JP2013243169A - Semiconductor photonic device and optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively radiate heat generated around the center of a resonator of a semiconductor photonic device to the outside.SOLUTION: A semiconductor photonic device 100A comprises: a semiconductor substrate 1; an optical waveguide composed of at least a part of a semiconductor lamination part including a clad layer and an active layer stacked above the semiconductor substrate 1; an AlN embedded part 18 which is embedded in a groove formed at least under the optical waveguide and inside the semiconductor substrate 1 and formed by a material having thermal conductivity higher than that of a material for forming the semiconductor substrate 1; a p electrode 15; a silicon oxide film 14 provided on an undersurface of the p electrode 15; and an AlN film 13 formed between the silicon oxide film 14 and the semiconductor lamination part and formed by a material which is an insulating material and has thermal conductivity higher than that of a material for forming the semiconductor lamination part.

Description

  The present invention relates to a semiconductor optical device and an optical module.

  When light is output by injecting a current into the semiconductor optical device, the light output may become unstable due to a temperature rise due to heat generation from the light emitting portion of the semiconductor optical device. Therefore, the invention described in Patent Document 1 below proposes a technique for stably operating a semiconductor optical device by suppressing deterioration of the emission end face by using a chemically and thermally stable film for the emission end face. Yes.

JP 2003-264333 A

  However, although the semiconductor optical device of Patent Document 1 can improve the heat dissipation near the exit end face, it cannot improve the heat dissipation near the center of the resonator. In fact, in the semiconductor optical device, when the heat flow path during heat radiation is calculated, it can be seen that the heat generation near the center of the resonator is large and the heat generation near the center of the resonator is diffused isotropically. Accordingly, it is important to effectively dissipate heat generated near the center of the resonator in order to stably operate the semiconductor optical device even in a wide temperature range.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a semiconductor optical device and an optical module that can effectively dissipate heat generated inside the semiconductor optical device to the outside. There is.

  In order to achieve the above object, a semiconductor optical device according to the present invention includes an optical waveguide comprising a semiconductor substrate and at least a part of a semiconductor laminated portion including a clad layer and an active layer laminated above the semiconductor substrate. And a heat conduction portion formed of a material having a higher thermal conductivity than a material forming the semiconductor substrate, embedded in a groove formed at least under the optical waveguide and inside the semiconductor substrate. It is characterized by that.

  In one embodiment of the present invention, the semiconductor optical device further includes an etching stop layer provided on an upper surface of the semiconductor substrate, and the groove formed in the semiconductor substrate is formed from the lower surface of the semiconductor substrate. It may be formed by etching up to the etching stop layer.

  In one embodiment of the present invention, the semiconductor optical device further includes an n-electrode, the upper surface of the heat conducting unit is in contact with the etching stop layer, and the lower surface of the heat conducting unit is in contact with the n electrode. Also good.

  In one embodiment of the present invention, the semiconductor optical device further includes an n-electrode formed so as to be in contact with the side surface of the groove and the etching stopper layer, and the side surface of the groove is formed to be vertical. The heat conduction part may be embedded in the groove after the n-electrode is formed.

  In one embodiment of the present invention, the heat conducting unit is a compound containing any of aluminum, nitrogen, silicon, carbon, oxygen, zinc, titanium, and niobium, gold, silver, copper, platinum, titanium, chromium, and molybdenum. , Tungsten, nickel, or a combination of these materials may be used.

  In one embodiment of the present invention, a distance between the heat conducting unit and the active layer may be 20 μm or less.

  In one embodiment of the present invention, the semiconductor optical element is made of an insulating material between a p-electrode, an insulating film provided on a lower surface of the p-electrode, and the insulating film and the semiconductor stacked portion. It is also possible to further include an insulating heat conductive portion formed of a material having a higher thermal conductivity than the material forming the semiconductor stacked portion.

  The semiconductor optical device according to the present invention includes a semiconductor substrate, an optical waveguide constituted by at least a part of a semiconductor stacked portion including a clad layer and an active layer stacked above the semiconductor substrate, a p-electrode, and the p-electrode An insulating film provided on the lower surface of the electrode, and an insulating material between the insulating film and the semiconductor stacked portion, and a material having higher thermal conductivity than the material forming the semiconductor stacked portion And an insulating heat conducting part.

