CN118198839A - Double-end output dual-wavelength optical fiber laser - Google Patents
Double-end output dual-wavelength optical fiber laser Download PDFInfo
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- 239000013307 optical fiber Substances 0.000 title claims description 14
- 239000000835 fiber Substances 0.000 claims abstract description 287
- 238000001069 Raman spectroscopy Methods 0.000 claims abstract description 92
- 238000005086 pumping Methods 0.000 claims abstract description 37
- 230000009977 dual effect Effects 0.000 claims description 11
- 230000003287 optical effect Effects 0.000 claims description 10
- 239000004065 semiconductor Substances 0.000 claims description 6
- 229910052769 Ytterbium Inorganic materials 0.000 claims description 2
- NAWDYIZEMPQZHO-UHFFFAOYSA-N ytterbium Chemical group [Yb] NAWDYIZEMPQZHO-UHFFFAOYSA-N 0.000 claims description 2
- 230000000694 effects Effects 0.000 description 7
- 238000001228 spectrum Methods 0.000 description 7
- 239000010453 quartz Substances 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
- H01S3/0675—Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094042—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a fibre laser
- H01S3/094046—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a fibre laser of a Raman fibre laser
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/106—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity
- H01S3/108—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering
- H01S3/1086—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering using scattering effects, e.g. Raman or Brillouin effect
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Abstract
The invention provides a double-end output dual-wavelength fiber laser, which comprises a high reflection fiber grating, a gain fiber, a low reflection fiber grating, a backward pumping beam combiner, a pumping source, a Raman high reflection fiber grating, a forward output end and a backward output end, wherein the pumping fiber of the backward pumping beam combiner is connected with the pumping source, and the high reflection fiber grating, the gain fiber and the low reflection fiber grating are sequentially connected to form a fiber laser resonant cavity; the Raman high-reflection fiber grating is positioned outside the fiber laser resonant cavity; the Raman high-reflection fiber grating is connected between the low-reflection fiber grating and the backward pumping beam combiner or between the backward pumping beam combiner and the forward output end. The invention utilizes the Raman high-reflection fiber grating to output Stokes light from the backward output end, and the signal light output by the fiber laser resonant cavity is output from the forward output end, thereby realizing double-end output of dual-wavelength laser.
Description
Technical Field
The invention mainly relates to the technical field of fiber lasers, in particular to a double-end output dual-wavelength fiber laser.
Background
The fiber laser has the advantages of high efficiency, compact structure, flexible operation, low maintenance cost and the like, and gradually becomes a main light source in the fields of industrial manufacture, energy environment, biological medical treatment, national defense safety and the like. Fiber lasers are widely used in various fields, and how to reduce the cost, volume and weight of fiber lasers is one of the important research points of fiber lasers. The conventional near-single-mode fiber laser generally adopts a resonant cavity mode, a resonant cavity is formed by a high-reflection grating and a low-reflection grating, and laser is output by the low-reflection fiber grating.
For all-fiber lasers with dual output. The basic idea of the existing scheme is as follows: the low-reflection fiber grating is used for replacing the high-reflection fiber grating in the common resonant cavity, and laser output is realized at two ends of the laser. Therefore, the functions of the two lasers can be realized by only one set of water cooling structure, one resonant cavity and one gain fiber, and the cost of the lasers is greatly reduced under the condition of equal output power and beam quality. However, the center wavelengths of the two gratings in the oscillator of the scheme structure must be identical, and the wavelengths of the laser light output from the two ends are identical.
On the other hand, when the fiber laser oscillator operates at high power, nonlinear effect can be generated through the action of the long fiber, and once the stimulated Raman scattering threshold is reached, energy transfer can be generated on the signal laser, so that stimulated Raman laser is generated, and the spectral purity and the beam quality of the strong output laser are affected. At present, a common method for inhibiting the stimulated raman scattering effect is to filter raman laser through a filter device such as a chirped inclined fiber bragg grating. The disadvantages of this approach are increased cost, reduced efficiency of the laser, and limited power tolerance of the filter device.
