WO2009119131A1

WO2009119131A1 - Semiconductor light-emitting element and method for fabricating the element

Info

Publication number: WO2009119131A1
Application number: PCT/JP2009/050281
Authority: WO
Inventors: 昌輝大矢
Original assignee: 日本電気株式会社
Priority date: 2008-03-28
Filing date: 2009-01-13
Publication date: 2009-10-01

Abstract

There is provided an active MMI type semiconductor laser of an inner stripe type, which has a preferable beam shape and in which radiation light is removed. The semiconductor light-emitting element comprises a planar-type active layer, a current blocking layer for suppressing current flowing into the active layer, and an inner stripe-type active waveguide constituted by a stripe-shaped opening of the current blocking layer. The active waveguide includes an active multi-mode interference waveguide, a first single mode waveguide extended from the active multi-mode interference waveguide to an emission end, and a second single mode waveguide extended from the active multi-mode interference waveguide to the opposite side of the first single mode waveguide. The length of the first single mode waveguide is longer than the length of the second single mode waveguide.

Description

Semiconductor light emitting device and manufacturing method thereof

The present invention relates to a semiconductor light emitting device, and more particularly to a high output semiconductor light emitting device.

Semiconductor lasers are generally required to achieve both high light output and single transverse mode operation. For example, in a semiconductor laser for an optical disk such as a GaN blue-violet semiconductor laser for a next-generation DVD light source or an AlGaInP red semiconductor laser for a DVD light source, a high output operation is performed for high-speed recording, and a single horizontal operation is performed for high-density recording. Mode operation is required. In addition, when a GaN-based semiconductor laser or an AlGaInP-based semiconductor laser is used as a light source for laser display, a high output operation is required for large screen projection, and a single mode operation is desirable for downsizing the optical system. In addition, an InP long-wave semiconductor laser for optical fiber communication also requires both high output operation and single transverse mode operation for high-speed and large-capacity communication.

In ordinary semiconductor lasers, it is necessary to narrow the waveguide width in order to realize single transverse mode operation. Therefore, the element resistance increases, the heat generation of the element increases, and the light output decreases. On the other hand, for example, Patent Document 1 proposes an active MMI type semiconductor laser structure using an active multi-mode interference (MMI) waveguide. In the active MMI type semiconductor laser, the active MMI waveguide is used as a main light emitting region, so that the element resistance can be reduced by expanding the active layer area. At the same time, by providing a single mode active waveguide at the light exit end, it is possible to achieve both high output operation and single transverse mode operation.

On the other hand, the active MMI type semiconductor laser has a problem that the shape of the beam emitted from the semiconductor laser is disturbed due to the light (radiated light) emitted as non-guided light from the active MMI waveguide. On the other hand, for example, in an InP-based buried heterostructure (BH) active MMI type semiconductor laser disclosed in Patent Document 2, a recess or a light absorber is provided for removing emitted light. .

FIG. 9 is a plan view of the active MMI type semiconductor laser described in FIG. 13 of Patent Document 2. 10 is FIG. 14 of Patent Document 2 and is a cross-sectional view taken along the line XX of FIG. 11 is FIG. 15 of Patent Document 2 and is a cross-sectional view taken along the line XI-XI of FIG. As shown in FIG. 9, the active MMI semiconductor laser described in Patent Document 2 includes an active fundamental mode waveguide 41 and an active MMI waveguide 42, and is provided at each light emitting end of the active fundamental mode waveguide 41. A light absorber 62 is formed. 10 and 11, an n-type InP substrate 51, an n-type InP buffer layer 52, an InGaAsP active layer 53, a p-type InP first cladding layer 54, a p-type InP current blocking layer 55, an n-type InP. A current blocking layer 56, a p-type InP second cladding layer 57, and a p-type InGaAs contact layer 58 are formed, and light absorbers 62 are formed on both sides of the active fundamental mode waveguide 41.