  In one embodiment of the present invention, at least a part of the insulating heat conducting portion may be embedded in an active layer isolation trench formed to reduce the capacity of the active layer.

  In one aspect of the present invention, the semiconductor optical device includes an electrically insulated heat dissipation electrode provided on at least a part of the upper surface of the insulating heat conducting portion, and a support portion that supports the semiconductor substrate. And a wire connecting the electrode provided on the support portion and the heat dissipation electrode.

  In one embodiment of the present invention, the insulating heat conducting part is made of a material made of any one or a combination of compounds containing any of aluminum, nitrogen, silicon, carbon, oxygen, zinc, titanium, and niobium. It may be formed by using.

  An optical module according to the present invention includes the semiconductor optical device.

  ADVANTAGE OF THE INVENTION According to this invention, the heat flow inside a semiconductor optical element can be effectively thermally radiated outside by providing the heat flow path which escapes the heat generation inside a semiconductor optical element outside. Thereby, the semiconductor optical device can be stably operated in a wide temperature range.

1 is a cross-sectional view of a semiconductor optical device according to a first embodiment. 1 is a plan view of a semiconductor optical device according to a first embodiment. It is a figure explaining the manufacturing process of the semiconductor optical element which concerns on 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor optical element which concerns on 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor optical element which concerns on 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor optical element which concerns on 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor optical element which concerns on 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor optical element which concerns on 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor optical element which concerns on 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor optical element which concerns on 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor optical element concerning 2nd Embodiment. It is a figure explaining the manufacturing process of the semiconductor optical element concerning 2nd Embodiment. It is sectional drawing of the semiconductor optical element concerning 2nd Embodiment. It is sectional drawing of the semiconductor optical element concerning 3rd Embodiment. It is a figure explaining an example of the optical module M carrying the semiconductor optical element concerning this embodiment.

  Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings. In addition, in each figure explaining embodiment of this invention, it has shown that the member to which the same code | symbol was attached | subjected is the member which has the same or the same function, and repeated description is abbreviate | omitted for the simplicity of description.

[First Embodiment]
First, a semiconductor optical device according to the first embodiment of the present invention will be described with reference to FIGS. Here, FIG. 1 is a cross-sectional view of the semiconductor optical device according to the first embodiment, and FIG. 2 is a plan view of the semiconductor optical device according to the first embodiment. 3 to 10 are views for explaining a manufacturing process of the semiconductor optical device according to the first embodiment.

  The semiconductor optical device according to the first embodiment is the one in which the present invention is applied to a ridge waveguide type semiconductor optical device, and the oscillation wavelength of the ridge waveguide type semiconductor optical device is about 1.3 μm. A configuration example is shown. Details of the configuration of the semiconductor optical device according to the first embodiment will be described below.

  First, reference numerals in FIGS. 1 and 2 will be described. 1 and 2, 1 is a semiconductor substrate made of n-type InP (indium phosphide), 2 is an etching stop layer made of n-type InGaAsP, 3 is a buffer layer made of n-type InP, and 4 is made of n-type InP. The clad layer 5 is an n-type InAlAs (indium aluminum arsenide) layer, 6 is an InGaAlAs-based strained multiple quantum well structure active layer composed of an InGaAlAs (indium gallium aluminum arsenide) well layer and an InGaAlAs barrier layer, 7 is a p-type InAlAs layer, 8 is a cladding layer made of p-type InP, and 10 is a contact layer made of p-type InGaAs (indium gallium arsenide). A hetero barrier reduction layer made of p-type InGaAsP (indium gallium arsenide phosphorus) having a thickness of 30 nm may be provided between the cladding layer 8 and the contact layer 10.

  1 and 2, 13 is an AlN film, 14 is a silicon oxide film, 15 is a p-electrode, 16 is a pad electrode, 17 is a heat dissipation electrode provided on the element upper side, 18 is an AlN film, 19 is an n-electrode, 20 is a heat dissipation electrode provided on the submount side, 21 is a wire connecting the heat dissipation electrode 17 and the heat dissipation electrode 20, 22 is solder, 23 is a submount electrode, and 24 is a submount.

