JP2004342961A - Tunable semiconductor laser and method of manufacturing the same - Google Patents

Abstract

A tunable semiconductor laser having a large tunable width and a method of manufacturing the tunable semiconductor laser having a small amount of heat and capable of avoiding characteristic fluctuation, performance deterioration and reliability deterioration due to heat, and a method of manufacturing the same.
A surface-emitting type sub-semiconductor that generates light having a wavelength shorter than the bandgap wavelength of the tuning layer below a main semiconductor laser in which a carrier is generated in the tuning layer by irradiation of light and the oscillation wavelength changes. The laser 30 is arranged. A lens may be arranged between the main semiconductor laser 10 and the sub semiconductor laser 30.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wavelength tunable semiconductor laser capable of changing an oscillation wavelength using a change in a refractive index caused by optical excitation, and a method for manufacturing the same.
[0002]
[Prior art]
In order to change the oscillation wavelength of the semiconductor laser, it is conceivable to change the band gap of the active layer or change the optical path length in the resonator. However, since it is difficult to change the band gap of the active layer of the completed semiconductor laser, the oscillation wavelength is changed by changing the effective optical path length by changing the refractive index of the semiconductor constituting the resonator. Has been studied.
[0003]
Several methods are known for changing the refractive index of a semiconductor, but the largest change in the refractive index can be expected from a method using a nonlinear optical effect due to carrier excitation. IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 35, NO. 5, MAY 5 (Non-Patent Document 1) proposes a tunable twin guide laser as a wavelength tunable semiconductor laser utilizing this effect.
[0004]
However, in the tunable twin guide laser described above, it is difficult to optimize a complicated current injection structure, and at present, expected characteristics are not obtained. Further, in this structure, a forward current is injected to cause a non-linear optical effect, so that a relatively large control current is required to increase the wavelength variable width. Since the amount of heat generated by the control current is large and the heat source is relatively close to the active layer, there is a problem that characteristic fluctuation, performance deterioration, and reliability deterioration due to heat are inevitable. Also, a large heat sink is required to dissipate heat.
[0005]
In order to solve such a problem, a tunable twin guide laser utilizing a change in the refractive index due to light excitation has been proposed (Japanese Patent Application Laid-Open No. 9-148665 (Patent Document 1)). In this laser, a light emitting diode is arranged at the end of the resonator of the main semiconductor laser, and light generated by the light emitting diode is incident on the light guide layer of the main semiconductor laser to generate carriers in the light guide layer, thereby reducing the refractive index. Is changing. This makes it possible to change the oscillation wavelength while solving the above-mentioned problems.
[0006]
[Patent Document 1]
JP-A-9-148665
[Non-patent document 1]
IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 35, NO. 5, MAY 5
[0007]
[Problems to be solved by the invention]
However, the tunable twin guide laser utilizing the above-described change in the refractive index caused by light excitation has a disadvantage that the wavelength variable width is small. For this reason, there is a demand for a semiconductor laser that generates a small amount of heat and can avoid characteristic fluctuations, performance deterioration and reliability deterioration due to heat, and further has a larger wavelength variable width.
[0008]
In view of the above, it is an object of the present invention to provide a wavelength tunable semiconductor laser having a large wavelength tunable width and a method of manufacturing the same, in which a small amount of heat is generated and characteristic fluctuations due to heat, performance deterioration and reliability reduction can be avoided. It is.
[0009]
[Means for Solving the Problems]
The above-described problem is caused by a main semiconductor laser in which carriers are generated in the tuning layer by irradiation of light and the oscillation wavelength changes, and a light source that irradiates the tuning layer of the main semiconductor laser with light from a direction intersecting the length direction of the tuning layer. And a wavelength tunable semiconductor laser characterized by having the following.
[0010]
The above-mentioned problem is solved by a substrate, a main semiconductor laser formed on a first region of the substrate, wherein carriers are generated in a tuning layer by irradiation of light and an oscillation wavelength is changed, and a main semiconductor laser is formed on a second region of the substrate. Wavelength tunable, comprising: a formed light source; and an optical waveguide layer formed on the substrate and configured to introduce light generated by the light source into the tuning layer from a direction intersecting the length direction of the tuning layer. The problem is solved by a semiconductor laser.
