-out device 404: Optical delayer 501, 501-1, 501-2: Polarization rotation mechanism 502: Optical take-out device 601: Intensity modulator

Claims (27)

The first light source that outputs the first light and
A second light source that outputs a second light having a wavelength different from that of the first light,
An optical combining section that combines the first light and the second light,
The first light and the second light combined by the optical wave combination unit are input, energy is transferred from the first light to the second light by an optical parametric effect , and the first light A non-linear optical waveguide in which the group velocity of the second light matches the group velocity of the second light .
The nonlinear optical waveguide has at least two or more propagation axes with different propagation constants.
A light source device characterized in that the first light and the second light propagate on the propagation axes having different propagation constants. The light source device according to claim 1, wherein the nonlinear optical waveguide has a polarization holding characteristic. The light source device according to claim 1 or 2, wherein the optical combiner is a polarized beam combiner. The light source device according to claim 1 or 2, wherein the optical junction is a wavelength division multiplexing coupler. In the light source device according to claim 2, the nonlinear optical waveguide has a Slow axis and a Fast axis as the propagation axes having different propagation constants.
A light source device characterized in that the first light propagates on the Slow axis of the nonlinear optical waveguide, and the second light propagates on the Fast axis of the nonlinear optical waveguide. In the light source device according to claim 2, the nonlinear optical waveguide has a Slow axis and a Fast axis as the propagation axes having different propagation constants.
A light source device characterized in that the first light propagates on the Fast axis of the nonlinear optical waveguide, and the second light propagates on the Slow axis of the nonlinear optical waveguide. A light source that outputs the first light,
The first input end to which the first light is input and the second input end to which the second light having a wavelength different from that of the first light is input are combined with the first input terminal. An optical combiner having light and an output end from which the second light is output,
The light output from the output end of the optical wave portion is input, and the second light is generated from the first light by the optical parametric effect, and the group velocity of the first light and the second light are generated. a nonlinear optical waveguide and group velocity that matches the,
It has an optical extraction unit that extracts a part of the second light generated by the nonlinear optical waveguide.
A part of the second light that was not extracted by the light extraction unit is input to the second input end of the optical combiner unit, and is input to the second input terminal.
The nonlinear optical waveguide has at least two or more propagation axes with different propagation constants.
A light source device characterized in that the first light and the second light propagate on propagation axes having different propagation constants. The light source device according to claim 7, wherein the nonlinear optical waveguide has a polarization holding characteristic. The light source device according to claim 7 or 8, wherein the optical combiner is a polarized beam combiner. The light source device according to claim 7 or 8, wherein the optical junction is a wavelength division multiplexing coupler. In the light source device according to claim 8, the nonlinear optical waveguide has a Slow axis and a Fast axis as the propagation axes having different propagation constants, and the first light propagates through the Slow axis of the nonlinear optical waveguide. A light source device, characterized in that the second light propagates along the Fast axis of the nonlinear optical waveguide. In the light source device according to claim 8, the nonlinear optical waveguide has a Slow axis and a Fast axis as the propagation axes having different propagation constants, and the first light propagates through the Fast axis of the nonlinear optical waveguide. A light source device, characterized in that the second light propagates along the Slow axis of the nonlinear optical waveguide. In the light source device according to any one of claims 7 to 12, the second light is provided between the light extraction unit and the optical merging unit to delay the second light and synchronize it with the first light. A light source device characterized by having an optical delayer. The light source device according to any one of claims 1 to 13, further comprising a polarization beam splitter that separates the first light from the light output from the nonlinear optical waveguide. The light source device according to any one of claims 1 to 13, further comprising a wavelength division multiplexing coupler that separates the first light from the light output from the nonlinear optical waveguide. In the light source device according to any one of claims 1 to 15, the optical merging unit has a first input terminal into which the first light is input and a second input terminal into which the second light is input. Has an input end and
Light provided immediately before at least one of the first input end and the second input end of the optical wave portion and input to one of the first input end and at least one of the second input ends. A light source device characterized by having a polarized light rotating unit that rotates the polarized light of. In the light source device according to any one of claims 1 to 15, the first light and the second light provided between the optical junction and the non-linear optical waveguide and input to the non-linear optical waveguide. A light source device having a polarized light rotating portion for rotating the polarized light of the light. The light source device according to claim 16 or 17, wherein the optical junction is a wavelength division multiplexing coupler. The light source device according to any one of claims 1 to 18 , further comprising an intensity adjusting unit for adjusting the peak intensity of the first light. The light source device according to claim 19 , wherein the intensity adjusting unit is a variable intensity modulator. The light source device according to claim 19 , wherein the intensity adjusting unit is a chirp adjusting mechanism for adjusting the chirp amount of the first light. The light source device according to claim 19 , wherein the intensity adjusting unit is an optical amplifier that amplifies the first light, and is an optical amplifier having a variable amplification factor. The light source device according to any one of claims 1 to 2 2, wherein the first light source, the light source and wherein the wavelength of the first light is a wavelength tunable light source is variable. The light source device according to any one of claims 1 to 2 3, the first light is a pulse light source device that satisfy the following equation.

(However, in the above formulas, gamma is the nonlinear coefficient of the nonlinear optical waveguide, T _FWHM is the first optical pulse time width, the E _p of the first optical pulse energy, beta ₂ is the nonlinear optical waveguide It is a quadratic dispersion.) The light source device according to any one of claims 1 to 2 4, wherein the wavelength of the second light source and wherein the said is shorter than the first light. The light source device according to any one of claims 1 to 2 4, wherein the wavelength of the second light source and wherein the than the first light is a longer wavelength. The subject is irradiated with two pulsed lights having different center wavelengths, and at least one of the light reflected by the subject, the light transmitted through the subject, and the light emitted by the subject is detected. An information acquisition device that acquires information on the subject.
A light source unit that emits two pulsed lights with different center wavelengths,
A light receiving unit that receives at least one of light reflected by the subject, light transmitted through the subject, and light emitted by the subject.
Have,
The information acquisition device according to claim 1, wherein the light source unit includes the light source device according to any one of claims 1 to 26 , which outputs at least one of two pulsed lights having different center wavelengths.

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