阅读说明：本技术 半导体光放大器、光输出装置以及距离测量装置 (Semiconductor optical amplifier, optical output device, and distance measuring device ) 是由 早川纯一朗 村上朱实 于 2019-06-11 设计创作，主要内容包括：本发明提供一种半导体光放大器、光输出装置以及距离测量装置。在使用分布式布拉格反射镜波导的半导体光放大器中,与不具有反射部的情况相比,增大预先规定的方向的光输出。半导体光放大器包含：光源部,所述光源部形成在基板上；以及光放大部,所述光放大部包括从光源部沿着基板的基板面朝向预先规定的方向延伸而形成的导电区域以及形成在导电区域的周围的非导电区域,所述光放大部对从光源部向预先规定的方向传播的传播光进行放大,并将放大后的传播光向与基板面交叉的射出方向射出,导电区域具有在从与所述基板面垂直的方向观察时将传播光向与预先规定的方向交叉的方向反射的反射部。(The invention provides a semiconductor optical amplifier, an optical output device and a distance measuring device. In a semiconductor optical amplifier using a distributed Bragg reflector waveguide, the optical output in a predetermined direction is increased as compared with the case where no reflection section is provided. The semiconductor optical amplifier includes: a light source section formed on a substrate; and a light amplification unit including a conductive region formed to extend from the light source unit in a predetermined direction along a substrate surface of the substrate, and a non-conductive region formed around the conductive region, the light amplification unit amplifying propagating light propagating from the light source unit in the predetermined direction and emitting the amplified propagating light in an emission direction intersecting the substrate surface, the conductive region including a reflection unit reflecting the propagating light in a direction intersecting the predetermined direction when viewed from a direction perpendicular to the substrate surface.)

1. A semiconductor optical amplifier, comprising:

a light source section formed on a substrate; and

a light amplification unit including a conductive region formed to extend from the light source unit in a predetermined direction along a substrate surface of the substrate and a non-conductive region formed around the conductive region, the light amplification unit amplifying propagating light propagating from the light source unit in the predetermined direction and emitting the amplified propagating light in an emission direction intersecting the substrate surface,

the conductive region has a reflecting portion that reflects the propagating light in a direction intersecting the predetermined direction when viewed from a direction perpendicular to the substrate surface.

2. The semiconductor optical amplifier according to claim 1,

the emission direction is a direction inclined in a predetermined direction.

3. The semiconductor optical amplifier according to claim 1 or 2,

the reflecting portion is an end face of the conductive region that is inclined at a predetermined angle with respect to the predetermined direction when viewed from a direction perpendicular to the substrate surface.

4. The semiconductor optical amplifier according to claim 3,

the predetermined angle is 5 degrees or more and 85 degrees or less.

5. The semiconductor optical amplifier according to claim 3 or 4,

the predetermined angle is an angle other than 45 degrees.

6. The semiconductor optical amplifier according to any one of claims 1 to 5,

the semiconductor optical amplifier further includes: a 1 st conductive type 1 st semiconductor multilayer film reflection mirror formed on the substrate; an active region on the 1 st semiconductor multilayer film mirror; and a 2 nd conductive type 2 nd semiconductor multilayer film reflecting mirror on the active region,

the conductive region is configured to contain the active region,

the non-conductive region is an oxidized region or an ion implanted region formed in a part of at least one of the 1 st semiconductor multilayer film reflection mirror and the 2 nd semiconductor multilayer film reflection mirror.

7. A light output device, comprising:

a semiconductor optical amplifier according to any one of claims 1 to 6; and

and a light-condensing unit that condenses light emitted from the semiconductor optical amplifier.

8. A distance measuring device, comprising:

a semiconductor optical amplifier according to any one of claims 1 to 6;

a light receiving unit that receives reflected light that is emitted from the semiconductor optical amplifier and reflected by an object to be measured; and

and a measuring unit that measures a distance to the object based on the reflected light received by the light receiving unit.

Technical Field

The present invention relates to a semiconductor optical amplifier, an optical output device, and a distance measuring device, and more particularly, to a semiconductor optical amplifier using a waveguide using a distributed bragg reflector, an optical output device using the semiconductor optical amplifier, and a distance measuring device.