[0011]
The above-mentioned problem is to form a mask having a tuning layer forming region, a photoexcitation layer forming region and an optical waveguide layer forming region on a substrate, and to vapor-grow an optical material inside the opening of the mask. Simultaneously forming a tuning layer, an optical excitation layer and an optical waveguide layer communicating therewith, removing the mask, forming an active layer above the tuning layer, the optical excitation layer, Coating the optical waveguide layer and the active layer with a material having a lower refractive index than those of the active layer and the active layer.
[0012]
In order to obtain a large refractive index change by light excitation, it is effective to generate carriers uniformly over a wide range in the length direction of the tuning layer. For this reason, in the present invention, light is irradiated from a direction crossing the length direction of the tuning layer. As a result, carriers are generated over a wide range in the length direction of the tuning layer, and the refractive index changes. Therefore, it is possible to greatly change the wavelength.
[0013]
Note that it is preferable to arrange a lens between the main semiconductor laser and the light source in order to make the light emitted from the light source efficiently enter the tuning layer.
[0014]
Further, the main semiconductor laser and the light source can be formed on the same substrate. In this case, the manufacturing process is simplified as compared with a case where the main semiconductor laser and the light source are separately manufactured, the size of the wavelength tunable semiconductor laser can be reduced, and the optical axes of the main semiconductor laser and the light source are aligned. There is an advantage that a process is not required.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0016]
(First Embodiment)
FIG. 1 is a sectional view showing a configuration of a wavelength-tunable semiconductor laser (tunable twin guide laser) according to a first embodiment of the present invention, and FIG. 2 is a top view of the same. FIG. 1 shows a cross section taken along the line II in FIG.
[0017]
The wavelength tunable semiconductor laser according to the present embodiment includes a main semiconductor laser 10 and a surface-emitting sub-semiconductor laser 30 disposed below the main semiconductor laser 10 and irradiating the main semiconductor laser 10 from below. I have.
[0018]
The main semiconductor laser 10 is formed using an n-type InP substrate 11. That is, the tuning layer 12 having a multiple quantum well structure is formed on the resonator forming region of the n-type InP substrate 11 and the negative electrode side electrode forming region connected to the resonator forming region. The tuning layer 12 is configured by, for example, multiplexing an InGaAsP layer having a band gap wavelength of 1.25 μm and an InGaAsP layer having a band gap wavelength of 1.10 μm for 20 periods.
[0019]
An n-type InP layer 13 is formed on the tuning layer 12. A negative electrode 24a is formed on the n-type InP layer 13 in the negative electrode forming region. On the other hand, an undoped InGaAsP layer 14, an active layer 15 having a multiple quantum well structure, an undoped InGaAsP layer 16 and an undoped InGaAsP layer 16 having a period of 240 nm and a depth of 35 nm A mesa-shaped laminate is formed by laminating the diffraction grating 17 and the p-type InP layer 18 in this order from below. This mesa-shaped laminate has a stripe shape whose length direction is perpendicular to the paper surface of FIG. 1, and has a mesa width of 1 μm and a stripe length of 800 μm, for example.
[0020]
Each of the InGaAsP layers 14 and 16 has a band gap wavelength of 1.20 μm. The active layer 15 is composed of, for example, seven periods of InGaAsP / InGaAsP layers designed to have an oscillation wavelength of 1.55 μm.
[0021]
A p-type InP layer 19 and an n-type InP layer 20 are laminated in this order from below on both sides in the width direction of the mesa-shaped laminate.
[0022]
A p-type InP layer 21 is formed on the mesa stack and the n-type InP layer 20. A p-type InGaAsP layer 22 having a bandgap wavelength of 1.08 μm is formed on the p-type InP layer 21, and a p-type InGaAsP layer 23 having a bandgap wavelength of 1.3 μm is formed thereon. ing. The structure composed of the p-type InGaAsP layer 23, the p-type InGaAsP layer 22, the p-type InP layer 21, the n-type InP layer 20, the p-type InP layer 19, the n-type InP layer 13, and the tuning layer 12 is shown in FIG. As shown in FIG. The positive electrode 24b is formed on the p-type InGaAsP layer 23.