The first feature of this semiconductor laser is that a part of the active waveguide is composed of the active MMI waveguide 42. Thereby, the area of the main excitation region (region where gain is generated) can be expanded without changing the element length. At the same time, single transverse mode light can be obtained at the input and output ends of the active MMI waveguide 42. Therefore, the single transverse mode light output can be greatly improved. This active MMI type semiconductor laser cannot obtain single transverse mode light when, for example, an ordinary multimode waveguide is used instead of the active MMI waveguide 42. Further, when a passive MMI waveguide is used instead of the active MMI waveguide 42, it does not contribute to the area expansion of the main excitation region. In these respects, they are greatly different from ordinary semiconductor lasers.

The second feature is that a structure for removing emitted light is provided. Radiant light hardly occurs in an ideal active MMI waveguide. However, in an actual semiconductor laser, part of the guided light is not self-imaged at the input / output end of the active MMI waveguide 42 due to manufacturing errors. Therefore, it is radiated out of the waveguide as non-guided light, and the output beam shape is disturbed. In Patent Document 2, a light absorber 62 is provided on the side of the active fundamental mode waveguide 41 to remove the emitted light and improve the beam shape. Non-patent document 1 will be described later.
Japanese Patent No. 3244115 Japanese Patent No. 3329765 Lucas B. Soldano, 1 other, "Optical Multi-Mode Interference Devices Based on Self-Imaging: Principles and Applications", Journal of Lightwave Technology, 1995, Vol. 13, no. 4, pages 615-627

In order to produce the synchrotron radiation removing means of Patent Document 2, it is necessary to etch away a part of the active layer. As disclosed in Patent Document 2, this is possible with an InP-based semiconductor laser. On the other hand, in the GaN-based semiconductor laser and the AlGaInP-based semiconductor laser, a part of the active layer cannot be removed by etching from the viewpoint of element reliability caused by a problem inherent in the material system. Therefore, when the active MMI structure is applied to a semiconductor laser having a so-called planar type active layer, such as a GaN-based semiconductor laser or an AlGaInP-based semiconductor laser, in which the active layer has a continuous shape in the horizontal direction, a synchrotron radiation removing means is provided I could not. Therefore, the deterioration of the beam shape due to the emitted light is inevitable.

Also, the active MMI type semiconductor laser disclosed in Patent Document 2 has no mechanism for guiding the emitted light, and the emitted light propagates while diffusing both in the horizontal direction and in the vertical direction. Therefore, the radiated light component diffused in the horizontal direction can be removed by the radiated light removing means, but the radiated light component diffused in the vertical direction cannot be removed. Therefore, there is a drawback that the effect of removing the emitted light is low.

It is an object of the present invention to provide an inner stripe type active MMI type semiconductor laser in which the emitted light is removed and the beam shape is good.

The semiconductor light emitting device according to the present invention is
A planar active layer;
A current blocking layer for constricting a current flowing into the active layer;
An inner stripe type active waveguide constituted by a stripe-shaped opening formed in the current blocking layer,
The active waveguide is
An active multimode interference waveguide;
A first single mode waveguide extending from the active multimode interference waveguide to the exit end;
A second single mode waveguide extending from the active multimode interference waveguide opposite to the first single mode waveguide;
The length of the first single mode waveguide is longer than the length of the second single mode waveguide.

According to the present invention, it is possible to provide an inner stripe type active MMI type semiconductor laser in which the emitted light is removed and the beam shape is good.

1 is a plan view of a waveguide of a semiconductor laser according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along the line II-II in FIG. FIG. 3 is a sectional view taken along line III-III in FIG. It is a beam propagation calculation result in the semiconductor laser for a comparison. It is a far-field image calculation result in the semiconductor laser for a comparison. It is a beam propagation calculation result in the semiconductor laser which concerns on embodiment. It is a far-field image calculation result in the semiconductor laser which concerns on embodiment. 1 is a detailed cross-sectional view of a semiconductor laser according to an embodiment. FIG. 14 is a plan view of the semiconductor laser described in FIG. 13 of Patent Document 2. FIG. 10 is a sectional view taken along line XX in FIG. 9. FIG. 10 is a sectional view taken along line XI-XI in FIG. 9.