Disclosure of Invention
Aiming at the cost control requirement of the fiber laser and the stimulated Raman scattering problem faced by the existing high-power fiber oscillator, the invention provides a double-end output dual-wavelength fiber laser, which aims to remove the influence of the stimulated Raman scattering effect, purify the spectrum of forward output laser, and simultaneously output Stokes light generated by the stimulated Raman scattering effect from the backward direction, so that the fiber oscillator realizes double-end output of dual-wavelength laser.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
In one aspect, the invention provides a dual-end output dual-wavelength fiber laser, which comprises a high reflection fiber grating, a gain fiber, a low reflection fiber grating, a backward pumping beam combiner, a pumping source, a Raman high reflection fiber grating, a forward output end and a backward output end, wherein the pumping fiber of the backward pumping beam combiner is connected with the pumping source, and the high reflection fiber grating, the gain fiber and the low reflection fiber grating are sequentially connected to form a fiber laser resonant cavity; the Raman high-reflection fiber grating is positioned outside the fiber laser resonant cavity; the Raman high-reflection fiber grating is connected between the low-reflection fiber grating and the backward pumping beam combiner or between the backward pumping beam combiner and the forward output end, the center wavelength of the Raman high-reflection fiber grating is shifted down by 13.2THz compared with the center wavelength of the low-reflection fiber grating, the bandwidth of the Raman high-reflection fiber grating is in a range of 10nm to 40nm, and the bandwidth of the Raman high-reflection fiber grating and the bandwidth of the high-reflection fiber grating do not overlap.
As a further improvement of the above technical scheme:
further, the type of the pump source is not limited, and may be a semiconductor laser, a fiber laser, or other types of lasers. The wavelength of the pump source is not limited, and a semiconductor laser having a wavelength of 976nm, 915nm, 940nm or 981nm may be used, or the pump source may be a fiber laser having a wavelength of 1018 nm.
Further, the backward pump beam combiner is an (n+1) ×1 pump signal beam combiner.
Further, the device also comprises a forward pump beam combiner, and adopts a structure of bidirectional pumping, wherein the forward pump beam combiner is an (n+1) x1 pump signal beam combiner.
Further, the center wavelength of the high-reflection fiber grating is the same as that of the low-reflection fiber grating. Or the difference of the center wavelength of the high-reflection fiber grating and the low-reflection fiber grating is within 0.4 nm.
Further, the gain fiber length is determined by pump absorption and is typically varied from a few meters to tens of meters.
Further, the type of the gain fiber is not limited to the step-index distribution fiber, but may be another fiber having a different refractive index distribution, such as a graded-index fiber, a partially doped fiber, a W-type fiber, etc.
Compared with the prior art, the invention can produce the following technical effects:
The double-end output dual-wavelength fiber laser provided by the invention does not need to overcome the stimulated Raman scattering effect in the high-power fiber oscillator, and can be utilized to enable the signal laser and the Stokes wavelength laser to be respectively output from two ends of the laser. When the fiber laser oscillator operates at high power and reaches the stimulated raman scattering threshold, stokes light with bidirectional transmission is generated, and the wavelength frequency shift is about 13.2 THz. And the center wavelength of the Raman high-reflection grating is Stokes wavelength, the center wavelength of the Raman high-reflection fiber grating is shifted down by 13.2THz compared with the center wavelength of the low-reflection fiber grating, and the Raman high-reflection fiber grating has no region overlapping with the bandwidth of the high-reflection fiber grating. Therefore, the signal wavelength output by the laser oscillator can be output from the front-facing output end through the Raman high-reflection fiber grating without loss, meanwhile, the Raman high-reflection fiber grating can reflect forward transmitted Stokes light to the rear-facing direction, and Stokes light can also be output from the rear-facing output end through the fiber laser resonant cavity without loss, so that double-end output of the dual-wavelength laser is realized.