[0023]
On the other hand, the sub-semiconductor laser 30 is formed using an n-type InP substrate 31. That is, a DBR (Distributed Bragg Reflector) mirror 32 having a multilayer structure in which an n-type InP layer and an n-type InGaAsP layer are alternately laminated is formed on one surface of the n-type InP substrate 31 (the lower side in FIG. 1). Have been. Under the DBR mirror 32, an active layer 33 is formed in a stripe shape having a length in a direction perpendicular to the plane of FIG. The active layer 33 is formed by multiplexing an InGaAsP layer having a band gap wavelength of 1.10 μm and an InGaAsP layer having a band gap wavelength of 1.20 μm for 10 periods.
[0024]
Below the active layer 33, a DBR mirror 34 having a multilayer structure in which n-type InP layers and n-type InGaAsP layers are alternately stacked is formed. An InP layer (Fe-InP layer) 35 doped with Fe is disposed on both sides of the active layer 33 and the DBR mirror 34 in the width direction.
[0025]
A negative electrode 36 a having an opening through which light passes is formed on the n-type InP substrate 31, and a positive electrode 36 b is formed below the DBR mirror 34 and the Fe-InP layer 35. Have been.
[0026]
In the wavelength tunable semiconductor laser of the present embodiment thus configured, when a voltage is applied between the electrodes 24a and 24b of the main semiconductor laser 10, the light generated in the active layer 15 is directed in a direction perpendicular to the plane of FIG. Is output to At this time, when a voltage is applied between the electrodes 36a and 36b of the sub-semiconductor laser 30 to emit light, the tuning layer 12 of the main semiconductor laser 10 is irradiated with light, and an amount of carriers corresponding to the light intensity is generated. The refractive index of the tuning layer 12 changes. Thereby, the optical period of the diffraction grating of the main semiconductor laser 10 changes, so that the oscillation wavelength changes.
[0027]
In this case, in the present embodiment, since the surface emitting laser 30 irradiates light over a wide area of the tuning layer 12 of the main semiconductor laser 10 from below the main semiconductor laser 10, many carriers are generated in the tuning layer 12. Can be done. Thereby, the oscillation wavelength of the main semiconductor laser 10 can be largely changed.
[0028]
Further, since the wavelength tunable semiconductor laser according to the present embodiment generates carriers by irradiating light, the amount of generated heat is small, so that fluctuations in characteristics, performance deterioration and reliability deterioration due to heat can be avoided.
[0029]
Hereinafter, a method of manufacturing the wavelength tunable semiconductor laser according to the present embodiment will be described with reference to the cross-sectional views shown in FIGS.
[0030]
First, a method for manufacturing the main semiconductor laser 10 will be described. First, as shown in FIG. 3A, an n-type InP substrate 11 is prepared. Then, a tuning layer 12 having a multiple quantum well structure is formed on the n-type InP substrate 11 by using a metal organic chemical vapor deposition (MOCVD) method. The tuning layer 12 is configured by multiplexing, for example, an InGaAsP layer having a band gap wavelength of 1.25 μm and an InGaAsP layer having a band gap wavelength of 1.10 μm for 20 periods.
[0031]
Next, as shown in FIG. 3B, an n-type InP layer 13 is formed on the tuning layer 12. An undoped InGaAsP layer 14 having a band gap wavelength of 1.20 μm, an active layer 15 having a multiple quantum well structure, and an undoped InGaAsP layer 16 having a band gap wavelength of 1.20 μm are formed on the n-type InP layer 13. Form sequentially. The multiple quantum well structure of the active layer 15 is composed of, for example, seven periods of InGaAsP / InGaAsP layers designed to have an oscillation wavelength of 1.55 μm.
[0032]
Thereafter, a diffraction grating 17 having a period of 240 nm and a depth of 35 nm is formed on the InGaAsP layer 16. Then, a p-type InP layer 18 is formed on the diffraction grating 17.
[0033]
Next, as shown in FIG. 3C, a stacked body of the p-type InP layer 18, the InGaAsP layer 16, the active layer 15, and the InGaAsP layer 14 is processed into a mesa shape by photolithography.
