JP2005302910A - Semiconductor light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to allow an n-type quaternary guide layer which is provided directly under the n side of the activity layer of a mesa portion, to be thinner, and to make it possible to improve breakdown voltage by making it possible to allow pn block thickness to be sufficiently thick, in other words, to make it possible to set independently the degree of the local existence of light in the n side and composition wavelength (= a refractive index), relating to a semiconductor light emitting device. <P>SOLUTION: A semiconductor light emitting device comprises an n-type InP substrate 1, a mesa structure comprising an n-type quaternary light guide layer 2 extending in an axis direction on the substrate 1, an activity layer 3 extending on the light guide layer 2, a p-type cladding layer 6 formed on the activity layer 3, a p-side electrode 9 connected with the p-side cladding layer 6 and an n-side electrode 10 connected with the substrate 1, and a p-type quaternary embedding layer 12 allowing both sides of the mesa structure to be embedded in the layer. The refractive index of the light guide layer 2 is large in comparison with that of the substrate 1. The refractive index of the p-type quaternary embedding layer 12 for allowing the mesa side surface of the light guide layer 2 to be embedded in the layer is large in comparison with that of the substrate 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to improvements in semiconductor light emitting devices such as high power semiconductor lasers.

  In recent years, for example, with the explosive increase in Internet-related demand, in optical communication / optical transmission, efforts to increase the speed and capacity have become active. Large capacity is being realized by rapid development.

  This technology is supported by a single-wavelength laser and a wavelength-tunable laser that stably supply a large number of light beams of different wavelengths, and a light that amplifies and relays a large number of optical signals transmitted through an optical fiber in a lump. It is a high-power semiconductor laser that is a fiber amplifier and is used as a pumping light source for this optical fiber amplifier.

  By the way, to increase the output of a semiconductor laser, it is necessary to increase the internal quantum efficiency and reduce the internal loss. Also, by increasing the active layer width in the buried waveguide structure, the light output at the time of high injection is increased. It is known that the saturation of can be suppressed.

  It is known that most of the internal loss in a semiconductor laser is caused by IVBA (Inter-Valence-Band Absorption) in a p-type doped semiconductor. It is known that this internal loss increases in a state substantially proportional to the doping concentration.

  Therefore, it is possible to reduce the internal loss of the semiconductor laser by reducing the doping concentration in the upper cladding layer whose conductivity type is p-type, and in fact, the doping concentration in a part of the p-side cladding layer. By reducing the internal loss, the internal loss decreased.

  However, it is known that p-type semiconductors have higher resistance than n-type semiconductors, and reducing the doping concentration increases the series resistance of the element. As a result, when the doping concentration is reduced, a decrease in light emission intensity is induced by an increase in the amount of heat generated with an increase in series resistance, and an increase in light output that would be realized by reducing internal loss is counteracted. Therefore, the expected high light output cannot be obtained.

  The present inventors have made a prototype of a semiconductor laser represented as a cut-away front view of the main part of FIG. 8 in order to reduce the loss due to doping in the p-side semiconductor by unevenly distributing the light distribution to the n-side. did.

In FIG. 8, 1 is an n-type InP substrate, 2 is an n-type quaternary GaInAsP light guide layer, 3 is an active layer, 4 is a p-type InP buried layer, 5 is an n-type InP current blocking layer, and 6 is a p-type. InP cladding layer, 7 is a p-type GaInAsP contact layer, 8 is a SiO ₂ passivation layer, 9 is a p-side electrode, 10 is an n-side electrode, and 11 is a pn block layer thickness.

  As can be seen from this figure, in this semiconductor laser, an n-type quaternary GaInAsP light guide layer 2, for example, an n-type GaInAsP light guide layer 2 having a thickness of 0.75 μm and a composition wavelength of 0.95 μm is provided on the n side of the active layer 3. The internal loss was reduced by the provision of this, and it succeeded in increasing the conversion efficiency of the drive current versus the optical output immediately after the threshold of laser oscillation.

  However, as the equivalent refractive index in the waveguide core including the active layer and the guide layer becomes high, the cut-off width of the transverse mode is narrowed from 3.2 μm to 2.4 μm, resulting in the active layer width. The light output saturation level has been lowered.

  Yamada et al. Of Anritsu Co., Ltd. deposited a thick quaternary mixed crystal semiconductor layer on the lower side of the active layer, that is, on the n side, and localized the light distribution on the n side. The internal loss has been reduced by reducing the distribution of light existing in the side semiconductor (see, for example, Non-Patent Document 1 and Non-Patent Document 2).