The double-end output double-wavelength fiber laser provided by the invention can generate laser with two wavelengths simultaneously without additional design, and reduces the number of pumping sources. The dual-wavelength laser can synthesize a beam of laser with higher brightness by utilizing the existing incoherent synthesis technology/spectrum synthesis, so that the laser output power is improved, the laser conversion efficiency can be improved, and the cost of the high-power fiber laser is greatly reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a dual-end output dual-wavelength fiber laser according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a dual-end output dual-wavelength fiber laser according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a dual-end output dual-wavelength fiber laser according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a dual-end output dual-wavelength fiber laser according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a dual-end output dual-wavelength fiber laser according to an embodiment of the present invention;
Reference numerals in the drawings:
1. A high reflection fiber grating; 2. a gain fiber; 3. a low reflection fiber grating; 4. a backward pumping combiner; 5. a pump source; 6. a raman high reflection fiber grating; 7. a forward output; 8. a backward output end; 9. a forward pump combiner; 10. an amplifying stage optical path.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, an embodiment provides a dual-end output dual-wavelength fiber laser, which includes a high reflection fiber grating 1, a gain fiber 2, a low reflection fiber grating 3, a backward pump beam combiner 4, a pump source 5, a raman high reflection fiber grating 6, a forward output end 7 and a backward output end 8, wherein the pump fiber of the backward pump beam combiner 4 is connected with the pump source 5, and the high reflection fiber grating 1, the gain fiber 2 and the low reflection fiber grating 3 are sequentially connected to form a fiber laser resonant cavity; the Raman high-reflection fiber bragg grating 6 is positioned outside the fiber laser resonant cavity; the Raman high-reflection fiber grating 6 is connected between the backward pumping beam combiner 4 and the forward output end 7, and the high-reflection fiber grating 1 is connected with the backward output end 8. The forward output end 7 and the backward output end 8 are both fiber end caps. The center wavelength of the raman high reflection fiber grating 6 is shifted down by 13.2THz compared with the center wavelength of the low reflection fiber grating 3, the bandwidth of the raman high reflection fiber grating 3 is in the range of 10nm to 40nm, and the bandwidth of the raman high reflection fiber grating 6 and the bandwidth of the high reflection fiber grating 1 have no overlapping area.
Referring to fig. 2, an embodiment provides a dual-end output dual-wavelength fiber laser, which includes a high reflection fiber grating 1, a gain fiber 2, a low reflection fiber grating 3, a backward pump beam combiner 4, a pump source 5, a raman high reflection fiber grating 6, a forward output end 7 and a backward output end 8, wherein the pump fiber of the backward pump beam combiner 4 is connected with the pump source 5, and the high reflection fiber grating 1, the gain fiber 2 and the low reflection fiber grating 3 are sequentially connected to form a fiber laser resonant cavity; the Raman high-reflection fiber bragg grating 6 is positioned outside the fiber laser resonant cavity; the Raman high-reflection fiber grating 6 is connected between the low-reflection fiber grating 3 and the backward pumping beam combiner 4, and the high-reflection fiber grating 1 is connected with a backward output end 8. The forward output end 7 and the backward output end 8 are both fiber end caps. Wherein, the high reflection fiber grating 6 of Raman adopts the chirped Bragg grating, according to the Raman gain spectrum of the quartz fiber, the center wavelength of the high reflection fiber grating 6 of Raman should be 13.2THz down compared with the center wavelength of the low reflection fiber grating 3. The bandwidth of the raman highly reflective fiber grating 3 can be in the range of 10nm to 40nm according to the power and spectral characteristics of laser output, and the bandwidth of the raman highly reflective fiber grating 6 and the bandwidth of the highly reflective fiber grating 1 do not overlap.