Background

Patent document 1 discloses a light emitting element array having a plurality of semiconductor laminated structures, the semiconductor laminated structures including: a light emitting portion formed on a substrate; and a light amplification unit that extends from the light emission unit along the substrate surface of the substrate, the light amplification unit having a length in an extending direction that is longer than a length in the extending direction of the light emission unit, the light amplification unit amplifying light propagating from the light emission unit in the extending direction and emitting the amplified light from a light emission unit formed in the extending direction, the plurality of semiconductor laminated structures being arranged such that the extending directions of the respective light amplification units are substantially parallel to each other.

Disclosure of Invention

Problems to be solved by the invention

An object of the present invention is to provide a semiconductor optical amplifier using a distributed bragg reflector waveguide, which increases the light output in a predetermined direction compared to a case where a reflection unit that reflects propagating light propagating from a light source unit in a predetermined direction to a direction intersecting the predetermined direction is not provided.

Means for solving the problems

The semiconductor optical amplifier according to claim 1 includes: a light source section formed on a substrate; and a light amplification unit including a conductive region formed to extend from the light source unit in a predetermined direction along a substrate surface of the substrate, and a non-conductive region formed around the conductive region, the light amplification unit amplifying propagating light propagating from the light source unit in the predetermined direction and emitting the amplified propagating light in an emission direction intersecting the substrate surface, the conductive region including a reflection unit reflecting the propagating light in a direction intersecting the predetermined direction when viewed from a direction perpendicular to the substrate surface.

A semiconductor optical amplifier according to claim 2 is the semiconductor optical amplifier according to claim 1, wherein the emission direction is a direction inclined to a propagation direction of the propagation light.

A semiconductor optical amplifier according to claim 3 is the semiconductor optical amplifier according to claim 1 or 2, wherein the reflection portion is an end face of the conductive region, and the end face of the conductive region is inclined at a predetermined angle with respect to the predetermined direction when viewed from a direction perpendicular to the substrate surface.

A semiconductor optical amplifier according to claim 4 is the semiconductor optical amplifier according to claim 3, wherein the predetermined angle is 5 degrees or more and 85 degrees or less.

A semiconductor optical amplifier according to claim 5 is the semiconductor optical amplifier according to claim 3 or 4, wherein the predetermined angle is an angle other than 45 degrees.

A semiconductor optical amplifier according to claim 6 is the semiconductor optical amplifier according to any one of claims 1 to 5, further comprising: a 1 st conductive type 1 st semiconductor multilayer film reflection mirror formed on the substrate; an active region on the 1 st semiconductor multilayer film mirror; and a 2 nd conductive type 2 nd semiconductor multilayer film reflection mirror on the active region, the conductive region is configured to include the active region, and the non-conductive region is an oxidized region or an ion implanted region formed in a part of at least one of the 1 st semiconductor multilayer film reflection mirror and the 2 nd semiconductor multilayer film reflection mirror.

An optical output device according to claim 7 includes: the semiconductor optical amplifier according to any one of claims 1 to 6; and a light-condensing unit that condenses light emitted from the semiconductor optical amplifier.

A distance measuring device according to claim 8 includes: the semiconductor optical amplifier according to any one of claims 1 to 6; a light receiving unit that receives reflected light that is emitted from the semiconductor optical amplifier and reflected by an object to be measured; and a measuring unit that measures a distance to the object to be measured based on the reflected light received by the light receiving unit.

Effects of the invention

According to the 1 st, 7 th and 8 th aspects, the following effects are obtained: provided is a semiconductor optical amplifier using a distributed Bragg reflector waveguide, wherein the optical output in a predetermined direction is increased compared with a case where a reflection unit for reflecting propagating light propagating from a light source unit in a predetermined direction to a direction crossing the predetermined direction is not provided.

According to the 2 nd mode, the following effects are obtained: the light is emitted in a direction away from the light source, as compared with a case where the emission direction is inclined in a direction opposite to the propagation direction of the light.

According to the 3 rd mode, the following effects are obtained: provided is a semiconductor optical amplifier, which can increase the light output in a predetermined direction compared with the case that a reflecting part is not inclined to the predetermined direction when viewed from the direction vertical to the substrate surface.

According to the 4 th mode, the following effects are obtained: the light output in the predetermined direction is increased more than in the case where the predetermined angle is less than 5 degrees or exceeds 85 degrees.