  In the semiconductor optical device according to the first embodiment, at least inside the semiconductor substrate 1 and in the lower part of the optical waveguide, a heat conducting portion made of a material having higher thermal conductivity than the material constituting the semiconductor substrate 1 An AlN buried portion 18 is provided. Here, the upper surface of the AlN buried portion 18 is in contact with the etching stopper layer 2, and the lower surface of the AlN buried portion 18 is in contact with the n electrode 19. Thus, a heat flow path is formed so that the heat generated from the active layer 6 flows to the submount 24 through the AlN buried portion 18, the n electrode 19, the solder 22, and the submount electrode 23.

  In addition, the semiconductor optical device according to the first embodiment is an insulating heat conductive layer made of a material having an insulating property and a high thermal conductivity so as to fill the capacitance reducing groove for reducing the capacitance. An AlN film 13 is formed. For example, the thermal conductivity of the insulating thermal conductive layer may be higher than that of the material constituting the semiconductor substrate, the active layer, and the cladding layer. Here, as shown in FIG. 2, the AlN film 13 is large enough to cover at least the lower surface of the silicon oxide film 14, the p electrode 15, the pad electrode 16, and the heat dissipation electrode 17 disposed above the AlN film 13. It is formed with. Then, a heat radiation electrode 17 is provided so as to be in contact with the upper surface of the AlN film 13, and a heat flow path in which heat from the active layer 6 flows to the submount 24 through the AlN film 13, the heat radiation electrode 17, the wire 21, and the heat radiation electrode 20. Is forming.

[Manufacturing Process of Semiconductor Optical Device According to First Embodiment]
Next, an example of a manufacturing process of the semiconductor optical device according to the first embodiment will be described with reference to FIGS.

  First, as shown in FIG. 3, a semiconductor substrate 1 made of n-type InP (indium phosphide) is prepared, and an etching made of n-type InGaAsP with a thickness of 50 nm is formed thereon using a well-known metal organic chemical vapor deposition method. Stop layer 2, buffer layer 3 made of n-type InP with a thickness of 5000 nm, clad layer 4 made of n-type InP with a thickness of 500 nm, n-type InAlAs (indium aluminum arsenide) layer 5 with a thickness of 5 nm, InGaAlAs with a thickness of 5 nm (Indium gallium aluminum arsenide) InGaAlAs strained multiple quantum well structure active layer 6 comprising a well layer and an InGaAlAs barrier layer having a thickness of 8 nm, a p-type InAlAs layer 7 having a thickness of 30 nm, and a clad layer comprising p-type InP having a thickness of 1600 nm 8. Co-crystal made of p-type InGaAs (indium gallium arsenide) with a thickness of 200 nm It is successively grown a contact layer 10. Here, a hetero barrier reduction layer made of p-type InGaAsP (indium gallium arsenide phosphorus) having a thickness of 30 nm may be provided between the cladding layer 8 and the contact layer 10.

  Thereafter, as shown in FIG. 4, the light guide region 11 is formed by etching up to the strained multiple quantum well structure active layer 6 and metal organic vapor phase epitaxy. FIG. 4 is a top view of the semiconductor optical device in the manufacturing process.

  In the first embodiment, the InGaAlAs-based material is used for the strained multiple quantum well structure active layer 6, but an InGaAsP-based material may be used.

  Next, as shown in FIG. 5, the bottom of the contact layer 10 made of InGaAs is extended to the middle of the clad layer 8 made of p-type InP using a known photolithography technique (etching technique using a photoresist film as a mask). Etch. As a result, a ridge waveguide 12 made of ridge-shaped p-type InP having a width of 1.5 μm is formed at the center.

  Next, as shown in FIG. 6, a capacitance reduction groove (active layer separation groove) for reducing electrostatic capacity is formed by using a photolithography technique, and an AlN film 13 having a thickness of 200 nm is formed so as to fill the groove. accumulate.

