JP4378936B2 - Semiconductor laser - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor laser whose oscillation wavelength is variable.
[0002]
[Prior art]
As this type of semiconductor laser, there is a semiconductor laser having a non-uniform diffraction grating (see Non-Patent Document 1). Such a semiconductor laser includes an active region and a pair of DBR (Distributed Bragg Reflector) reflection regions sandwiching the active region. The reflection spectrum of the pair of DBR reflection regions has a large number of reflection peaks that appear periodically. The interval between the reflection peaks is designed to be slightly different in each DBR reflection region. By adjusting the injection current and changing the refractive index of one of the DBR reflection regions, the vernier effect is shifted. Is used to vary the oscillation wavelength over a very wide range.
[0003]
[Non-Patent Document 1]
Isao Kobayashi, “Optical Integrated Device”, first edition, Kyoritsu Publishing Co., Ltd., July 1999, p106
[0004]
[Problems to be solved by the invention]
However, the conventional semiconductor laser described above has a problem that it is difficult to manufacture the semiconductor laser because it is necessary to form a diffraction grating in the semiconductor using a microfabrication technique. Further, such a semiconductor laser has low temperature stability and temperature control is essential.
[0005]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a semiconductor laser having a variable oscillation wavelength that has high temperature stability and is easy to manufacture.
[0006]
[Means for Solving the Problems]
The semiconductor laser according to the present invention includes (1) a semiconductor optical amplification device having an active region and first and second light emitting surfaces facing each other across the active region, and (2) a first light emitting surface and light. A first optical waveguide device in which a multiwavelength diffraction grating showing a plurality of reflection peaks at a first wavelength interval is formed in an optical waveguide region that is coupled and formed mainly of quartz; and (3) a second A multiwavelength diffraction grating having a plurality of reflection peaks at a second wavelength interval different from the first wavelength interval is formed in an optical waveguide region formed mainly of quartz. And (4) temperature adjusting means for adjusting the refractive index of the optical waveguide region provided in the second optical waveguide device.
[0007]
Since this semiconductor laser includes the first and second optical waveguide devices in which a multi-wavelength diffraction grating is formed, the semiconductor laser is manufactured in comparison with a conventional laser that uses a microfabrication technique to form a diffraction grating in a semiconductor. It becomes easy. In addition, since the optical waveguide region in which the multi-wavelength diffraction grating is formed in the second optical waveguide device is mainly made of quartz whose refractive index has a small temperature dependence, the refractive index is changed by changing the temperature by the temperature adjusting means. Even if it is easy to adjust and change the reflection spectrum of the multi-wavelength diffraction grating, the refractive index is stable with respect to temperature changes such as changes in environmental temperature, and a semiconductor laser with high temperature stability should be used. Can do. Furthermore, since the refractive index of the optical waveguide region is adjusted by changing the temperature by the temperature adjusting means, the oscillation wavelength and the oscillation output can be stabilized as compared with the case where the refractive index is adjusted by the injection current.
[0008]
In the semiconductor laser according to the present invention, the second optical waveguide device may be a planar optical waveguide. In this way, it becomes easy to form the temperature adjusting means on the second optical waveguide device, and as a result, the manufacture of the semiconductor laser becomes easy.
[0009]
In the semiconductor laser according to the present invention, the first and second optical waveguide devices may be planar optical waveguides, and the first and second optical waveguide devices may be provided on the same substrate. This facilitates alignment between the first and second optical waveguide devices and the semiconductor optical amplification device.
[0010]
In the semiconductor laser according to the present invention, the first optical waveguide device may be an optical fiber.
[0011]
In the semiconductor laser according to the present invention, at least one multi-wavelength diffraction grating of the first and second optical waveguide devices may include a plurality of grating portions with a predetermined period arranged at equal intervals. In this way, the wavelength that gives the reflection peak of the multi-wavelength diffraction grating is defined by the predetermined period of the grating part and the intervals of the plurality of grating parts arranged at equal intervals.