According to the 5 th mode, the following effects are obtained: the light output in the predetermined direction is further increased as compared with the case where the predetermined angle is 45 degrees.

According to the 6 th mode, the following effects are obtained: in a semiconductor optical amplifier including a 1 st semiconductor multilayer film mirror, an active region, and a 2 nd semiconductor multilayer film mirror formed on a substrate, light output in a predetermined direction is increased.

Drawings

Fig. 1 shows an example of the structure of a semiconductor optical amplifier according to embodiment 1, where fig. 1 (a) is a plan view and fig. 1 (b) is a cross-sectional view.

Fig. 2 (a) is a plan view showing reflection at the reflection portion of the semiconductor optical amplifier according to the comparative example, fig. 2 (b) is a plan view showing reflection at the reflection portion of the semiconductor optical amplifier according to embodiment 1, and fig. 2 (c) is a plan view showing reflection when the inclination angle of the reflection portion is 45 degrees.

Fig. 3(a) is a graph showing the light output characteristics of the semiconductor optical amplifier according to the comparative example, fig. 3 (b) is a graph showing the light output characteristics of the semiconductor optical amplifier according to embodiment 1, and fig. 3 (c) is a graph showing the light output characteristics when the inclination angle of the reflection portion is 45 degrees.

Fig. 4 (a) and 4 (b) are diagrams showing modifications of the reflection unit of the semiconductor optical amplifier according to embodiment 1.

Fig. 5 shows an optical processing device and a distance measuring device according to embodiment 2, where fig. 5 (a) is a block diagram showing an example of the optical processing device and fig. 5 (b) is a block diagram showing an example of the distance measuring device.

Fig. 6 shows a structure of a semiconductor optical amplifier according to a comparative example, where fig. 6 (a) is a plan view and fig. 6 (b) is a cross-sectional view.

Description of the symbols

10 semiconductor optical amplifier

18P electrode

30 base plate

32 lower DBR

34 active region

36 upper DBR

40N electrode

50 light amplification part

52 optical coupling part

54. 54A, 54B, 54C, 54D reflection parts

56 oxidation front

58 conductive region

60 non-conductive area

64 end portion

66 inclined part

70 light processing device

71 semiconductor optical amplifier

72 lens

90 distance measuring device

91 semiconductor optical amplifier

92 distance measuring sensor

93 measurement part

100 semiconductor optical amplifier

Lf positive output

Lr reverse output

Po light output

Pt projection light

Pr received light

Angle of inclination theta

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[ embodiment 1 ]

The semiconductor optical amplifier 10 according to the present embodiment will be described with reference to fig. 1 to 4. Fig. 1 (a) is a plan view of the semiconductor optical amplifier 10, and fig. 1 (b) is a cross-sectional view taken along the line a-a' shown in fig. 1 (a). As shown in fig. 1, a Semiconductor Optical Amplifier (SOA) 10 has an Optical amplifying section 50, a reflecting section 54, and an Optical coupling section 52.

The optical amplification unit 50 has a function of amplifying and emitting light (seed light) coupled to the optical coupling unit 52. The optical coupling section 52 is an example of a light source section. An example of the optical amplification unit 50 according to the present embodiment is a surface emitting optical amplification unit using a GaAs-series distributed Bragg reflector waveguide (hereinafter, "dbr (distributed Bragg reflector) waveguide"). That is, the optical amplification section 50 includes the N-electrode 40 formed on the rear surface of the substrate 30, the lower DBR32 formed on the substrate 30, the active region 34, the upper DBR36, the non-conductive region 60, the conductive region 58, and the P-electrode 18.

In the present embodiment, the substrate 30 is an N-type GaAs substrate, and the N-electrode 40 is provided on the back surface of the substrate 30. On the other hand, the lower DBR32 of the present embodiment is n-type, and the upper DBR36 is p-type. When the semiconductor optical amplifier 10 is driven, the positive electrode of the driving power supply is applied to the P-electrode 18, the negative electrode is applied to the N-electrode 40, and a driving current flows from the P-electrode 18 to the N-electrode 40. However, the polarities of the substrate 30, the lower DBR32, and the upper DBR36 are not limited to this, and they may be reversed, that is, the substrate 30 may be a p-type GaAs substrate, the lower DBR32 may be a p-type, and the upper DBR36 may be an n-type.