[0034]
Next, as shown in FIG. 4A, an n-type InP layer 19 is formed on both sides in the width direction of the mesa-shaped laminated body including the p-type InP layer 18, the InGaAsP layer 16, the active layer 15, and the InGaAsP layer 14. And a p-type InP layer 20 is formed. Thereafter, a p-type InP layer 21 is formed on the entire surface. Then, a p-type InGaAsP layer 22 having a bandgap wavelength of 1.08 μm and a p-type InGaAsP layer 23 having a bandgap wavelength of 1.3 μm are sequentially formed on the p-type InP layer 21.
[0035]
Next, as shown in FIG. 4B, the InGaAsP layers 22 and 23, the p-type InP layer 21, the n-type InP layer 20, the p-type InP layer 19, and the n-type InP layer 13 in the resonator forming region are formed by photolithography. Then, the tuning layer 12 is etched to form a mesa resonator, and the n-type InP layer 13 in the negative electrode side electrode formation region is exposed. Then, as shown in FIG. 1, a negative electrode 24a made of a metal film is formed on the n-type InP layer 13, and a positive electrode 24b made of a metal film is formed on the p-type InGaAsP layer 23. Thus, the main semiconductor laser 10 is completed.
[0036]
Hereinafter, a method for manufacturing the sub-semiconductor laser 30 will be described with reference to FIG. First, as shown in FIG. 5A, an n-type InP substrate 31 is prepared. Then, on this n-type InP substrate 31, a DBR mirror 32 having a multilayer structure of an n-type InGaAsP layer and an InP layer is formed.
[0037]
Next, as shown in FIG. 5B, an InGaAsP layer having a band gap wavelength of 1.10 μm and an InGaAsP layer having a band gap wavelength of 1.2 μm are multiplexed for 10 periods, and the tuning layer 12 of the main semiconductor laser 10 is multiplexed. An active layer 33 having a multiple quantum well structure that emits light at a shorter wavelength than that of the active layer 33 is formed. Thereafter, on the active layer 33, a DBR mirror 34 having a multilayer structure of a p-type InGaAsP layer and a p-type InP layer is formed. Then, the DBR mirror 34 and the active layer 33 are processed into a mesa shape by photolithography. Thereafter, an InP layer 35 doped with Fe is formed on both sides of the mesa-shaped DBR mirror 34 and the active layer 33.
[0038]
Next, as shown in FIG. 1, a ring-shaped electrode 36a made of a metal film is formed under the n-type InP substrate 31, and a ring-shaped electrode 36 made of a metal film is formed on the DBR mirror 34 and the Fe-Inp layer 35. The electrode 36b is formed. Thereby, the sub-semiconductor laser 30 is completed.
[0039]
After forming the main semiconductor laser 10 and the sub-semiconductor laser 30 in this way, the sub-semiconductor laser 30 is arranged below the main semiconductor laser 10 and fixed. Thus, the wavelength tunable semiconductor laser of the present embodiment is completed.
[0040]
In the above-described embodiment, a case has been described in which the light output from the sub-semiconductor laser 30 is applied to the tuning layer 12 of the main semiconductor laser 10 to generate carriers. Light emitting diodes or other light sources that emit at shorter wavelengths than the twelve band cap wavelengths may be used.
[0041]
(Modification 1)
FIG. 6 is a cross-sectional view illustrating a first modification of the first embodiment.
[0042]
In the first embodiment, the width of the irradiation area of the light emitted from the sub-semiconductor laser 30 is usually 5 μm or more, and is larger than the mesa width of the main semiconductor laser 10 of 1 μm. In order to efficiently excite the carriers in the tuning layer 12, it is effective to condense the light emitted from the sub-semiconductor laser 30 to approximately the same width as the resonator of the main semiconductor laser 10 using a lens or the like. is there.
[0043]
That is, as shown in FIG. 6, when the cylindrical lens 41 is disposed between the sub semiconductor laser 30 and the main semiconductor laser 10, the light is emitted from the sub semiconductor laser 30 to the tuning layer 12 forming the resonator of the main semiconductor laser 10. Light can be efficiently emitted. This makes it possible to further increase the wavelength variable width of the main semiconductor laser 10 as compared with the first embodiment.