[0012]
In the semiconductor laser according to the present invention, at least one multiwavelength diffraction grating of the first and second optical waveguide devices includes a plurality of first grating portions having a first refractive index and a plurality having a second refractive index. The second grating part may be provided, and the first grating part and the second grating part may be alternately and continuously arranged. In this way, the wavelength giving the reflection peak of the multi-wavelength diffraction grating is defined by the period of the first grating part and the second grating part and the repetition period of the first grating part and the second grating part.
[0013]
In the semiconductor laser according to the present invention, at least one multiwavelength diffraction grating of the first and second optical waveguide devices may include a plurality of chirped grating portions arranged at equal intervals. In this way, the wavelength giving the reflection peak of the multi-wavelength diffraction grating is defined by the period included in the chirped grating portion and the intervals between the plurality of grating portions arranged at equal intervals.
[0014]
In the semiconductor laser according to the present invention, at least one multiwavelength diffraction grating of the first and second optical waveguide devices has a plurality of grating portions each having a different period, and each grating portion is spatially arranged. It is good also as being characterized. In this way, the wavelength giving the reflection peak of the multi-wavelength diffraction grating is defined by different periods of the plurality of grating portions. And since each grating part is arrange | positioned spatially, the length of a super period grating can be shortened. In addition, when writing the grating part of each wavelength, interference at the time of overwriting can be suppressed by applying an apodization.
[0015]
In the semiconductor laser according to the present invention, at least one of the first and second optical waveguide devices is a planar optical waveguide, and the multi-wavelength diffraction grating includes an uneven portion formed in the optical waveguide region along the optical waveguide direction. This may be a feature. In this way, it is possible to form a diffraction grating with a complicated pattern.
[0016]
In the semiconductor laser according to the present invention, the active region of the semiconductor optical amplifier device may include a spot size conversion unit. In this way, the coupling efficiency between the first and second optical waveguide devices and the semiconductor optical amplification device can be improved.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a semiconductor laser according to the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
[0018]
FIG. 1 is a perspective view showing the configuration of the semiconductor laser according to the present embodiment, and FIG. 2 is a plan view showing the configuration of the semiconductor laser shown in FIG.
[0019]
As shown in FIGS. 1 and 2, the semiconductor laser 10 includes a semiconductor optical amplifying device 12, first and second optical waveguide devices 14 and 16, and temperature adjusting means 18.
[0020]
The semiconductor optical amplifying device 12 has an active region 20 and first and second light emitting surfaces 22 and 24 facing each other with the active region 20 interposed therebetween. The active region 20 generates light when carriers are injected through an electrode (not shown). The first and second light emitting surfaces 22 and 24 include antireflection films, and light reflection at the end surfaces is reduced.
[0021]
FIG. 3 is a diagram showing a cross-sectional structure of the semiconductor optical amplification device 12 when the semiconductor laser 10 shown in FIG. 2 is cut along the line III-III. As shown in FIG. 3, the semiconductor optical amplifying device 12 has first and second light emitting surfaces 22 and 24 that face each other, and the active region 20 emits a second light emitting from the first light emitting surface 22. It extends towards the surface 24. The active region 20 has spot size converters 26 at both ends near the first and second light emitting surfaces 22 and 24. That is, as shown in FIG. 4, both end portions of the active region 20 are tapered in the horizontal direction or the vertical direction, and the thickness or width of the active region 20 is extremely narrowed. Thereby, the light propagating through the active region 20 oozes out to the outside, and the spot size of the emitted light is increased. Thereby, the coupling efficiency between the semiconductor optical amplification device 12 and the first and second optical waveguide devices 14 and 16 is improved.
[0022]
The first optical waveguide device 14 is provided as a planar optical waveguide (PLC). The first optical waveguide device 14 has an optical waveguide region 28 formed mainly of quartz. In the optical waveguide region 28, a multi-wavelength diffraction grating 30 showing a plurality of reflection peaks at the first wavelength interval is formed. The first optical waveguide device 14 is optically coupled to the first light exit surface 22 of the semiconductor optical amplification device 12.