Explanation of symbols

101 n-type substrate 102 n-type buffer layer 103 n-type cladding layer 104 n-side optical confinement layer 105 planar active layer 106 cap layer 107 p-side optical confinement layer 108 current blocking layer 109 waveguide 109a first active fundamental mode waveguide 109b Active MMI waveguide 109c Second active fundamental mode waveguide 110 p-type cladding layer 111 p-type contact layer 112 p-side electrode 113 n-side electrode

Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

Embodiment 1
FIG. 1 is a plan view of a waveguide of a semiconductor laser according to the first embodiment of the present invention. As shown in FIG. 1, the waveguide 109 of the active MMI semiconductor laser according to the first embodiment includes first and second active

fundamental mode waveguides

109a and 109c and an active MMI waveguide 109b. A current blocking layer 108 is formed around the waveguide 109. The + z direction is defined as the front (the main light emission side).

2 and 3 are sectional views taken along lines II-II and III-III in FIG. As shown in FIGS. 2 and 3, the active MMI semiconductor laser according to the present embodiment includes an n-type cladding layer 103, an n-side optical confinement layer 104, a planar active layer 105, a p-side optical confinement layer 107, a current. A blocking layer 108, a p-type cladding layer 110, and an active waveguide 109 having an inner stripe structure are provided. Here, the current blocking layer 108 controls the current distribution in the horizontal direction in the active layer 105 by blocking currents other than the active waveguide 109. At the same time, the light distribution in the horizontal direction is controlled by giving a refractive index difference in the horizontal direction. 2 and 3 are conceptual diagrams only, and the substrate and electrodes are omitted.

In the semiconductor laser having such a planar type active layer 105, the current I spreads outside the

active waveguides

109a and 109b as shown by broken line arrows in FIGS. 2 and 3, so that the vicinity of the

active waveguides

109a and 109b. In the active layer 105, light propagates without being absorbed. However, the current density decreases as the distance from the

active waveguides

109a and 109b increases. Therefore, light is attenuated as it propagates in the active layer 105 sufficiently away from the

active waveguides

109a and 109b, and functions as a light absorption region 105a. Here, if the light emitted from the active MMI waveguide 109b without being guided to the first active fundamental mode waveguide 109a located on the + z side, that is, the emission side is sufficiently attenuated in the light absorption region 105a, the emitted light Can be effectively removed. Therefore, the length of the first active fundamental mode waveguide 109a is made longer than the length of the second active fundamental mode waveguide 109c located on the opposite side via the active MMI waveguide 109b.

However, the length of the first active fundamental mode waveguide 109a cannot be increased without limitation. The reason is that if the length of the first active fundamental mode waveguide 109a is increased, the total length of the active waveguide 109 is increased, leading to deterioration in device characteristics such as an increase in operating current and an increase in cost such as increase in device dimensions. Because. Thus, in order to determine the length of the active waveguide 109, it is necessary to consider other aspects than the removal of the emitted light. Therefore, as shown in FIG. 1, the length of the second active fundamental mode waveguide 109c is shortened by the length of the first active fundamental mode waveguide 109a. Thereby, the first active fundamental mode waveguide 109a can be lengthened without changing the overall length of the active waveguide 109. Therefore, the radiation removal effect can be enhanced without increasing the operating current or increasing the element size.

Furthermore, the planar type active layer 105 has a continuous shape in the horizontal direction. Therefore, it performs a light guide function in the vertical direction with respect to the emitted light, and the emitted light propagates along the active layer 105 toward the light absorption region 105a without diffusing in the vertical direction. Therefore, all components of the emitted light can be reliably guided to the light absorption region 105a, and the effect of removing the emitted light can be greatly enhanced.