The lower DBR32 is paired with the upper DBR36 described below, and constitutes a resonator contributing to light emission in the semiconductor optical amplifier 10. The lower DBR32 is a multilayer film mirror configured by alternately and repeatedly laminating two semiconductor layers, each having a film thickness of 0.25 λ/n and a refractive index different from each other, when the oscillation wavelength of the semiconductor optical amplifier 10 is λ and the refractive index of the medium (semiconductor layer) is n. Specifically, the lower DBR32 is made of Al_0.90Ga_0.1An n-type low refractive index layer of As and Al_0.2Ga_0.8The n-type high refractive index layer made of As is alternately and repeatedly laminated.

The active region 34 according to the present embodiment may include, for example, a lower spacer layer, a quantum well active region, and an upper spacer layer (not shown). The quantum well active region according to the present embodiment may include, for example, four layers of Al_0.3Ga_0.7Barrier layers made of As and a three-layer quantum well layer made of GaAs disposed between the barrier layers. The lower spacer layer and the upper spacer layer are respectively disposed between the quantum well active region and the lower DBR32 and between the quantum well active region and the upper DBR36, thereby having a tuned resonanceThe length of the device and also as a cladding (clad) for confining the carriers.

The non-conductive region 60 and the conductive region 58 disposed on the active region 34 are P-type oxide confinement layers, i.e., current confinement layers. That is, the non-conductive regions 60 correspond to oxidized regions, and the conductive regions 58 correspond to non-oxidized regions. In this embodiment, one layer of the multilayer film constituting the upper DBR36 is oxidized to form the non-conductive region 60 (oxidized region), and the region other than the one layer of the non-conductive region 60 becomes the non-oxidized conductive region 58 (non-oxidized region). The current flowing from the P-electrode 18 toward the N-electrode 40 is narrowed by the conductive region 58. In addition, although the embodiment has been described by exemplifying the form in which the non-conductive region 60 (oxidized region) is formed in one layer of the upper DBR36, the present invention is not limited to this, and may be formed in a plurality of layers in the upper DBR36 or may be formed in the lower DBR 32.

In the semiconductor optical amplifier 10 according to the present embodiment, the interface between the conductive region 58 and the non-conductive region 60 (hereinafter referred to as "oxidation front" 56) extends along the propagation direction of the propagation light introduced from the optical coupling section 52 and propagating through the DBR waveguide (direction from the left side to the right side of the sheet of fig. 1), and a reflection section 54 that reflects the propagation light is formed on the end surface of the oxidation front 56 on the side opposite to the optical coupling section 52. The reflection portion 54 according to the present embodiment is configured by the end face of the oxidation front 56, as shown in fig. 1 (a), the end face of the oxidation front 56 is inclined in a direction intersecting the traveling direction of the propagating light in a plan view (when viewed from a direction perpendicular to the substrate 30). The non-conductive region 60 is formed by oxidizing the semiconductor optical amplifier formed in a mesa shape at least up to the lower portion of the upper DBR from the periphery in the manufacturing process of the semiconductor optical amplifier 10. Thus, the outer shape of the semiconductor optical amplifier 10 is provided with a portion conforming to the outer shape of the reflection portion 54, that is, the inclined portion 66 along the reflection portion 54. The operation and the like of the reflection unit 54 will be described in detail later. In addition, although the embodiment has been described by exemplifying the embodiment in which the nonconductive region 60 is formed by oxidation, the present invention is not limited to this, and may be formed by ion implantation or the like, for example.

The upper DBR36 is a multilayer film mirror formed by alternately and repeatedly laminating two semiconductor layers, each having a film thickness of 0.25 λ/n and having refractive indices different from each other. Specifically, the upper DBR36 is made of Al_0.90Ga_0.1A p-type low refractive index layer of As and Al_0.2Ga_0.8The p-type high refractive index layers made of As are alternately and repeatedly stacked.