  Here, as shown in FIG. 7, the AlN film 13 is disposed so as to cover the upper surface of the light guide region 11 when the semiconductor optical device in the manufacturing process is viewed from the upper surface. Thereafter, after depositing a 300 nm-thickness silicon oxide film 14 by CVD, the silicon oxide film 14 provided on a part of the upper surface of the ridge waveguide 12 is removed by dry etching using a photoresist film as a mask. A part of the upper surface of the ridge waveguide 12 is exposed.

  Next, as shown in FIG. 8, a p-electrode 15 electrically connected to the ridge waveguide 12 and a pad electrode 16 for wire bonding are formed, and at the same time, heat dissipation is performed on a part of the upper surface of the AlN film 13. For this purpose, a heat radiation electrode 17 is formed. At this time, the p electrode 15 and the pad electrode 16 are electrically insulated from the heat radiation electrode 17 for heat radiation.

  Next, as shown in FIG. 9, after the semiconductor substrate 1 is polished, the semiconductor substrate 1 is etched using a photolithography technique to form a groove for heat dissipation. Etching proceeds with time and the groove becomes deeper, but the depth of the groove is controlled by the etching stop layer 2 having a different etching selectivity.

  Next, as shown in FIG. 10, after depositing an AlN buried portion 18 in a groove formed in the semiconductor substrate 1, an n-electrode 19 is formed.

  Thereafter, the semiconductor substrate 1 is cleaved into a bar shape having a resonator length of 200 μm, a multilayer reflective film is formed on the end face of the resonator, and then a chip is formed into a semiconductor optical element having a width of 400 μm, as shown in FIGS. A ridge waveguide type semiconductor optical device having such an oscillation wavelength of 1.3 μm is completed. When mounted on the submount 24, the heat radiation electrode 17 and the heat radiation electrode 20 on the submount side are connected by the Au wire 21 to enhance heat dissipation.

  As a result of current injection to the semiconductor optical device according to the first embodiment, continuous laser oscillation was performed at a threshold current of 15 mA at an element temperature of 100 ° C., and an oscillation spectrum was observed at a wavelength of 1315 nm. When DC current was applied, the light output saturation current value due to self-heating of the IL curve achieved 115 mA, and sufficient IL linearity was obtained up to 100 ° C. Furthermore, due to the improvement in heat dissipation, the temperature dependency of the characteristics has been reduced, and the temperature dependency of the slope efficiency between −20 ° C. and 100 ° C. has achieved a very small value of 2.0 dB.

[Second Embodiment]
Next, a semiconductor optical device according to a second embodiment of the present invention will be described with reference to FIGS. The semiconductor optical device according to the second embodiment is different from the semiconductor optical device according to the first embodiment in the shape of the heat conduction layer provided in the semiconductor substrate 1 and the configuration of the n-electrode 19. Hereinafter, the configuration of the semiconductor optical device according to the second embodiment will be described together with the manufacturing process thereof.

  Here, the manufacturing process of the semiconductor optical device according to the second embodiment is the same as the manufacturing process of the semiconductor optical device according to the first embodiment up to the steps described with reference to FIGS. Is omitted. Differences from the semiconductor optical device according to the first embodiment will be described below with reference to FIGS.

  Next, as shown in FIG. 11, after polishing the semiconductor substrate 1 after the steps up to FIG. 8, a groove is formed so that the etching side surface is vertical by using a photolithography technique and a dry etching technique. Groove formation by dry etching is time-controlled according to the etching rate so that the thickness up to the etching stop layer 2 is 20 nm. Thereafter, etching is performed up to the etching stop layer 2 by wet etching.

  Next, as shown in FIG. 12, the n-electrode 19 is formed along the surface of the groove formed in the semiconductor substrate 1, and the stress concentration of the semiconductor optical device is reduced in the remaining groove space, so that the semiconductor substrate 1 The AlN buried portion 25 is deposited using AlN, which is a material having higher thermal conductivity than the material constituting the material. The AlN buried portion 25 has a thermal expansion coefficient comparable to that of InP, and thus has an effect of reducing stress concentration, and also has a role of a heat dissipation effect because of its high thermal conductivity. Further, a material other than AlN may be used as long as it has a thermal expansion coefficient close to InP and higher thermal conductivity than InP.