Further, since all the non-guided light that is not self-imaged at the input / output end of the active MMI waveguide 109b is guided to the light absorption region 105a, any radiated light can be removed. For example, when the active MMI waveguide 109b has a manufacturing error, not only the radiation generated with respect to the fundamental mode light but also the active MMI waveguide 109b is manufactured so that the self-imaging of the odd mode light is not allowed. It is also possible to remove the emitted light generated with respect to the mode light.

Next, the results of verifying the effect of the present invention by the beam propagation method (BPM) will be shown. FIG. 4 shows the result of calculating the intensity distribution of light propagating in the + z direction for a comparative active MMI semiconductor laser. The comparative active MMI type semiconductor laser has an active waveguide 9 including a first active fundamental mode waveguide 9a, a second active fundamental mode waveguide 9c, and an active MMI waveguide 9b. Here, the length of the first active fundamental mode waveguide 9a is equal to the length of the second active fundamental mode waveguide 9c. Light emitted from the active MMI waveguide 9 b without being guided to the first active waveguide 9 a reaches the front end of the active waveguide 9. FIG. 5 is a calculation result of a far-field image of the beam emitted from the front end of the active waveguide 9, and the beam shape is disturbed by the influence of the radiated light.

On the other hand, FIG. 6 shows the result of calculating the intensity distribution of light propagating in the + z direction for the active MMI semiconductor laser according to the present embodiment. The active MMI semiconductor laser according to the present embodiment has an active waveguide 109 including a first active fundamental mode waveguide 109a, a second active fundamental mode waveguide 109c, and an active MMI waveguide 109b. Here, the length of the first active fundamental mode waveguide 109a is longer than the length of the second active fundamental mode waveguide 109c. Increasing the length of the first active fundamental mode waveguide 109a increases the attenuation of light emitted without being guided from the active MMI waveguide 109b to the first active fundamental mode waveguide 109a. Little emitted light appears at the front end of the waveguide 109. FIG. 7 shows the calculation result of the far-field image of the beam emitted from the front end of the active waveguide 109. Since the emitted beam contains almost no radiation component, a good beam shape can be obtained. Here, the second active fundamental mode waveguide 109c is shortened by the length of the first active fundamental mode waveguide 109a. Therefore, the total length of the active waveguide 109 is equal to the total length of the active waveguide 9 in FIG. Therefore, it is possible to enhance only the effect of removing the emitted light without causing an increase in operating current or an increase in element size.

FIG. 8 is a more detailed view of FIG. On the n-type substrate 101, an n-type buffer layer 102, an n-type cladding layer 103, an n-side optical confinement layer 104, a planar active layer 105, a cap layer 106, a p-side optical confinement layer 107, and a current blocking layer 108 are provided. They are stacked in this order. The current blocking layer 108 has an opening removed in a stripe shape, and this opening constitutes an active fundamental mode waveguide 109a. A p-type cladding layer 110 and a p-type contact layer 111 are stacked in this order on the current blocking layer 108 and the active fundamental mode waveguide 109a which is an opening. A p-side electrode 112 is provided on the upper surface of the p-type contact layer 111, and an n-side electrode 113 is provided on the lower surface of the n-type substrate 101.

The n-type substrate 101 is made of, for example, a GaN substrate. The n-type buffer layer 102 is made of, for example, GaN having a thickness of 1 μm. The n-type cladding layer 103 is made of, for example, AlGaN having a thickness of 2 μm. The n-side optical confinement layer 104 is made of GaN having a thickness of 0.1 μm, for example. The planar active layer 105 has a multiple quantum well structure including, for example, an InGaN well layer having a thickness of 3 nm and an InGaN barrier layer having a thickness of 4 nm. The cap layer 106 is made of, for example, AlGaN having a thickness of 10 nm. The p-side optical confinement layer 107 is made of, for example, GaN having a thickness of 0.1 μm. The current blocking layer 108 is made of AlN having a thickness of 0.1 μm, for example, and also has a function as a light distribution control layer due to a difference in refractive index in the horizontal direction. The p-type cladding layer 110 has a 130-period superlattice structure made of, for example, GaN with a thickness of 2.5 nm and AlGaN with a thickness of 2.5 nm. The p-type contact layer 111 is made of, for example, GaN having a thickness of 0.1 μm. The n-type impurity is, for example, Si, and the p-type impurity is, for example, Mg.