The optical coupling unit 52 according to the present embodiment is a unit for coupling a light source that generates input light (seed light) to be input to the semiconductor optical amplifier 10. In the present embodiment, input light is propagated from an external light source, not shown, through an optical fiber, the output end of the optical fiber is coupled to an optical coupling section 52 functioning as a light source section of the semiconductor optical amplifier 10, and the input light is introduced into the DBR waveguide. As the external light source, for example, a surface Emitting Laser (VCSEL) is used. In addition, although the present embodiment has been described by exemplifying the light source for introducing seed light from the outside, the present invention is not limited to this, and a light emitting element such as a VCSEL that functions as a light source portion may be formed integrally with the semiconductor optical amplifier 10 in a region where the optical coupling portion 52 is arranged of the semiconductor optical amplifier 10. In the present embodiment, the seed light is input and the current is injected into the semiconductor optical amplifier 10 to amplify the seed light and output, but the seed light may be input to a position on the longer wavelength side than the peak wavelength of the wavelength spectrum of the gain of the active region 34. By doing so, the mode controllability is improved. The seed light is preferably set to a wavelength having an intensity of one tenth or less of the peak intensity of the gain.

Here, the DBR waveguide according to the present embodiment will be described in more detail. The excitation light introduced from the optical coupling section 52 propagates in a propagation direction from the left side to the right side of the paper. At this time, as shown in fig. 1 (b), the propagating light propagates mainly in the lower DBR32, the active region 34, the conductive region 58, and the upper DBR36 with a predetermined distribution. Thus, a "DBR waveguide" encompasses these portions. In the present embodiment, a reflection portion 54 is formed at an end portion (oxidation front 56) of a conductive region 58 that is a part of the DBR waveguide, and propagating light is reflected by the reflection portion 54. That is, since the non-conductive region 60 is formed by oxidizing the conductive region 58, the refractive index of the non-conductive region 60 is lower than that of the conductive region. Therefore, the equivalent refractive index of the region of the DBR waveguide including the conductive region 58 is higher than the equivalent refractive index of the DBR waveguide including the non-conductive region 60, and the propagating light is reflected by the reflective portion 54 which is the interface (oxidation front 56) of the conductive region 58 and the non-conductive region 60.

However, a semiconductor optical amplifier using a DBR waveguide is configured by a pair of DBRs provided on a semiconductor substrate, an active region located between the pair of DBRs, and a resonator spacer layer. The region sandwiched by the DBRs functions as an optical waveguide, and light input into the DBR waveguide is reflected a plurality of times in an oblique direction while propagating slowly. At this time, when a current is injected into the active region 34 through the P-electrode 18 and the N-electrode 40 provided on both sides of the DBR, the input light is amplified and an amplified light beam (hereinafter referred to as "forward output Lf") is output in an oblique forward direction which is a direction intersecting the substrate surface and which is oblique forward to the propagation direction of the DBR waveguide through which the light propagates. On the other hand, output light reflected by a boundary portion between the input side and the opposite side and output in an oblique rear direction which is a direction intersecting the substrate surface and which is inclined rearward in the propagation direction of the DBR waveguide in which the light propagates is referred to as "reverse output Lr".

That is, the region of the semiconductor optical amplifier 10 where the P-electrode 18 and the N-electrode 40 are provided (the region sandwiched between the P-electrode 18 and the N-electrode 40) functions as both an optical waveguide and an optical amplification unit, and amplified light is emitted in a direction intersecting the surface of the substrate 30. That is, the semiconductor optical amplifier using the DBR waveguide constitutes a surface emitting semiconductor optical amplifier. On the other hand, light is input to the amplifying section by: a part of the DBR is removed by etching, a light incident portion (optical coupling portion 52) with reduced reflectance is formed, and external light is obliquely incident and coupled, or light emitted from a light source (light emitting portion) is laterally integrated as a part of a semiconductor optical amplifier, and light emitted to a light amplification portion is propagated.

As described above, in the semiconductor optical amplifier using the DBR waveguide such as the semiconductor optical amplifier 10, output light including the reverse output Lr having an emission direction different from the forward output Lf is output in addition to the forward output Lf. Here, it is inconvenient that the directions of the optical outputs of the semiconductor optical amplifier 10 are two, and it is desirable to integrate them into at least one of them, but in this case, it is preferable to integrate them into the forward output Lf. This is because, in the case of the reverse output Lr, for example, an optical system receiving the reverse output Lr and an optical system coupled to the optical coupling section 52 easily cause disturbance in arrangement. On the other hand, in the case of the forward output Lf, since light is emitted in a direction away from the light source, for example, disturbance of the optical system is less likely to occur.