[0044]
(Modification 2)
FIG. 7 is a cross-sectional view showing Modification Example 2 of the first embodiment.
[0045]
In the first embodiment, the sub-semiconductor laser 30 is arranged below the main semiconductor laser 10, but may be arranged on the side of the main semiconductor laser 10 as shown in FIG. Also in this case, the light emitted from the sub-semiconductor laser 30 can uniformly irradiate the tuning layer 12 constituting the resonator of the main semiconductor laser 10 over a wide range. Also in Modification 2, the same effects as those of the first embodiment can be obtained.
[0046]
(Modification 3)
FIG. 8 is a cross-sectional view showing a third modification of the first embodiment.
[0047]
In the third modification, the sub-semiconductor laser 30 is arranged on the side of the main semiconductor laser 10, and a cylindrical lens 41 is arranged between the main semiconductor laser 10 and the sub-semiconductor laser 30. Also in the third modification, the same effect as the first modification can be obtained.
[0048]
(Second embodiment)
FIG. 9 is a sectional view showing a configuration of a wavelength tunable semiconductor laser (tunable twin guide laser) according to the second embodiment of the present invention.
[0049]
In the wavelength tunable semiconductor laser of the present embodiment, the main semiconductor laser 50 and the sub semiconductor laser 70 are formed on the same n-type InP substrate 51.
[0050]
That is, in the main semiconductor laser formation region, the tuning layer 52c having a band gap wavelength of 1.3 μm is formed on the n-type InP substrate 51. On the tuning layer 52c, an n-type InP layer 53, an active layer 54 having a multiple quantum well structure, and a p-type InP layer 55 are formed in this order from the bottom. The stacked body of the n-type InP layer 53, the active layer 54, and the p-type InP layer 55 is formed in a mesa shape having a longitudinal direction perpendicular to the plane of FIG. The width of the mesa laminate is, for example, 1 μm.
[0051]
A p-type InP layer 56 and an n-type InP layer 57 are formed in this order on both sides in the width direction of the mesa-shaped laminate in this order. A p-type InP layer 58 is formed on the p-type InP layer 55 and the n-type InP layer 57, and a p-type InGaAsP layer 59 is formed on the p-type InP layer 58. These p-type InP layers 58 and p-type InGaAsP layers 59 are processed into a mesa shape. The positive electrode 71c of the main semiconductor laser 50 is formed on the InGaAsP layer 59.
[0052]
On the other hand, in the sub-semiconductor laser formation region, a light excitation layer 52 a having a band gap wavelength of 1.2 μm is formed on the n-type InP substrate 51. A p-type InP layer 58 is formed on the light excitation layer 52a, and a p-type InGaAsP layer 59 is formed on the p-type InP layer 58. On the p-type InGaAsP layer 59, a positive electrode 71b of the sub-semiconductor laser 70 is formed. A plurality of sub-semiconductor lasers 70 are arranged along the longitudinal direction of the tuning layer 52c of the main semiconductor laser 50 (the direction perpendicular to the plane of FIG. 9).
[0053]
An optical waveguide layer 52b having a band gap wavelength of 1.15 μm is formed on the n-type InP substrate 51 between the main semiconductor laser formation region and the sub semiconductor laser formation region. The upper surface and side surfaces of the optical waveguide layer 52b are covered with a p-type InP layer 58. On the lower side of the n-type InP substrate 51, a negative electrode 71a common to the main semiconductor laser 50 and the sub semiconductor laser 70 is formed.
[0054]
In order to confine light in the resonator and the optical waveguide layer 52b, the refractive indexes of the p-type InP layer 56, the n-type InP layer 57, and the p-type InP layer 58 are determined by the active layer 54, the light excitation layer 52a, and the optical waveguide layer 52b. Is required to be lower than the refractive index.