The dimensions of each waveguide are determined as follows, for example. The dimensions of the active MMI waveguide 109b are determined with reference to the MMI theory described in Non-Patent Document 1, for example. The beat length L _π derived from this MMI theory is given by equation (1).

Here, W is MMI waveguide width, n _r is the equivalent refractive index of the waveguide, n _c is the waveguide outside of the equivalent refractive index, lambda ₀ is the free space wavelength of the guided light. σ is 0 in the TE mode and 1 in the TM mode. When the length L of the MMI waveguide satisfies the formula (2), the MMI waveguide operates as a 1 × N waveguide.

Further, when the expression (3) is satisfied, the MMI waveguide operates as an N × N waveguide.

Referring to this theory, it is possible to design the MMI waveguide so that single transverse mode light is obtained at both ends of the MMI waveguide. For example, in the above embodiment, the dimensions of the active MMI waveguide 109b are as follows: when the width is about 2 to 4 μm, the length is 50 to 150 μm, when the width is about 4 to 5 μm, the length is 150 to 250 μm, and the width Is about 5 to 6 μm, and the length is 250 to 350 μm, single transverse mode light is obtained at both ends of the active MMI waveguide 109b. This is very different from the case where only multimode light is obtained at both ends of a normal multimode waveguide.

The widths of the first and second active

fundamental mode waveguides

109a and 109c are determined so that single transverse mode light obtained at both ends of the active MMI waveguide 109b can be guided stably. Here, for example, it is 1 to 2 μm. Further, the total length of the active waveguide 109 is determined from the viewpoints of desired element characteristics and manufacturing cost. For example, it is 600 to 800 μm.

The lengths of the first active fundamental mode waveguide 109a and the second active fundamental mode waveguide 109c are determined so that the first active fundamental mode waveguide 109a is longer than the second active fundamental mode waveguide 109c. It is done. Here, for example, when the length of the active MMI waveguide 109b is 200 μm and the total length of the active waveguide 109 is 600 μm, the length of the first active fundamental mode waveguide 109a is 250 to 350 μm, and the second active fundamental mode guide is The length of the waveguide 109c is preferably 50 to 150 μm.

Note that the intensity of the emitted light tends to increase as the width of the active MMI waveguide 109b increases and the number of waveguide modes increases. The reason for this is that the emitted light is a part of the guided light that is not self-imaged at the input and output ends of the active MMI waveguide 109b, but is emitted outside the waveguide as non-guided light. This is because as the number of waveguide modes in the waveguide 109b increases, the probability that self-imaging cannot be performed increases. Therefore, it is preferable to increase the length of the first active fundamental mode waveguide 109a as the width of the active MMI waveguide 109b becomes wider in order to enhance the effect of removing the emitted light. In our study, it has been found that, for example, by setting the length to the minimum length L ₀ that satisfies the 1 × 1-MMI condition, a sufficient radiation removal effect for obtaining a good beam shape can be obtained. L ₀ is approximated as Equation (4) from Equation (1) and Equation (2) when the difference in equivalent refractive index inside and outside the waveguide is sufficiently large.

In the present invention, an active MMI semiconductor laser in which a part of the active waveguide 109 is an MMI waveguide 109b has a planar type active layer 105 continuous in the horizontal direction, and the active MMI waveguide 109b to the active waveguide 109 The length to the front end is longer than the length from the active MMI waveguide 109b to the rear end of the active waveguide 109. That is, the length of the first active fundamental mode waveguide 109a located on the output side is longer than the length of the second active fundamental mode waveguide 109c located on the opposite side via the active MMI waveguide 109b. As a result, light emitted without being guided from the active MMI waveguide 109b can be efficiently removed, and a good beam shape can be obtained.