[0023]
The second optical waveguide device 16 is provided as a planar optical waveguide (PLC). The second optical waveguide device 16 has an optical waveguide region 32 formed mainly of quartz. In the optical waveguide region 32, a multi-wavelength diffraction grating 34 is formed that shows a plurality of reflection peaks at a second wavelength interval different from the first wavelength interval. The second optical waveguide device 16 is optically coupled to the second light exit surface 24 of the semiconductor optical amplification device 12.
[0024]
The first and second optical waveguide devices 14 and 16 are provided on the same substrate. The semiconductor optical amplification device 12 is mounted on a stepped portion 36 provided between the first and second optical waveguide devices 14 and 16. As described above, since the first and second optical waveguide devices 14 and 16 are provided on the same substrate, the alignment between the first and second optical waveguide devices 14 and 16 and the semiconductor optical amplification device 12 is achieved. It becomes easy. In particular, in the present embodiment, the first and second optical waveguide devices 14 and 16 are provided with one planar optical waveguide, and the central portion is extended in the optical waveguide region so that a stepped portion 36 is generated in the central portion. It is formed by grinding in a direction orthogonal to the direction and dividing one planar optical waveguide into two planar optical waveguides. Thereby, the alignment between the first optical waveguide device 14 and the second optical waveguide device 16 becomes unnecessary, and the semiconductor optical amplifying device 12 is mounted on the step portion 36, and this is extended in the extending direction of the optical waveguide regions 28 and 32. By shifting in a direction perpendicular to the axis, positioning can be performed only by alignment in one axis direction.
[0025]
The temperature adjusting means 18 is provided immediately above the portion where the multiwavelength diffraction grating 34 is formed in the optical waveguide region 32 of the second optical waveguide device 16. The temperature adjusting means 18 adjusts the refractive index of this portion of the optical waveguide region 32. As the temperature control means 18, what is called a micro heater can be used. Such a microheater can be formed, for example, by vapor deposition or sputtering of W, Cr, TaSi, TaN or the like.
[0026]
FIG. 5 is an explanatory diagram for explaining the multi-wavelength diffraction gratings 30 and 34 provided in the optical waveguide regions 28 and 32 of the first and second optical waveguide devices 14 and 16. In FIG. 5, the optical waveguide regions 28 and 32 are taken out from the first and second optical waveguide devices 14 and 16 for illustration. As shown in FIG. 5, the multi-wavelength diffraction grating 30 and 34, the grating 38 of period lambda _a is configured it is arranged at equal intervals in the period lambda _b. The multi-wavelength diffraction gratings 30 and 34 can be formed as follows.
[0027]
First, a desired phase grating mask is placed on the side surface of the optical waveguide region of the optical waveguide device, and this mask is irradiated with ultraviolet rays having a sharp spectrum (usually using an excimer laser). Then, utilizing the interference effect of light passing through the phase grating mask, to produce a grating 38 with the intensity of the beam corresponding to the period lambda _a. This By is repeated at intervals lambda _b, multi-wavelength diffraction grating 30, 34 shown in FIG. 5 is formed.
[0028]
FIG. 6 is a diagram showing the reflection spectra of the multiwavelength diffraction gratings 30 and 34. Individual reflection peak in FIG 6 is a peak due to the periodic lambda _a. And the interval Δλ between adjacent reflection peaks is defined by the period Λ _b ,
Δλ = λ ₀ ² / 2nΛ _b
It is represented by Here, λ ₀ is a Bragg diffraction wavelength by _a diffraction grating having _a period Λ _a , that is, λ ₀ = 2nΛ _a , and n is an effective refractive index of a mode propagating in the optical waveguide regions 28 and 32.