However, if light coupled and input to the optical coupling section 52 or light input from the integrated light emitting section propagates through a region sandwiched by the DBR pair and return light is generated by reflection at a boundary section (reflection section 54) between the input side and the opposite side, the operation of the semiconductor optical amplifier becomes unstable, and there is a problem that stable amplified light output cannot be obtained in the forward direction.

The above problem will be described in more detail with reference to fig. 6. Fig. 6 shows a semiconductor optical amplifier 100 according to a comparative example, which has an optical amplification unit 50 and an optical coupling unit 52, similarly to the semiconductor optical amplifier 10 shown in fig. 1. Fig. 6 (B) is a sectional view taken along the line B-B' shown in fig. 6 (a). In the following description, the same components as those of the semiconductor optical amplifier 10 are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in fig. 6 (a), the semiconductor optical amplifier 100 has a conductive region 58 and a non-conductive region 60 which are bordered by the oxidation front 56. An end 64 of the conductive region 58 on the side opposite to the optical coupling portion 52 is perpendicular to the propagation direction of the propagating light. That is, the end 64 is not inclined with respect to the propagation direction of the propagating light.

In the semiconductor optical amplifier 100 having the above configuration, the input light incident from the optical coupling portion 52 is amplified while propagating in the direction of the end portion 64, and is output as the forward output Lf in a direction inclined forward and toward the propagation direction. On the other hand, the propagating light reflected by the end portion 64 returns as return light in the direction of the optical coupling portion 52, and outputs a backward output Lr in a direction inclined rearward and toward the propagating direction. In the case of the semiconductor optical amplifier 100, as shown in fig. 6 (b), the reverse output Lr is output over the entire DBR waveguide. Therefore, in the semiconductor optical amplifier 100 according to the comparative example, the forward output Lf is reduced because the propagating light and the return light coexist and the light energy is distributed to the reverse output Lr. This is a mechanism for generating the above-described problem.

In view of the above problem, in the present embodiment, a reflection portion that reflects the propagation light of the DBR waveguide in the semiconductor optical amplifier in a direction intersecting the propagation direction is provided at an end portion of the DBR waveguide. Accordingly, since the return light is attenuated during propagation and interference between the propagation light and the return light is suppressed, it is possible to provide a surface-emitting semiconductor optical amplifier in which the light output (forward output Lf) in a predetermined direction is increased as compared with the case where such a reflection unit is not provided.

Referring again to fig. 1 (a), since the reflection portion 54 of the semiconductor optical amplifier 10 is inclined in the direction intersecting the propagation direction of the propagating light, even if most of the propagating light is reflected by the reflection portion 54, it does not return in the direction of the optical coupling portion 52, and attenuates and disappears in the middle as shown in fig. 1 (b). As a result, since the propagation light becomes dominant, the light energy distributed to the reverse output Lr decreases, and the light energy diverted to the forward output Lf increases, that is, the forward output Lf increases.

Next, the operation of the semiconductor optical amplifier 10 to achieve the above-described effects will be described in more detail with reference to fig. 2 and 3. Fig. 2 is a diagram showing the difference between the propagating light (traveling wave) and the return light (reflected wave) when the inclination angle θ of the end of the conductive region is different. In the present embodiment, the inclination angle θ of the end is defined by an angle measured from a direction perpendicular to the propagation direction as shown in fig. 2. That is, fig. 2 (a) shows the reflection unit 54A when the inclination angle θ is 0 degrees, fig. 2 (B) shows the reflection unit 54 according to the present embodiment when the inclination angle θ is 15 degrees, and fig. 2 (c) shows the reflection unit 54B when the inclination angle θ is 45 degrees. Here, the reflection portion 54A shown in fig. 2 (a) corresponds to the end portion 64 of the semiconductor optical amplifier 100 shown in fig. 6. The optical paths of the propagation light and the return light shown in fig. 2 only show the optical paths of the main components.