Referring to fig. 3, an embodiment provides a dual-end output dual-wavelength fiber laser, which includes a forward pump combiner 9, a high reflection fiber grating 1, a gain fiber 2, a low reflection fiber grating 3, a backward pump combiner 4, a pump source 5, a raman high reflection fiber grating 6, a forward output end 7, and a backward output end 8. The pump fiber of the backward pump beam combiner 4 is connected with a pump source 5, and the high-reflection fiber grating 1, the gain fiber 2 and the low-reflection fiber grating 3 are sequentially connected to form a fiber laser resonant cavity; the Raman high-reflection fiber bragg grating 6 is positioned outside the fiber laser resonant cavity; the Raman high-reflection fiber grating 6 is connected between the backward pumping beam combiner 4 and the forward output end 7. The pump fiber of the forward pump beam combiner 9 is connected with the pump source 5, the signal fiber on one side of the forward pump beam combiner 9 is connected with the high reflection fiber grating 1, and the signal fiber on the other side of the forward pump beam combiner 9 is connected with the backward output end 8. The forward output end 7 and the backward output end 8 are both fiber end caps. The center wavelength of the raman high reflection fiber grating 6 is shifted down by 13.2THz compared with the center wavelength of the low reflection fiber grating 3, the bandwidth of the raman high reflection fiber grating 3 is in the range of 10nm to 40nm, and the bandwidth of the raman high reflection fiber grating 6 and the bandwidth of the high reflection fiber grating 1 have no overlapping area.
Referring to fig. 4, an embodiment provides a dual-end output dual-wavelength fiber laser, which includes a forward pump combiner 9, a high reflection fiber grating 1, a gain fiber 2, a low reflection fiber grating 3, a backward pump combiner 4, a pump source 5, a raman high reflection fiber grating 6, a forward output end 7, and a backward output end 8. The pump fiber of the backward pump beam combiner 4 is connected with a pump source 5, and the high-reflection fiber grating 1, the gain fiber 2 and the low-reflection fiber grating 3 are sequentially connected to form a fiber laser resonant cavity; the Raman high-reflection fiber bragg grating 6 is positioned outside the fiber laser resonant cavity; the Raman high-reflection fiber grating 6 is connected between the low-reflection fiber grating 3 and the backward pumping beam combiner 4. The pump fiber of the forward pump beam combiner 9 is connected with the pump source 5, the signal fiber on one side of the forward pump beam combiner 9 is connected with the high reflection fiber grating 1, and the signal fiber on the other side of the forward pump beam combiner 9 is connected with the backward output end 8. The forward output end 7 and the backward output end 8 are both fiber end caps. Wherein, the high reflection fiber grating 6 of Raman adopts the chirped Bragg grating, according to the Raman gain spectrum of the quartz fiber, the center wavelength of the high reflection fiber grating 6 of Raman should be 13.2THz down compared with the center wavelength of the low reflection fiber grating 3. The bandwidth of the raman highly reflective fiber grating 3 can be in the range of 10nm to 40nm according to the power and spectral characteristics of laser output, and the bandwidth of the raman highly reflective fiber grating 6 and the bandwidth of the highly reflective fiber grating 1 do not overlap.
Referring to fig. 5, an embodiment provides a dual-end output dual-wavelength fiber laser, which includes a backward output end 8, an amplifying stage optical path 10, a forward pump beam combiner 9, a high reflection fiber grating 1, a gain fiber 2, a low reflection fiber grating 3, a backward pump beam combiner 4, a raman high reflection fiber grating 6, and a forward output end 7, which are sequentially connected. The pump fiber of the backward pump beam combiner 4 is connected with a pump source 5, and the high-reflection fiber grating 1, the gain fiber 2 and the low-reflection fiber grating 3 are sequentially connected to form a fiber laser resonant cavity; the Raman high-reflection fiber grating 6 is positioned outside the fiber laser resonant cavity. The Raman high-reflection fiber grating 6 is connected between the backward pumping beam combiner 4 and the forward output end 7. The pump fiber of the forward pump beam combiner 9 is connected with a pump source 5, the signal fiber on one side of the forward pump beam combiner 9 is connected with a high reflection fiber grating 1, the signal fiber on the other side of the forward pump beam combiner 9 is connected with one end of an amplifying stage optical path 10, the amplifying stage optical path 10 comprises more than one amplifying stage, and each amplifying stage comprises a gain fiber for realizing power amplification. The other end of the amplifying stage optical path 10 is connected with the backward output end 8. The forward output end 7 and the backward output end 8 are both fiber end caps. The gain fiber of the amplifying stage optical path 10 may be a quartz fiber or a doped fiber. Wherein, the high reflection fiber grating 6 of Raman adopts the chirped Bragg grating, according to the Raman gain spectrum of the quartz fiber, the center wavelength of the high reflection fiber grating 6 of Raman should be 13.2THz down compared with the center wavelength of the low reflection fiber grating 3. The bandwidth of the raman highly reflective fiber grating 3 can be in the range of 10nm to 40nm according to the power and spectral characteristics of laser output, and the bandwidth of the raman highly reflective fiber grating 6 and the bandwidth of the highly reflective fiber grating 1 do not overlap.