[0029]
Here, in each of the first and second optical waveguide devices 14 and 16 are adjusted periodically lambda _a and the period lambda _b of the multi-wavelength diffraction grating, respectively, are assumed to interval Δλ between adjacent reflection peaks are different . In this embodiment, the interval between the reflection peaks of the multi-wavelength diffraction grating 30 of the first optical waveguide device 14 (first wavelength interval) is the interval between the reflection peaks of the multi-wavelength diffraction grating 34 of the second optical waveguide device 16. It is narrower than (second wavelength interval).
[0030]
FIG. 7 is an explanatory diagram for explaining another example of the multi-wavelength diffraction gratings 30 and 34, and FIG. 8 is a diagram showing a refractive index distribution of the multi-wavelength diffraction gratings 30 and 34. The multi-wavelength diffraction gratings 30 and 34 include a plurality of first grating portions 40a having a first refractive index, and a plurality of second grating portions 40b having a second refractive index lower than the first refractive index. have. The first grating portions 40a and the second grating portions 40b are alternately and continuously arranged. These first grating section 40a and the second grating section 40b are arranged alternately at the period lambda _b are formed respectively at a constant period lambda _a, also a first grating section 40a and the second grating section 40b . The multi-wavelength diffraction gratings 30 and 34 can be formed as follows.
[0031]
First, a desired phase grating mask is placed on the side surface of the optical waveguide region of the optical waveguide device, and this mask is irradiated with ultraviolet rays having a sharp spectrum (usually using an excimer laser). Then, utilizing the interference effect of light passing through the phase grating mask, writes the grating of a uniform period lambda _a by intensity of the beam corresponding to the period lambda _a only desired length min. Next, in order to perform the refractive index modulation of the periodic lambda _b, only the region for forming a first grating portion 40a is irradiated with additional light, the region for forming the second grating portion 40b not irradiated with the additional light. By repeating this for each interval lambda _b, multi-wavelength diffraction grating 30, 34 shown in FIG. 7 is formed. Also in such multiwavelength diffraction gratings 30 and 34, a reflection spectrum similar to the reflection spectrum shown in FIG. 6 can be obtained.
[0032]
FIG. 8 is an explanatory diagram for explaining another example of the multi-wavelength diffraction gratings 30 and 34. The multi-wavelength diffraction grating 30 and 34, has a multi-wavelength part of the period lambda _a diffraction grating not in the same period, the chirp structure of changing the period lambda _s to [lambda] _e shown in FIG. The reflection spectra of the multiwavelength diffraction gratings 30 and 34 are shown in FIG. In FIG. 10, each reflection peak of the reflection spectrum is a peak caused by the periods Λ _{s to} Λ _e , and a reflection peak train is present between wavelengths λ _s (= 2nΛ _s ) to λ _e (= 2nΛ _e ). It is formed.
[0033]
Further, another example of the multi-wavelength diffraction gratings 30 and 34 will be described with reference to FIG. The multi-wavelength diffraction gratings 30 and 34 have a plurality of grating portions 38 with different periods of Λ _{s to} Λ _e , and each grating part 38 has a repetition period of a period Λ _b as shown in FIG. ing. Each of these grating portions 38 is spatially overlapped. In this case, it is preferable to apply Gaussian apodization to the individual grating portions 38 to be overwritten so as to lower the side lobes so that adjacent diffraction wavelength spectra are not affected. If the grating portions 38 are spatially overlapped as described above, the length of the multi-wavelength diffraction gratings 30 and 34 and, in turn, the length of the total optical waveguide devices 14 and 16 can be shortened. In addition, also in such multiwavelength diffraction gratings 30 and 34, a reflection spectrum similar to the reflection spectrum shown in FIG. 9 can be obtained.
[0034]
FIG. 11 is an explanatory diagram for explaining another example of the multi-wavelength diffraction gratings 30 and 34. As shown in FIG. 11, multi-wavelength diffraction grating 30 and 34, the concave-convex portion 41 of the periodic lambda _a is configured are arranged at equal intervals in the period lambda _b. The multi-wavelength diffraction gratings 30 and 34 can be formed as follows.