As shown in fig. 2 (a), when the inclination angle θ is 0 degrees, the propagating light reflected by the reflection portion 54A returns as return light in the direction of the optical coupling portion 52 along the same optical path as the incident optical path. As shown in fig. 2 (c), when the inclination angle θ is 45 degrees, the propagating light reflected by the reflection unit 54B is once reflected in the direction perpendicular to the direction of the propagating light, but is again reflected by the reflection unit 54B, and returns as return light in the direction of the optical coupling unit 52 along the same optical path as the incident optical path. On the other hand, when the inclination angle θ is 15 degrees, the reflected light is reflected by the reflection portion 54 and then reflected between the oxidation front 56. In the process of this reflection, the return light disappears halfway as shown in fig. 1 (b), and therefore the reverse output Lr decreases. Thus, in the semiconductor optical amplifier 10 according to the present embodiment, the output light can be concentrated on the forward output Lf.

Fig. 3 shows the light output of the semiconductor optical amplifier having the structure shown in each of fig. 2 as the reflection unit, fig. 3(a) shows the forward output Lf and the reverse output Lr at an inclination angle θ of 0 degrees, fig. 3 (b) shows the forward output Lf and the reverse output Lr at an inclination angle θ of 15 degrees, and fig. 3 (c) shows the forward output Lf and the reverse output Lr at an inclination angle θ of 45 degrees. The forward output Lf and the reverse output Lr are measured by two light receiving elements arranged in the direction of the respective light output.

As shown in fig. 3(a), when the inclination angle θ is 0 degrees, most of the light output is the reverse output Lr, and only a small amount of the forward output Lf is output. As shown in fig. 3 (c), when the inclination angle θ is 45 degrees, most of the light output is the reverse output Lr, and only a small amount of the forward output Lf is output. On the other hand, when the inclination angle is 15 degrees, most of the forward output Lf is generated, and the reverse output Lr is hardly generated. The inclination angle θ in the present embodiment is not particularly limited, but is preferably 5 degrees or more and 85 degrees or less. The inclination angle θ is preferably an angle other than 45 degrees.

Here, the shape of the reflection portion 54 constituting the end portion of the conductive region 58 will be described with reference to fig. 4. In fig. 1 (a), the description has been given by taking an example in which the reflection portion 54 is a plane of the oxidation front 56 in the direction intersecting the propagation direction, but the present invention is not limited to this. For example, as shown in fig. 4 (a), the reflecting portion 54C may be provided to have a reflecting surface inclined with respect to the propagation direction in a part of the end portion of the conductive region 58. Alternatively, as shown in fig. 4 (b), the end of the conductive region 58 may be provided with a reflection portion 54D having two inclined surfaces inclined in directions opposite to each other with respect to the propagation direction. The same effect as that of the reflection portion 54 is obtained also in the reflection portion 54C or 54D.

[ 2 nd embodiment ]

Next, the optical output device and the distance measuring device according to the present embodiment will be described with reference to fig. 5. Fig. 5 (a) shows a block diagram of the optical processing device 70 as an example of the optical output device according to the present invention, and fig. 5 (b) shows a block diagram of the distance measuring device 90.

As shown in fig. 5 (a), the optical processing device 70 includes a semiconductor optical amplifier 71 and a condensing lens 72. The semiconductor optical amplifier 71 is, for example, the semiconductor optical amplifier 10 according to the above embodiment. As shown in fig. 5 (a), the light emitted from the semiconductor optical amplifier 71 is condensed by the lens 72 and is irradiated to the object OB1 as output light Po to perform processing on the object OB 1.

On the other hand, as shown in fig. 5 (b), the distance measuring device 90 includes a semiconductor optical amplifier 91, a distance measuring sensor 92, and a measuring unit 93. The semiconductor optical amplifier 91 is, for example, the semiconductor optical amplifier 10 according to the above embodiment. The distance measuring sensor 92 is composed of a light receiving element such as a photodiode, for example, and the measuring unit 93 is mainly composed of a semiconductor element such as a CPU or an ASIC.

In the distance measuring device 90, the projected light Pt emitted from the semiconductor optical amplifier 91 is irradiated to an object to be measured OB2 (e.g., a person or an object), and the reflected light reflected by the object to be measured OB2 is input to the distance measuring sensor 92 as received light Pr. The received light Pr input to the distance measuring sensor 92 is converted into an electric signal, and a predetermined arithmetic process is performed in the measuring unit 93 based on the electric signal, for example, a distance between the distance measuring device 90 and the object OB2 is measured.

The foregoing description of the exemplary embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.