Next, a manufacturing method of the semiconductor laser according to the first embodiment will be described with reference to FIG. A 300 hPa vacuum MOVPE apparatus is used for manufacturing the element structure. A carrier gas is a mixed gas of hydrogen and nitrogen, and trimethylgallium, trimethylaluminum, and trimethylindium are used as Ga, Al, and In sources, respectively. Silane is used as the n-type impurity, and biscyclopentadienyl magnesium is used as the p-type impurity.

After introducing the n-type GaN substrate 101 into the growth apparatus, the substrate is heated while supplying ammonia, and the growth is started when the growth temperature is reached. In the first growth, an n-type GaN buffer layer 102, an n-type AlGaN cladding layer 103, an n-side GaN optical confinement layer 104, an active layer 105 having a multiple quantum well structure comprising an InGaN well layer and an InGaN barrier layer, an AlGaN cap layer 106, a p-side GaN optical confinement layer 107, and an AlN current blocking layer 108 are formed. The growth temperature is, for example, 200 to 800 ° C. for the AlN current blocking layer 108, 800 ° C. for the active layer 105, and 1100 ° C. otherwise. Since the AlN current blocking layer 108 is grown at a low temperature, it is amorphous at the end of the first growth.

A SiO ₂ film is deposited thereon, and a SiO ₂ mask having stripe-shaped openings is formed using a normal photolithography technique. Next, a mixed solution of phosphoric acid and sulfuric acid is maintained at 50 to 200 ° C. to form an etching solution, and a stripe-shaped active waveguide 109 is formed in the AlN current blocking layer 108. At this time, amorphous AlN is easily etched, and single crystal GaN is difficult to etch. Therefore, etching with high selectivity and good controllability is performed. Further, for each of the

waveguides

109a, 109b, and 109c constituting the active waveguide 109, a desired shape can be easily and accurately formed by appropriately setting the shape of the photolithography mask.

Next, the substrate is again put into the growth apparatus, the substrate is heated while supplying ammonia, and the second growth is started when the growth temperature is reached. At this time, the AlN current blocking layer 108 is single-crystallized in the process of raising the temperature of the substrate. Next, a p-type AlGaN / GaN superlattice cladding layer 110 and a p-type GaN contact layer 111 are formed. Thereafter, the p-side electrode 112 is formed on the upper surface, and the n-side electrode 113 is formed on the lower surface.

The above manufacturing method does not require etching removal of the active layer 105 within a range in which current and light are substantially distributed, and can be applied to a material system such as a GaN system or an AlGaInP system. Further, by appropriately controlling the material and thickness of the current blocking layer 108, the second temperature rise condition, etc., the region located under the waveguide 109 in the active layer 105 continuous in the horizontal direction is good. The crystallinity can be lowered only in the region located under the current blocking layer 108 while maintaining the crystallinity. Thereby, the light absorption in a light absorption area | region can be enlarged, and it becomes possible to improve the removal effect of radiated light more.

Note that the composition of the current blocking layer 108 is preferably Al _x In _y Ga _1-xy N (0.4 ≦ x ≦ 1, 0 ≦ y ≦ 0.6, 0 ≦ x + y ≦ 1). Thereby, the effect of controlling the current distribution and the light distribution can be sufficiently obtained. More specifically, when the band gap of the current blocking layer is reduced, the energy barrier against carriers is reduced, current components that do not contribute to laser oscillation increase exponentially, and the operating current increases rapidly. Further, when the refractive index of the current blocking layer is increased, the light confinement effect in the horizontal direction is weakened, and the horizontal transverse mode stability of light is rapidly deteriorated. In order to suppress these influences and control the current distribution and the light distribution well, the composition of the current blocking layer 108 is Al _x In _y Ga _1-xy N (0.4 ≦ x ≦ 1, 0 ≦ y ≦ 0.6, 0 ≦ x + y ≦ 1) is preferable.