  However, in the prior arts shown in Non-Patent Documents 1 and 2, the 0.95 μm semiconductor mixed crystal, which is a quaternary cladding layer, has a small Ga composition of 2.8% and an As composition of 5.8%. As shown, when the film is deposited to a thickness of 7.5 μm, segregation, distortion, and defects are likely to occur. In addition, since the quaternary mixed crystal semiconductor has a higher thermal resistance than the InP substrate which is a binary semiconductor, the presence of a thick quaternary semiconductor layer hinders heat dissipation and is detrimental to high output operation. Furthermore, when the n-side mesa height is lowered in order to increase the uneven distribution effect of light on the n-side, the thickness of the current blocking layer becomes very thin and high current operation, that is, high voltage application. At times, there is a problem with the withstand voltage of the current blocking layer.

  FIG. 9 is a front view of a principal part showing a semiconductor laser having a lower n-side mesa height, and the same symbols as those used in FIG. 8 represent the same parts or have the same meaning.

As can be seen from the figure, the n-type quaternary light guide layer 2 is formed thick, the mesa height on the n side is low, and the pn block layer thickness 11 is comparable to that of the semiconductor laser shown in FIG. Then it becomes thinner.
Yasuaki Nagashima et al. , “Novel Asymmetric-Cladding 1.48-μm Pump Laser With Extremely High Slope Efficiency and CW Output Power of> 1W”, IEEE / LEOS Annual Meet. PDI. 4 Atsushi Yamada et al., “2003 IEICE General Conference”, C-4-13

  In the present invention, the n-type quaternary guide layer is provided immediately below the mesa portion on the active layer n side. However, the n-type quaternary guide layer can be made thin, and the pn block layer thickness is sufficiently increased. This makes it possible to improve the breakdown voltage. In other words, the degree of localization of light on the n side, the composition wavelength (= refractive index), and the pn block layer thickness can be set independently.

  Further, the thickness of the p layer and the n layer and the composition wavelength (= refractive index) can be set independently to increase the degree of freedom in designing the semiconductor laser structure.

  Furthermore, it is possible to sufficiently increase the layer thickness in the semi-insulating semiconductor buried type current blocking layer so that a high breakdown voltage can be maintained, and the thickness and composition wavelength in the current blocking layer and the n layer can be set. An attempt is made to improve the degree of freedom in designing the laser structure by enabling independent setting.

  In a semiconductor light emitting device according to the present invention, an n-type compound semiconductor substrate (for example, n-type InP substrate 1) and an n-side light guide that extends in the axial direction on the substrate and has an n-type conductivity type A mesa structure including a layer (eg, n-type quaternary GaInAsP light guide layer 2), an active layer (eg, active layer 3) extending on the n-side light guide layer in the mesa structure, and the active layer A p-side cladding layer (for example, p-type cladding layer 6) formed on the p-type, and a p-side electrode (for example, p-side electrode 9) electrically connected to the p-side cladding layer; An n-side electrode (for example, n-side electrode 10) electrically connected to the substrate and a current blocking layer (for example, p-type quaternary GaInAsP) including at least one semiconductor layer embedded on both sides of the mesa structure And the refractive index of the n-side light guide layer is The refractive index of the current blocking layer embedded in the mesa side surface of the n-side light guide layer is larger than the refractive index of the substrate and larger than the refractive index of the substrate. It is basic.

  By adopting the above means, it is sufficient to make the n-side guide layer in the mesa portion thin, for example, about 0.7 μm, and therefore, the generation of crystal defects is suppressed. Further, since the pn block layer can be made sufficiently thick, a sufficient breakdown voltage can be secured, in other words, the degree of localization of light on the n side and the pn block layer thickness can be set independently. There are advantages. Furthermore, since the thickness and composition wavelength (refractive index) of the p layer and n layer can be set independently, the degree of freedom in designing the laser structure has been improved. The current block layer thickness can be sufficiently increased not only in a semiconductor laser using a pn block layer for embedding a mesa portion but also in a semiconductor laser using a semi-insulating semiconductor embedded type current block layer. Therefore, the withstand voltage can be maintained high, and the thickness and composition wavelength in the current blocking layer and the n layer can be set independently, so that the degree of freedom in designing the laser structure can be improved. As a result, a wider active layer width and a smaller internal loss can be realized at the same time. As a result, it is possible to operate with a higher light output.