[0035]
First, an under clad layer made of SiO _{2 is formed} on a substrate (for example, a silicon substrate) by chemical vapor deposition (CVD), and a core layer made of SiO ₂ doped with Ge is formed thereon. Film. Next, the core as the optical waveguide region is processed by photolithography and reactive ion etching (RIE). Further, by using a photolithography technique and reactive ion etching (RIE), an uneven portion is formed with a predetermined period along the optical waveguide direction with respect to the processed core. Then, an over clad layer is formed on these by CVD. As described above, a diffraction grating having a complicated pattern can be easily formed by configuring the diffraction grating with the uneven portions provided in the optical waveguide region. In addition, also in such multiwavelength diffraction gratings 30 and 34, a reflection spectrum similar to the reflection spectrum shown in FIG. 6 can be obtained.
[0036]
In the semiconductor laser 10 according to this embodiment, the multiwavelength diffraction gratings 30 and 34 having the above-described configuration formed in the optical waveguide regions 28 and 32 of the first and second optical waveguide devices 14 and 16 have a specific wavelength. Are selectively reflected, whereby a pair of reflectors of the semiconductor laser 10 is formed.
[0037]
Next, the principle that the oscillation wavelength is variable in the semiconductor laser 10 having the above configuration, that is, the operation of the semiconductor laser 10 will be described with reference to FIG.
[0038]
FIG. 12A shows a reflection spectrum at a _first temperature (for example, room temperature) T ₁ of the multi-wavelength diffraction grating 30 of the first optical waveguide device 14. FIG. 12B shows a reflection spectrum at a _first temperature (for example, room temperature) T _{1 included} in the multi-wavelength diffraction grating 34 of the second optical waveguide device 16. Further, FIG. 12C shows a reflection spectrum at a _second temperature T ₂ (higher than the first temperature T ₁ by a predetermined temperature ΔT) included in the multi-wavelength diffraction grating 34 of the second optical waveguide device 16. .
[0039]
Laser oscillation occurs at a longitudinal mode wavelength at which the product of the reflectivity of the multi-wavelength diffraction grating 30 of the first optical waveguide device 14 and the reflectivity of the multi-wavelength diffraction grating 34 of the second optical waveguide device 16 is maximized. obtain. Accordingly, in the state shown in FIG. 12B, the reflection peak wavelength of the multiwavelength diffraction grating 30 of the first optical waveguide device 14 and the reflection peak wavelength of the multiwavelength diffraction grating 34 of the second optical waveguide device 16 are the same. Laser oscillation occurs at the coincident wavelength λ ₁ .
[0040]
Then, the temperature of the optical waveguide region 32 of the second optical waveguide device 16 is changed to the second temperature T ₂ by the temperature adjusting means 18, when changing the refractive index of the optical waveguide region 32, FIG. 12 (c) As shown, the wavelength dependence of the reflection spectrum of the multi-wavelength diffraction grating 34 of the second optical waveguide device 16 changes. That is, the reflection spectrum is shifted to the longer wavelength side by δλ while maintaining the waveform shown in FIG. At this time, the reflection peak of the multi-wavelength diffraction grating 30 of the first optical waveguide device 14, the product of the reflection peak of the multi-wavelength diffraction grating 34 of the second optical waveguide device 16, becomes maximum for the wavelength lambda ₂ , laser oscillation can occur at this wavelength lambda _2.
[0041]
In this way, by changing the refractive index of the optical waveguide region 32 of the second optical waveguide device 16 via the temperature adjusting means 18, the wavelength of laser oscillation can be changed.
[0042]
In this case, by selecting the difference δλ between the reflection peak wavelength width [Delta] [lambda] ₂ of the reflection peak wavelength width [Delta] [lambda] ₁ of the first optical waveguide device 14 and the second optical waveguide device appropriately, the large wavelength variable range by means of the vernier effect Can be obtained.