  Thereafter, the semiconductor substrate 1 is cleaved into a bar having a resonator length of 200 μm, a multilayer reflective film is formed on the end face of the resonator, and then a chip is formed into a semiconductor optical device having a width of 400 μm, thereby generating an oscillation as shown in FIG. A ridge waveguide type semiconductor optical device having a wavelength of 1.3 μm is completed. When mounted on the submount 24, the heat dissipation electrode 17 and the heat dissipation electrode 20 on the submount side are connected by the Au wire 21 to enhance heat dissipation.

  As a result of current injection into the semiconductor optical device, continuous laser oscillation was observed at a threshold current of 14 mA at an element temperature of 100 ° C., and an oscillation spectrum was observed at a wavelength of 1315 nm. When DC current was applied, the light output saturation current value due to self-heating of the IL curve achieved 120 mA, and sufficient IL linearity was obtained up to 100 ° C. Furthermore, due to the improvement in heat dissipation, the temperature dependency of the characteristics has been reduced, and the temperature dependency of the slope efficiency between −20 ° C. and 100 ° C. has achieved a very small value of 1.9 dB.

[Third Embodiment]
In the above first and second embodiments, the example in which the present invention is applied to a ridge waveguide type semiconductor optical device has been described. However, the present invention is similarly applied to a buried waveguide type semiconductor optical device. Can do. Therefore, an example in which the present invention is applied to a buried waveguide type semiconductor optical device will be described below as a third embodiment.

  FIG. 14 shows a cross-sectional view of a semiconductor optical device according to the third embodiment. In the semiconductor optical device shown in FIG. 14, AlN, which is a thermal conductor made of a material (in this case, AlN) having a higher thermal conductivity than InP, which is a material of the semiconductor substrate, provided inside the semiconductor substrate 1. Although the embedding portion 18 is configured in the same manner as in the first embodiment, it may be configured in the same manner as in the second embodiment.

  Also in the semiconductor optical device according to the third embodiment, an AlN film which is an insulating heat conductive layer made of a material having an insulating property and a high heat conductivity is formed on the buried layers on both sides of the cladding layer. 13 is formed. Here, as shown in FIG. 14, a heat dissipation electrode 17 is provided so as to be in contact with the upper surface of the AlN film 13, and heat generated from the active layer 6 is sublimated through the AlN film 13, the heat dissipation electrode 17, the wire 21, and the heat dissipation electrode 20. A heat flow path that flows to the mount 24 is formed.

[Modification]
In the above embodiment, the example in which AlN is used as the material of the insulating thermal conductive layer (for example, the AlN film 13) that is in contact with the surface opposite to the silicon oxide film 14 and the p-electrode 15 has been described. Instead, a compound containing any of aluminum, nitrogen, silicon, carbon, oxygen, zinc, titanium, and niobium may be used.

  In the above embodiment, the example in which AlN is used as the material of the heat conduction portion (for example, the AlN embedded portion 18) provided in the semiconductor substrate 1 has been described. However, instead of AlN, aluminum, nitrogen, silicon A compound containing any of carbon, oxygen, zinc, titanium, niobium, gold, silver, copper, platinum, titanium, chromium, molybdenum, tungsten, nickel, or any other metal or a combination thereof may be used. .

  In the above embodiment, the example in which the present invention is applied to a ridge waveguide type semiconductor optical device or a buried waveguide type semiconductor optical device has been described. However, the present invention is applied to a distributed feedback laser (DFB laser) in which a diffraction grating is formed. Of course, the present invention may be applied to optical elements such as the above.

[Example of application to optical modules]
An example in which the semiconductor optical device 100 according to the embodiment of the present invention (any one of 100A to C or another embodiment) is mounted on the optical module M is shown in FIG. As shown in FIG. 15, the optical module M includes a semiconductor optical device 100, a photodiode 101 that receives backward emitted light from the semiconductor optical device 100, a thermistor 102 that measures the temperature of the semiconductor optical device 100, a driver IC 103, and a driver. A signal line 104 for inputting data to the IC 103 and a power line 106 for supplying driving power to the driver IC 103 are provided. The forward outgoing light from the semiconductor optical device 100 becomes the optical output 105. In addition, as a result of evaluating the optical dynamic characteristics, this optical module M obtained a relaxation oscillation frequency of 26 GHz.