  FIG. 1 is a front view of a principal part showing a semiconductor laser which is an embodiment for carrying out the present invention. The same symbols as those used in FIGS. 8 and 9 represent the same parts or have the same meanings. Shall have.

In the figure, 1 is an n-type InP substrate, 2 is an n-type quaternary GaInAsP light guide layer, 3 is an active layer, 4 is a p-type InP buried layer, 5 is an n-type InP current blocking layer, and 6 is a p-type InP. The cladding layer, 7 is a p-type GaInAsP contact layer, 8 is a SiO ₂ passivation layer, 9 is a p-side electrode, 10 is an n-side electrode, 11 is a pn block layer thickness, and 12 is a p-type quaternary GaInAsP buried layer. Yes.

  In the illustrated semiconductor laser, an n-type quaternary light guide layer 2 having an energy band gap slightly narrower than that of the substrate 1 and thus having a slightly higher refractive index is disposed on the n side of the active layer 3 in the mesa portion. The light distribution is unevenly distributed on the n side. In order to reduce the refractive index difference between the mesa portion and the side of the mesa and increase the cut-off width of the lateral higher-order mode, the side surface of the mesa portion is lower than the position of the active layer 3 and active. A semiconductor layer having a slightly narrower energy band gap than the p-type InP buried layer 4 and thus having a high refractive index, that is, a p-type quaternary buried layer 12 is disposed as close as possible to the layer 3. . The reason why the p-type quaternary buried layer 12 is doped p-type is to secure the pn block thickness 11 by at least the same thickness as that of the conventional buried structure.

  Even in the case of a semiconductor laser using a semi-insulating semiconductor buried type current blocking layer instead of the p-type InP buried layer 4 instead of the pn block structure described above, the side surface of the mesa portion is the same as described above. The energy band gap is slightly narrower than the position of the active layer 3 and as close as possible to the active layer 3 as compared with the semi-insulating semiconductor buried type current blocking layer. Therefore, the refractive index is slightly higher. Insulating semiconductor layers are disposed on both sides.

FIG. 2 is a perspective view showing a principal part of a semiconductor laser for explaining the first embodiment according to the present invention. In FIG. 2, 21 is an n-type InP substrate, 22 is an n-type having a composition wavelength of 950 nm and a thickness of 750 nm. GaInAsP light guide layer, 23 is an MQW (multiple quantum wells) active layer made of GaInAsP having a PL (photoluminescence) wavelength of 1450 nm, 24 is a p-type InP current blocking layer, 25 is a p-type GaInAsP current block having a composition wavelength of 950 nm and a thickness of 750 nm 26 is a p-type InP current blocking layer, 27 is an n-type InP current blocking layer, 28 is a p-type InP cladding layer, 29 is a p-type GaInAsP contact layer having a thickness of 500 nm, and 30 is made of SiO ₂ having a thickness of 300 nm. Passivation layer, 31 is p-side electrode, 32 is n-side Each electrode is shown. Incidentally, W indicates the width of the active layer 23, which is 4.0 μm here, and in this semiconductor laser, the p-type InP current blocking layer 24 may be omitted. Furthermore, a p-type or non-doped quaternary GaInAsP light guide layer thinner than the n-type GaInAsP light guide layer 22 may be inserted between the MQW active layer 23 and the p-type InP cladding layer 28. Furthermore, part or all of the n-type GaInAsP light guide layer 22 on the side in contact with the MQW active layer 23 may be non-doped.

  The semiconductor laser of Example 1 seen in FIG. 2 is a specific description of the semiconductor laser outlined in FIG. 1, and its operation and effects remain unchanged.

FIG. 3 is a perspective view of a principal part showing a semiconductor laser for explaining the second embodiment according to the present invention. In FIG. 3, 33 is an n-type InP substrate, and 34 is a rib waveguide type having a height of 750 nm. An n-type GaInAsP light guide layer having a composition wavelength of 950 nm and a thickness of 1500 nm, 35 an MQW active layer made of GaInAsP having a PL wavelength of 1450 nm, 36 a p-type GaInAsP current blocking layer having a composition wavelength of 950 nm and a thickness of 750 nm, and 37 a p-type InP current blocking layer, 38 is an n-type InP current blocking layer, 39 is a p-type InP cladding layer, 40 is a p-type GaInAsP contact layer having a thickness of 500 nm, 41 is a passivation layer made of SiO ₂ having a thickness of 300 nm, and 42 is ap Side electrodes 43 are n-side electrodes, respectively. In the second embodiment, there is no p-type InP layer between the n-type InP substrate and the p-type GaInAsP current blocking layer 36. However, as in the first embodiment, the p-type InP current blocking layer 24 may be inserted. good. Furthermore, a p-type or non-doped quaternary GaInAsP light guide layer thinner than the n-type GaInAsP light guide layer 34 may be inserted between the MQW active layer 35 and the p-type InP cladding layer 39.