The stimulated raman scattering effect in a fiber laser is undesirable and the stimulated raman scattering threshold will be greatly reduced when the bandwidth of the low reflection fiber grating 3 is narrower. When the threshold value of stimulated Raman scattering is reached, the energy of the signal light is transferred to the Raman stokes light, and when laser is output, the Raman stokes light transmitted in the forward direction is changed into the Raman stokes light transmitted in the backward direction through reflection of the Raman high reflection grating, the signal light is only output in the forward direction, the fiber bragg grating of the resonant cavity has no loss on Raman wavelength, and the Raman light is output in the backward direction. When the stokes optical power is weak, the structure provided in the embodiment of fig. 5 may be adopted, and the gain optical fiber may be a quartz optical fiber or a doped optical fiber after one-stage amplification or multi-stage amplification. The method can regulate and control the output power at two ends of the laser, and increase the spectrum synthesis efficiency.
In any of the foregoing embodiments, the backward pump combiner 4 is an n+1x1 pump signal combiner, and includes N pump fibers, where each pump fiber of the backward pump combiner 4 is connected to one pump source 5.
In the above embodiment, for example, in the embodiment that adopts bidirectional pumping, that is, includes the forward pump combiner 9, the forward pump combiner 9 is an n+1x1 pump signal combiner, including N pump fibers, and each pump fiber of the forward pump combiner 9 is connected to one pump source 5.
In any of the foregoing embodiments, the type of the pump source is not limited, and may be a semiconductor laser or a fiber laser.
In any of the above embodiments, the length of the gain fiber in the fiber laser resonator is determined according to the pump absorption, and is typically several meters to several tens of meters.
In any of the above embodiments, the wavelength of the pump source is not limited, and the pump source is a semiconductor laser with a wavelength of 976nm, 915nm, 940nm or 981nm, so that the gain fiber in the fiber laser resonator is a tens of meters ytterbium-doped fiber. Or the pumping source adopts an optical fiber laser with the wavelength of 1018nm, and the gain optical fiber in the optical fiber laser resonant cavity is an ytterbium-doped optical fiber with the wavelength of tens of meters.
Further, the type of the gain fiber in the fiber laser resonator is not limited to the step-index distributed fiber, and may be other refractive index distributed fibers, such as graded-index fiber, partially doped fiber, W-type fiber, etc.
In any of the above embodiments, the center wavelengths of the high reflection fiber grating and the low reflection fiber grating are the same. Or the difference of the center wavelength of the high-reflection fiber grating and the low-reflection fiber grating is within 0.4 nm.
In any of the foregoing embodiments, the gain fiber in the fiber laser resonator is an ytterbium doped fiber or other type of doped fiber.
The key of any embodiment of the invention is that a Raman high reflection grating is introduced into the fiber laser oscillator, forward transmitted Stokes light in the fiber laser resonant cavity is output from the backward direction of the oscillator, and the Raman Stokes light can not influence the resonant cavity in the backward transmission process. The center wavelength of the forward signal laser is determined by the grating pair center wavelength of the resonant cavity, and the frequency shift when the gain coefficient is maximum is about 13.2THz according to the Raman gain spectrum of the quartz fiber. For example, in an ytterbium-doped fiber laser with a signal laser wavelength of 1080nm, the raman wavelength is about 1133nm, and the grating bandwidth of the resonator is typically below 4nm, so that the resonator does not have a loss or other effect on the transmission of raman stokes light. On the other hand, when stimulated raman scattering is generated by the optical fiber oscillator, the raman stokes light is transmitted in two directions, which means that the backward transmitted raman stokes light does not influence the operation of the resonant cavity.