[0055]
In the wavelength tunable semiconductor laser according to the present embodiment thus configured, when a voltage is applied between the electrodes 71a and 71c, light generated in the active layer 54 is output in a direction perpendicular to the plane of FIG. At this time, when a voltage is applied between the electrodes 71b and 71c, light is generated in the light excitation layer 52a. This light is introduced into the tuning layer 52 of the main semiconductor laser 71c through the optical waveguide layer 52b. As a result, an amount of carriers corresponding to the light intensity is generated in the tuning layer 53, and the refractive index changes. Thereby, the oscillation wavelength of the main semiconductor laser 50 changes.
[0056]
In this case, in the present embodiment, the tuning layer 52c is irradiated from the side of the main semiconductor laser 50 to the tuning layer 52c over a wide range, so that the oscillation wavelength can be largely changed. In the present embodiment, in addition to obtaining the same effects as those of the first embodiment, the effect that the assembling work for aligning the optical axes of the main semiconductor laser 50 and the sub-semiconductor laser 70 becomes unnecessary is obtained. Play.
[0057]
Hereinafter, a method of manufacturing the wavelength tunable semiconductor laser according to the present embodiment will be described with reference to a plan view of FIG. 10 and cross-sectional views of FIGS. The arrows in FIG. 10 indicate the emission direction of light from the main semiconductor laser 50.
[0058]
First, SiO 2 is deposited on the n-type semiconductor ₂ Form a film. Then, as shown in FIG. ₂ By patterning the film, SiO having an opening through which the photoexcitation layer forming region, the optical waveguide layer forming region and the tuning layer forming region are exposed ₂ A mask 61 is formed.
[0059]
Next, as shown in FIG. 11A, InGaAsP is grown on the n-type InP substrate 51 exposed from the opening of the mask 61 by using a metal organic chemical vapor deposition method, and a photo-excitation layer made of InGaAsP is formed. 52a, an optical waveguide layer 52b, and a tuning layer 52c are formed. At this time, if the conditions during the metalorganic vapor phase epitaxy are set so that the band gap wavelength of the tuning layer 52c becomes 1.3 μm, the difference in the diffusion length between the In atoms and the Ga atoms causes the SiO 2 to grow. ₂ In portions not covered by the mask 61, a composition distribution corresponding to the opening width occurs. As a result, the band gap wavelength of the light excitation layer 52a is about 1.2 μm, and the band gap wavelength of the optical waveguide layer 52b is about 1.15 μm.
[0060]
Next, SiO 2 ₂ After removing the mask 61 by wet etching, as shown in FIG. ₂ A mask 62 is formed.
[0061]
Next, as shown in FIG. 12A, an n-type InP layer 53, an active layer 54 having a multiple quantum well structure, and a p-type InP layer 55 are sequentially grown on the tuning layer 52c. The multiple quantum well structure of the active layer 54 is composed of seven periods of InGaAsP / InGaAsP layers designed to have an oscillation wavelength of 1.55 μm.
[0062]
Next, as shown in FIG. 12B, SiO 2 is formed on the p-type InP layer 55. ₂ A mask 63 is formed. Then, the stacked body of the p-type InP layer 55, the active layer 54, and the n-type InP layer 53 is etched into a mesa shape.
[0063]
Next, as shown in FIG. 13A, the p-type InP layers 56 and n are formed on both sides in the width direction of the mesa-shaped laminate including the p-type InP layer 55, the active layer 54, and the n-type InP layer 53. The type InP layer 57 is formed in this order from below. Thereafter, as shown in FIG. ₂ The masks 62 and 63 are removed by wet etching.
[0064]
Next, as shown in FIG. 14A, a p-type InP layer 58 is formed on the entire upper surface of the n-type InP substrate 51, and the surface thereof is flattened. Thereafter, a p-type InGaAsP layer 59 is formed on the p-type InP layer 58. The p-type InGaAsP layer 59 has, for example, a thickness of about 0.1 μm, a band gap wavelength of 1.3 μm, and a p-type impurity concentration of 8 × 10 ¹⁸ cm ^-3 And
[0065]
Next, as shown in FIG. 14 (b), a predetermined pattern of SiO 2 is formed on the p-type InGaAsP layer 59. ₂ A mask 64 is formed. Then, as shown in FIG. 15, the p-type InGaAsP layer 59 and the p-type InP layer 58 are etched, and the outer shapes of the main semiconductor laser 50 and the sub semiconductor laser 70 are processed into a mesa shape.