FIG. 4 is a perspective view of a principal part showing a semiconductor laser for explaining a third embodiment according to the present invention. In FIG. 4, 44 is an n-type InP substrate, 45 is an n-type having a composition wavelength of 950 nm and a thickness of 750 nm. GaInAsP light guide layer, 46 is an MQW active layer made of GaInAsP with a PL wavelength of 1450 nm, 47 is a p-type InP cladding layer, 48 is a p-type GaInAsP contact layer, 49 is a Fe-doped semi-insulating InP current blocking layer, and 50 is a composition wavelength Fe-doped semi-insulating GaInAsP current blocking layer having a thickness of 750 nm and a thickness of 750 nm, 51 is a Fe-doped semi-insulating InP current blocking layer, 52 is a passivation layer made of SiO ₂ having a thickness of 300 nm, 53 is a p-side electrode, and 54 is n Each side electrode is shown. The width of the active layer 46 is 4.0 μm, and the Fe-doped semi-insulating InP layer 49 may be omitted in the third embodiment. Further, part or all of the n-type GaInAsP light guide layer 45 on the side in contact with the MQW active layer 46 may be non-doped.

FIG. 5 is a perspective view showing a principal part of a semiconductor laser for explaining a fourth embodiment according to the present invention. In the figure, 55 is an n-type InP substrate, 56 is an n-type having a composition wavelength of 950 nm and a thickness of 750 nm. GaInAsP light guide layer, 57 is an MQW active layer made of GaInAsP with a PL wavelength of 1450 nm, 58 is a Fe-doped semi-insulating GaInAsP current blocking layer having a composition wavelength of 950 nm and a thickness of 750 nm, 59 is a Fe-doped semi-insulating InP current blocking layer, Reference numeral 60 denotes an n-type InP current blocking layer, 61 denotes a p-type InP cladding layer, 62 denotes a p-type GaInAsP contact layer having a thickness of 500 nm, 63 denotes a passivation layer made of SiO ₂ having a thickness of 300 nm, 64 denotes a p-side electrode, 65 denotes N-side electrodes are shown respectively. The width of the active layer 57 is 4.0 μm, and in this Example 4, there is no Fe-doped semi-insulating InP layer between the n-type InP substrate 55 and the semi-insulating GaInAsP current blocking layer 58. However, as in Example 3, an Fe-doped semi-insulating InP current blocking layer may be interposed.

FIG. 6 is a perspective view showing a principal part of a semiconductor laser for explaining a fifth embodiment of the present invention. In the figure, 66 is a p-type InP substrate, and 67 is an MQW active layer made of GaInAsP having a PL wavelength of 1450 nm. 68 is an n-type GaInAsP light guide layer having a composition wavelength of 950 nm and a thickness of 750 nm, 69 is a p-type InP current blocking layer, 70 is an n-type InP current blocking layer, and 71 is a p-type GaInAsP current having a composition wavelength of 950 nm and a thickness of 750 nm. Block layer, 72 is p-type InP current blocking layer, 73 is n-type InP cladding layer, 74 is n-type GaInAsP contact layer having a thickness of 500 nm, 75 is a passivation layer made of SiO ₂ having a thickness of 300 nm, 76 is an n-side electrode , 77 indicate p-side electrodes, respectively. The active layer 67 has a width of 4.0 μm. Further, when fabricating the fifth embodiment, care must be taken so that the n-type InP current blocking layer 70 and the n-type InP cladding layer 73 are not short-circuited in the vicinity of the top surface of the mesa.

FIG. 7 is a perspective view showing a principal part of a semiconductor laser for explaining a sixth embodiment according to the present invention. In FIG. 7, 78 is a p-type InP substrate, 79 is an MQW active layer made of GaInAsP having a PL wavelength of 1450 nm. , 80 is an n-type GaInAsP light guide layer having a composition wavelength of 950 nm and a thickness of 750 nm, 81 is a p-type InP current blocking layer, 82 is an n-type InP current blocking layer, 83 is a p-type GaInAsP current blocking layer having a composition wavelength of 950 nm, 84 Denotes an n-type InP cladding layer, 85 denotes an n-type GaInAsP contact layer having a thickness of 500 nm, 86 denotes a passivation layer made of SiO ₂ having a thickness of 300 nm, 87 denotes an n-side electrode, and 88 denotes a p-side electrode. The active layer 79 has a width of 4.0 μm. Further, when fabricating the sixth embodiment, care must be taken so that the n-type InP current blocking layer 82 and the n-type InP cladding layer 84 are not short-circuited in the vicinity of the top surface of the mesa.