[0043]
As described above, the semiconductor laser 10 of the present embodiment includes the planar optical waveguides as the first and second optical waveguide devices 14 and 16 in which the multi-wavelength diffraction gratings 30 and 34 are formed. Thus, the manufacture is facilitated as compared with a conventional laser that forms a diffraction grating in a semiconductor. Further, since the optical waveguide region 32 in which the multi-wavelength diffraction grating 34 is formed in the second optical waveguide device 16 is formed mainly of quartz whose refractive index has a small temperature dependence, the temperature change by the temperature adjusting means 18 is performed. Although it is easy to change the reflection spectrum of the multi-wavelength diffraction grating 34 by adjusting the refractive index by the refractive index, the refractive index is stable with respect to temperature changes such as changes in environmental temperature, and temperature control is essential. Therefore, a semiconductor laser having high temperature stability can be obtained. Furthermore, since the refractive index of the optical waveguide region 32 is adjusted by changing the temperature by the temperature adjusting means 18, the oscillation wavelength and the oscillation output can be stabilized as compared with the case where the refractive index is adjusted by the injection current.
[0044]
FIG. 13 shows the temperature dependence of the oscillation wavelength of the semiconductor laser 10 according to this embodiment (indicated by white circles in FIG. 13) and the conventional distributed feedback (DFB) semiconductor laser (indicated by white triangles in FIG. 13). It is a graph which shows sex. As shown in FIG. 13, in the semiconductor laser 10 according to this embodiment, the temperature dependency of the oscillation wavelength is 11.7 pm / ° C., whereas in the conventional DFB laser, the temperature dependency of the oscillation wavelength is 103.9 pm / ° C. ° C. Thus, it can be seen that the semiconductor laser 10 according to the present embodiment has a temperature dependency that is an order of magnitude lower than that of the conventional laser diode and is excellent in temperature stability.
[0045]
Referring to FIG. 12, when the difference δλ between the reflection peak wavelengths in the first and second optical waveguide devices 14 and 16 is 0.4 nm, the oscillation of the semiconductor laser 10 according to the present embodiment. When the temperature dependence of the wavelength is 11.7 pm / ° C., a temperature increase of about 34 ° C. is required to change the oscillation wavelength from λ ₁ to λ ₂ , and the oscillation wavelength is changed from λ ₁ to λ ₄ . This requires an increase in temperature of about 102 ° C.
[0046]
The present invention is not limited to the above-described embodiment, and various modifications can be made.
[0047]
For example, in the above-described embodiment, the first and second optical waveguide devices 14 and 16 are configured as planar optical waveguides. However, as illustrated in FIG. 14, the first optical waveguide device 14 includes an optical waveguide region ( You may comprise with the optical fiber in which the multiwavelength diffraction grating 30 was formed in the core area | region 28. In this case, it is preferable that the optical fiber as the second optical waveguide device 14 is easily and reliably positioned by being inserted and fixed in a V-groove 42 provided on the substrate.
[0048]
Alternatively, as shown in FIG. 15, both the first and second optical waveguide devices 14 and 16 are formed by optical fibers in which multiwavelength diffraction gratings 30 and 34 are formed in optical waveguide regions (core regions) 28 and 32. It may be configured. In this case, it is preferable that the optical fibers as the first and second optical waveguide devices 14 and 16 are inserted and fixed in the V-grooves 42 respectively provided on the substrate because positioning is easy and reliable.
[0049]
【The invention's effect】
According to the present invention, there is provided a semiconductor laser having a variable oscillation wavelength that has high temperature stability and is easy to manufacture.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a semiconductor laser according to an embodiment.
2 is a plan view showing a configuration of the semiconductor laser shown in FIG. 1. FIG.
3 is a diagram showing a cross-sectional structure of a semiconductor optical amplification device when the semiconductor laser shown in FIG. 2 is cut along the line III-III. FIG.
FIG. 4 is a diagram for explaining a spot size conversion unit provided at an end of an active region.
FIG. 5 is a diagram showing an example of the configuration of a multiwavelength diffraction grating.
6 is a diagram showing a reflection spectrum of the multi-wavelength diffraction grating shown in FIG. 5. FIG.