[0066]
Next, after removing the mask 64, as shown in FIG. 9, an electrode 71a is formed on the lower surface of the n-type semiconductor substrate 51, and an electrode 71b is formed on the p-type InGaAsP layer 59 of the sub-semiconductor laser 70. An electrode 71c is formed on the p-type InGaAsP layer 59 of the semiconductor laser 50. Thus, the wavelength tunable semiconductor laser of the present embodiment is completed.
[0067]
In the method of manufacturing the wavelength tunable semiconductor laser according to the present embodiment described above, ₂ Since the light excitation layer 52a, the optical waveguide layer 52b, and the tuning layer 52c having different band gap wavelengths are simultaneously formed by utilizing the difference in the opening width of the mask 61, the number of manufacturing steps is small, and the wavelength tunable semiconductor laser is relatively easily manufactured. can do.
[0068]
Further, in the method of manufacturing the wavelength tunable semiconductor laser according to the present embodiment, since the main semiconductor laser 50 and the sub-semiconductor laser 70 are formed on the same substrate, the optical axes of the main semiconductor laser 50 and the sub-semiconductor laser 70 are aligned. There is an advantage that no assembling step is required.
[0069]
(Supplementary Note 1) A main semiconductor laser in which carriers are generated in a tuning layer by light irradiation and the oscillation wavelength changes, and a light source that irradiates the tuning layer of the main semiconductor laser with light in a direction intersecting the length direction of the tuning layer. 1. A wavelength tunable semiconductor laser comprising:
[0070]
(Supplementary note 2) The wavelength tunable semiconductor laser according to supplementary note 1, wherein a lens is disposed between the light source and the main semiconductor laser.
[0071]
(Supplementary note 3) The wavelength tunable semiconductor laser according to supplementary note 1, wherein the light source is a surface emitting laser.
[0072]
(Supplementary note 4) The wavelength tunable semiconductor laser according to supplementary note 1, wherein the light source is a light emitting diode.
[0073]
(Supplementary note 5) The wavelength tunable semiconductor laser according to supplementary note 1, wherein the light source generates light having a wavelength shorter than a band gap wavelength of the tuning layer.
[0074]
(Supplementary Note 6) A substrate, a main semiconductor laser formed on a first region of the substrate, wherein carriers are generated in a tuning layer by irradiation of light to change an oscillation wavelength, and a main semiconductor laser formed on a second region of the substrate. A wavelength tunable semiconductor, comprising: a light source formed on the substrate; and an optical waveguide layer formed on the substrate and for introducing light generated by the light source into the tuning layer from a direction intersecting the length direction of the tuning layer. laser.
[0075]
(Supplementary Note 7) A step of forming a mask in which a tuning layer forming region, a photoexcitation layer forming region, and an optical waveguide layer forming region are opened on a substrate, and vapor-phase growing an optical material inside the opening of the mask, Simultaneously forming a tuning layer, a photoexcitation layer, and an optical waveguide layer communicating therewith; removing the mask; forming an active layer above the tuning layer; Coating the waveguide layer and the active layer with a material having a lower refractive index than the wavelength layer and the active layer.
[0076]
(Supplementary note 8) The method for producing a wavelength-tunable semiconductor laser according to supplementary note 7, wherein a plurality of the photoexcitation layers and the optical waveguide layers are formed along a length direction of the tuning layer.
[0077]
【The invention's effect】
As described above, according to the wavelength tunable semiconductor laser of the present invention, since the tuning layer of the main semiconductor laser is irradiated with light from a direction intersecting the length direction of the tuning layer, a wide range in the length direction of the tuning layer is provided. , And the refractive index changes. This makes it possible to greatly change the oscillation wavelength of the main semiconductor laser. In addition, since carriers are generated by light, the amount of heat generated is small, and fluctuations in characteristics, performance deterioration and reliability deterioration due to heat can be avoided.
[0078]
According to the method of manufacturing a wavelength tunable semiconductor laser of the present invention, the photoexcitation layer, the optical waveguide layer, and the tuning layer having different bandgap wavelengths are formed simultaneously by utilizing the difference in the opening width of the mask. It can be easily manufactured. Further, according to the present invention, since the main semiconductor laser and the light source are formed on the same substrate, there is an advantage that an assembly step of aligning the optical axis of the main semiconductor laser and the light source is not required.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a configuration of a wavelength tunable semiconductor laser according to a first embodiment of the present invention.