The above embodiment and the above manufacturing method are exemplifications, and various modifications are possible, and those skilled in the art can understand that such modifications are also within the scope of the present invention. For example, the planar active layer 105 does not need to be continuous over the entire element, and the active layer may be interrupted in a region where current and light are not substantially distributed. The planar active layer 105 may not be flat as long as it is continuous in a region where current and light are substantially distributed, and may have a step or an unevenness.

In addition, coupling between the first active fundamental mode waveguide 109a and the active MMI waveguide 109b, or between the second active fundamental mode waveguide 109c and the active MMI waveguide 109b. An active tapered waveguide for reducing loss may be included. Here, the length of the first active fundamental mode waveguide 109a is equal to the length of the active taper waveguide provided between the first active fundamental mode waveguide 109a and the active MMI waveguide 109b. The effect of removing the emitted light can be improved.

Further, referring to the MMI theory described in Non-Patent Document 1, it is possible to design the active MMI waveguide 109b so that self-imaging of odd mode light is not allowed. In this case, even if the first active fundamental mode waveguide 109a and the second active fundamental mode waveguide 109c are designed so that not only fundamental mode light but also primary mode light can be guided, the single active fundamental mode waveguide 109a and the second active fundamental mode waveguide 109c One transverse mode operation can be realized.

Further, the length of the active waveguide 109 may be shorter than the total element length of the semiconductor light emitting element. For example, a current non-injection region may be provided at one end or both ends of the active waveguide 109, and another passive waveguide may be connected. Furthermore, the present invention can be applied to a semiconductor light emitting device other than a semiconductor laser, for example, a semiconductor optical amplifier.

This application claims priority based on Japanese Patent Application No. 2008-085603 filed on Mar. 28, 2008, the entire disclosure of which is incorporated herein.

The present invention can be widely applied to semiconductor light emitting devices and manufacturing methods thereof.

Claims

A planar active layer;
A current blocking layer for constricting a current flowing into the active layer;
An inner stripe-type active waveguide constituted by a stripe-shaped opening of the current blocking layer,
The active waveguide is
An active multimode interference waveguide;
A first single mode waveguide extending from the active multimode interference waveguide to the exit end;
A second single mode waveguide extending from the active multimode interference waveguide opposite to the first single mode waveguide;
A semiconductor light emitting device in which a length of the first single mode waveguide is longer than a length of the second single mode waveguide.
The free space wavelength of light guided through the first single-mode waveguide is λ (μm), the width of the active multimode interference waveguide is W (μm), and the equivalent refractive index of the active multimode interference waveguide Where n is
The length of the first single mode waveguide, n × W 2 / λ semiconductor light-emitting device according to claim 1, characterized in that it ([mu] m) or more.
3. The semiconductor light emitting element according to claim 1, wherein a length of the first single mode waveguide is equal to or longer than a length of the active multimode interference waveguide.
The active layer is made of a group III nitride semiconductor,
The current blocking layer is made of Al x In y Ga 1-xy N (0.4 ≦ x ≦ 1, 0 ≦ y ≦ 0.6, 0 ≦ x + y ≦ 1). 4. The semiconductor light emitting device according to claim 3.
An active tapered waveguide is provided between the active multimode interference waveguide and the first single-mode waveguide and / or the second single-mode waveguide. The semiconductor light emitting device according to one item.
The crystallinity of a region of the active layer located under the current blocking layer is lower than the crystallinity of a region of the active layer located under the active waveguide. The semiconductor light emitting device according to any one of 5.
Forming a planar active layer,
Forming a current blocking layer for constricting the current flowing into the active layer;
Forming an inner stripe type active waveguide constituted by a stripe-shaped opening of the current blocking layer;
In the formation of the active waveguide,
An active multimode interference waveguide, a first single mode waveguide extending from the active multimode interference waveguide to the output end;
And forming a second single mode waveguide extending from the active multimode interference waveguide opposite to the first single mode waveguide;
The length of the first single mode waveguide is longer than the length of the second single mode waveguide.