FIG. 7A is a diagram showing another configuration example of the multi-wavelength diffraction grating. FIG. 7B is a diagram showing the refractive index distribution of the multiwavelength diffraction grating shown in FIG.
FIG. 8 is a diagram showing another configuration example of a multiwavelength diffraction grating.
9 is a diagram showing a reflection spectrum of the multi-wavelength diffraction grating shown in FIG. 8. FIG.
FIG. 10 is a diagram illustrating another configuration example of a multiwavelength diffraction grating.
FIG. 11 is a diagram showing another configuration example of a multiwavelength diffraction grating.
FIG. 12 is a diagram for explaining the principle that the oscillation wavelength is variable in the semiconductor laser according to the present embodiment.
13 shows the temperature dependence of the oscillation wavelength of the semiconductor laser according to the present embodiment (indicated by white circles in FIG. 13) and the conventional distributed feedback (DFB) semiconductor laser (indicated by white triangles in FIG. 13). It is a graph which shows.
FIG. 14 is a plan view showing a modification of the semiconductor laser according to the present embodiment.
FIG. 15 is a plan view showing a modification of the semiconductor laser according to the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Semiconductor laser, 12 ... Semiconductor optical amplification device, 14 ... 1st optical waveguide device, 16 ... 2nd optical waveguide device, 18 ... Temperature control means, 20 ... Active region, 22 ... 1st light-projection surface, 24 ... second light exit surface, 26 ... spot size converter, 28,32 ... optical waveguide region, 30,34 ... multi-wavelength diffraction grating, 38 ... grating part, 40a ... first grating part, 40b ... second grating Part, 41 ... uneven part.

Claims (7)

A semiconductor optical amplifying device having an active region and first and second light emitting surfaces facing each other across the active region;
A first light beam optically coupled to the first light exit surface and having a multi-wavelength diffraction grating having a plurality of reflection peaks at first wavelength intervals formed in an optical waveguide region formed mainly of quartz. A waveguide device;
Multi-wavelength diffraction that is optically coupled to the second light exit surface and exhibits a plurality of reflection peaks at a second wavelength interval different from the first wavelength interval in an optical waveguide region formed mainly of quartz. A second optical waveguide device having a grating formed thereon;
Temperature adjusting means for adjusting the refractive index of the optical waveguide region provided in the second optical waveguide device,
The first and second optical waveguide devices are planar optical waveguides, and the first and second optical waveguide devices are one planar optical device provided on the same substrate and formed with the multi-wavelength diffraction grating. It is formed by dividing the waveguide into two, a stepped portion is provided between the first and second optical waveguide devices,
A pair of reflectors is formed by mounting the semiconductor optical amplifying device on the stepped portion and optically coupling the first and second optical waveguide devices formed with a multi-wavelength diffraction grating and the semiconductor optical amplifying device. A semiconductor laser characterized by that.   2. The semiconductor laser according to claim 1, wherein the multi-wavelength diffraction grating of at least one of the first and second optical waveguide devices has a plurality of grating portions with a predetermined period arranged at equal intervals.   The multi-wavelength diffraction grating of at least one of the first and second optical waveguide devices includes a plurality of first grating portions having a first refractive index, and a plurality of second grating portions having a second refractive index. The semiconductor laser according to claim 1, wherein the first grating portion and the second grating portion are alternately and continuously arranged.   2. The semiconductor laser according to claim 1, wherein the multi-wavelength diffraction grating of at least one of the first and second optical waveguide devices has a plurality of chirped grating portions arranged at equal intervals.   The multi-wavelength diffraction grating of at least one of the first and second optical waveguide devices has a plurality of grating portions each having a different period, and each grating portion is spatially arranged. The semiconductor laser according to claim 1.   2. The semiconductor laser according to claim 1, wherein the multi-wavelength diffraction grating includes a concavo-convex portion formed in the optical waveguide region along an optical waveguide direction.   The semiconductor laser according to claim 1, wherein the active region of the semiconductor optical amplification device has a spot size conversion unit.

Images