FIG. 2 is a top view of the wavelength tunable semiconductor laser according to the first embodiment.
FIG. 3 is a sectional view (part 1) illustrating the method of manufacturing the main semiconductor laser of the wavelength-tunable semiconductor laser according to the first embodiment;
FIG. 4 is a sectional view (part 2) illustrating the method for manufacturing the main semiconductor laser of the wavelength tunable semiconductor laser according to the first embodiment;
FIG. 5 is a sectional view illustrating the method of manufacturing the sub-semiconductor laser of the wavelength-tunable semiconductor laser according to the first embodiment;
FIG. 6 is a cross-sectional view illustrating a first modification of the first embodiment.
FIG. 7 is a cross-sectional view showing Modification 2 of the first embodiment.
FIG. 8 is a cross-sectional view showing a third modification of the first embodiment.
FIG. 9 is a sectional view showing a configuration of a wavelength tunable semiconductor laser according to a second embodiment of the present invention.
FIG. 10 is a diagram (part 1) illustrating the method of manufacturing the wavelength-tunable semiconductor laser according to the second embodiment.
FIG. 11 is a diagram (part 2) illustrating the method of manufacturing the wavelength-tunable semiconductor laser according to the second embodiment.
FIG. 12 is a diagram (part 3) illustrating the method of manufacturing the wavelength-tunable semiconductor laser according to the second embodiment.
FIG. 13 is a diagram (No. 4) illustrating the method of manufacturing the wavelength-tunable semiconductor laser according to the second embodiment.
FIG. 14 is a diagram (No. 5) illustrating the method of manufacturing the wavelength-tunable semiconductor laser according to the second embodiment.
FIG. 15 is a diagram (part 6) illustrating the method of manufacturing the wavelength-tunable semiconductor laser according to the second embodiment.
[Explanation of symbols]
10,50 ... Main semiconductor laser,
11, 31, 51... N-type InP substrate,
12, 52c ... tuning layer,
13, 20, 53, 57 ... n-type InP layer,
14, 16 ... undoped InGaAsP layer,
15, 33, 54 ... active layer,
17 ... Diffraction grating,
18, 19, 21, 55, 56, 58... P-type InP layer;
22, 23, 59 ... p-type InGaAsP layer,
30, 70 ... sub-semiconductor laser,
32, 34 ... DBR mirror,
35 ... Fe-InP layer,
41 ... Lens,
52a ... photoexcitation layer,
52b: waveguide layer,
61, 62, 63, 64: Mask.

Claims (5)

A main semiconductor laser in which carriers are generated in the tuning layer by light irradiation and the oscillation wavelength changes,
A wavelength tunable semiconductor laser, comprising: a light source for irradiating light to a tuning layer of the main semiconductor laser from a direction intersecting a longitudinal direction of the tuning layer. The tunable semiconductor laser according to claim 1, wherein a lens is disposed between the light source and the main semiconductor laser. The tunable semiconductor laser according to claim 1, wherein the light source generates light having a wavelength shorter than a band gap wavelength of the tuning layer. Board and
A main semiconductor laser formed on the first region of the substrate, wherein carriers are generated in the tuning layer by irradiation of light and the oscillation wavelength changes;
A light source formed on a second region of the substrate;
An optical waveguide layer formed on the substrate and introducing light generated by the light source into the tuning layer from a direction intersecting the length direction of the tuning layer. On the substrate, a step of forming a mask in which the tuning layer forming region, the light excitation layer forming region and the optical waveguide layer forming region are opened,
A step of vapor-growing an optical material inside the opening of the mask to simultaneously form a tuning layer, a photoexcitation layer and an optical waveguide layer communicating between them,
Removing the mask;
Forming an active layer above the tuning layer;
Coating the optical excitation layer, the optical waveguide layer, and the active layer with a material having a lower refractive index than those of the light excitation layer, the optical waveguide layer, and the active layer.

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