  Of course, the present invention is not limited to the above-described embodiments, and it goes without saying that various changes, modifications, and substitutions can be made by those skilled in the art having ordinary knowledge in this field.

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate, 2 Etching stop layer, 3 Buffer layer, 4 Cladding layer, 5 n-type InAlAs layer, 6 Strained multiple quantum well structure active layer, 7 p-type InAlAs layer, 8 Cladding layer, 10 contact layer, 11 Light guide region 12 ridge waveguide, 13 AlN film, 14 silicon oxide film, 15 p electrode, 16 pad electrode, 17 heat radiation electrode, 18 AlN buried portion, 19 n electrode, 20 heat radiation electrode, 21 wire, 22 solder, 23 submount Electrode, 24 submount, 25 AlN buried portion, M optical module, 100 (100A, 100B, 100C) semiconductor optical element, 101 photodiode, 102 thermistor, 103 driver IC, 104 signal line, 105 optical output, 106 power line.

Claims (12)

A semiconductor substrate;
An optical waveguide constituted by at least a part of a semiconductor laminate including a clad layer and an active layer laminated above the semiconductor substrate;
A heat conduction part formed of a material having a higher thermal conductivity than a material forming the semiconductor substrate, embedded in a groove formed at least under the optical waveguide and inside the semiconductor substrate. A semiconductor optical device. The semiconductor optical device according to claim 1,
An etching stop layer provided on the upper surface of the semiconductor substrate;
The groove formed in the semiconductor substrate is formed by etching from the lower surface of the semiconductor substrate to the etching stop layer. The semiconductor optical device according to claim 1, wherein
an n-electrode;
An upper surface of the heat conducting portion is in contact with the etching stop layer, and a lower surface of the heat conducting portion is in contact with the n electrode. The semiconductor optical device according to claim 1, wherein
An n-electrode formed to be in contact with a side surface of the groove and the etching stopper layer;
The side surface of the groove is formed to be vertical,
The heat conducting part is embedded in the groove after the n electrode is formed. A semiconductor optical device, wherein: A semiconductor optical device according to claim 1,
The heat conducting part is a compound containing any of aluminum, nitrogen, silicon, carbon, oxygen, zinc, titanium, niobium, gold, silver, copper, platinum, titanium, chromium, molybdenum, tungsten, and nickel. Or a combination of these materials. A semiconductor optical device, wherein: A semiconductor optical device according to any one of claims 1 to 5,
A semiconductor optical device, wherein a distance between the heat conducting portion and the active layer is 20 μm or less. The semiconductor optical device according to claim 1,
a p-electrode;
An insulating film provided on the lower surface of the p-electrode;
An insulating heat conducting portion formed of a material that is an insulating material and has a higher thermal conductivity than a material that forms the semiconductor laminated portion, between the insulating film and the semiconductor laminated portion; A semiconductor optical device. A semiconductor substrate;
An optical waveguide constituted by at least a part of a semiconductor laminate including a clad layer and an active layer laminated above the semiconductor substrate;
a p-electrode;
An insulating film provided on the lower surface of the p-electrode;
Between the insulating film and the semiconductor stacked portion, an insulating heat conductive portion formed of a material that is an insulating material and has a higher thermal conductivity than a material that forms the semiconductor stacked portion. A semiconductor optical device. The semiconductor optical device according to claim 7 or 8, wherein
At least a part of the insulating heat conducting portion is embedded in an active layer isolation trench formed to reduce the capacity of the active layer. A semiconductor optical device, wherein: A semiconductor optical device according to any one of claims 7 to 9,
An electrically insulated heat dissipating electrode provided on at least a part of the upper surface of the insulating heat conducting portion;
A support for supporting the semiconductor substrate;
The semiconductor optical device, further comprising: an electrode provided on the support portion and a wire connecting the heat dissipation electrode. A semiconductor optical device according to any one of claims 7 to 10,
The insulating heat conducting part is formed using a material made of any one of a compound containing aluminum, nitrogen, silicon, carbon, oxygen, zinc, titanium, or niobium, or a combination thereof. Semiconductor optical device. An optical module comprising the semiconductor optical device according to claim 1.

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