The embodiment shown in fig. 1 or fig. 2 is adopted to provide a double-end output dual-wavelength fiber laser, a backward pumping structure is adopted, the backward raman optical power borne by the high-reflection fiber grating 1 is higher, and the preparation process of femtosecond laser inscribing the grating can be adopted to improve the grating power bearing capacity.
When the dual-end output dual-wavelength optical fiber laser provided by the embodiment shown in fig. 3 or fig. 4 is adopted and a bidirectional pumping structure is adopted, the forward pumping signal beam combiner bears higher raman optical power, and in order to prevent the raman light of the signal fiber of the beam combiner from leaking to the pumping fiber to affect the pumping source, the anti-reflection capability of the pumping source should be considered.
By adopting the dual-end output dual-wavelength fiber laser provided by the embodiment shown in fig. 5, even if the stimulated raman effect of the original oscillator is weak or the power of the back raman light reflected to the original oscillator is low, the power of the back raman light can be improved by amplification, the back output raman light of the fiber oscillator in the process is equivalent to a seed signal, the resonance cavity is not influenced, and the stability and the reliability of the system are greatly enhanced.
The invention is not a matter of the known technology.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The double-end output dual-wavelength fiber laser is characterized by comprising a high-reflection fiber grating (1), a gain fiber (2), a low-reflection fiber grating (3), a backward pumping beam combiner (4), a pumping source (5), a Raman high-reflection fiber grating (6), a forward output end (7) and a backward output end (8), wherein the pumping fiber of the backward pumping beam combiner (4) is connected with the pumping source (5), and the high-reflection fiber grating (1), the gain fiber (2) and the low-reflection fiber grating (3) are sequentially connected to form a fiber laser resonant cavity; the Raman high-reflection fiber bragg grating (6) is positioned outside the fiber laser resonant cavity; the Raman high-reflection fiber grating (6) is connected between the low-reflection fiber grating (3) and the backward pumping beam combiner (4) or the Raman high-reflection fiber grating (6) is connected between the backward pumping beam combiner (4) and the forward output end (7), wherein the center wavelength of the Raman high-reflection fiber grating is shifted down by 13.2THz compared with the center wavelength of the low-reflection fiber grating, the bandwidth of the Raman high-reflection fiber grating is in a range of 10nm to 40nm, and the bandwidth of the Raman high-reflection fiber grating and the bandwidth of the high-reflection fiber grating do not overlap.
2. The dual-end-output dual-wavelength fiber laser according to claim 1, characterized in that the highly reflective fiber grating (1) is connected to the backward output (8).
3. The dual-end output dual-wavelength optical fiber laser according to claim 1 or 2, further comprising a forward pump combiner (9), wherein a pump source (5) is connected to a pump fiber of the forward pump combiner (9), a signal fiber on one side of the forward pump combiner (9) is connected to the high reflection fiber grating (1), and a signal fiber on the other side of the forward pump combiner (9) is connected to the backward output end (8).
4. A dual-end output dual-wavelength optical fiber laser according to claim 3, characterized in that the forward pump combiner (9) is an (n+1) ×1 pump signal combiner, comprising N pump fibers, and each pump fiber of the forward pump combiner (9) is connected to a pump source (5).
5. The dual-end output dual-wavelength optical fiber laser according to claim 2, wherein the backward pump combiner (4) is an (n+1) ×1 pump signal combiner, and comprises N pump fibers, and each pump fiber of the backward pump combiner (4) is connected with a pump source (5).
6. The dual end output dual wavelength fiber laser of claim 1 or 2 or 4 or 5, wherein the pump source is a semiconductor laser or a fiber laser.
7. The dual output dual wavelength fiber laser of claim 6, wherein the center wavelengths of the high and low reflection fiber gratings are the same or within 0.4 nm.
8. The dual end output dual wavelength fiber laser of claim 1, wherein the gain fiber is an ytterbium doped fiber.
9. The dual end output dual wavelength fiber laser of claim 1, wherein the pump source is a semiconductor laser having a wavelength of 976nm, 915nm, 940nm or 981nm, or the pump source is a fiber laser having a wavelength of 1018 nm.
10. The dual output dual wavelength fiber laser of claim 1, wherein the backward output is coupled to an amplifying stage optical path.
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