  In each of the embodiments described above, a GaInAsP-based compound semiconductor fabricated on an InP substrate is used as a material constituting the semiconductor laser, but this can be replaced with a GaAlInAs-based compound semiconductor. The same effect can be obtained by combining materials that can be used.

  In the present invention, the present invention can be implemented in many forms including the above-described embodiment, which will be exemplified below as supplementary notes.

(Appendix 1)
an n-type compound semiconductor substrate;
A mesa structure including an n-side light guide layer extending in an axial direction on the substrate and having an n-type conductivity;
An active layer extending on the n-side light guide layer in the mesa structure;
A p-side cladding layer formed on the active layer and having a p-type conductivity;
A p-side electrode electrically connected to the p-side cladding layer and an n-side electrode electrically connected to the substrate;
A current blocking layer composed of at least one semiconductor layer embedded on both sides of the mesa structure;
The refractive index of the n-side light guide layer is larger than the refractive index of the substrate, and the refractive index of at least a part of the current blocking layer embedding the mesa side surface in the n-side light guide layer is A semiconductor light emitting device characterized by being larger than a refractive index.

(Appendix 2)
The current blocking layer has a pnpn thyristor structure configured by combining a p-type semiconductor layer and an n-type semiconductor layer, and a part of the conductivity type in the current blocking layer having a refractive index larger than the refractive index of the substrate. The semiconductor light-emitting device according to appendix 1, wherein p is a p-type.

(Appendix 3) A semiconductor light-emitting device, wherein the current blocking layer is formed of a high-resistance semi-insulating semiconductor layer, and the refractive index of at least a part of the current blocking layer is larger than the refractive index of the substrate. .

(Appendix 4)
4. The semiconductor light-emitting device according to any one of appendices 1 to 3, wherein the n-side light guide layer whose conductivity type is n-type has a thickness of 0.5 μm or more and 2 μm or less.

(Appendix 5)
The interface on the side close to the active layer of the current blocking layer whose refractive index is larger than the refractive index of the substrate is the same as or far from the active layer side interface of the n-side light guide layer The semiconductor light-emitting device according to any one of appendices 1 to 4, wherein the semiconductor light-emitting device is located.

(Appendix 6)
an n-type compound semiconductor substrate;
A rib waveguide structure including an n-side light guide layer extending in an axial direction on the substrate and having an n-type conductivity;
An active layer extending on the n-side light guide layer in the rib waveguide structure;
A p-side cladding layer formed on the active layer as well as on the rib waveguide and having a p-type conductivity;
A p-side electrode electrically connected to the p-side cladding layer and an n-side electrode electrically connected to the substrate;
The refractive index of the n-side light guide layer is larger than the refractive index of the substrate, and at least one of the current blocking layers embedded on both sides of the rib in the rib waveguide structure including the n-side light guide layer. A semiconductor light emitting device characterized in that the refractive index of the portion is larger than the refractive index of the substrate.

(Appendix 7)
The current blocking layer has a pnpn thyristor structure configured by combining a p-type semiconductor layer and an n-type semiconductor layer, and a part of the conductivity type in the current blocking layer having a refractive index larger than that of the substrate. The semiconductor light-emitting device according to appendix 6, wherein p is a p-type.

(Appendix 8)
8. The semiconductor light-emitting device according to appendix 6 or 7, wherein the n-side light guide layer whose conductivity type is n-type has a thickness of 2 μm or less.

(Appendix 9)
The interface on the side close to the active layer of the current blocking layer whose refractive index is larger than the refractive index of the substrate is the same as or far from the active layer side interface of the n-side light guide layer 9. The semiconductor light emitting device according to any one of appendices 6 to 8, wherein the semiconductor light emitting device is located.

(Appendix 10) a p-type compound semiconductor substrate;
A rib waveguide structure formed extending in the axial direction on the substrate, an active layer extending in the axial direction on the rib waveguide structure, and extending in the axial direction on the active layer A mesa structure composed of an n-side light guide layer whose conductivity type is n-type,
An n-side cladding layer formed on the mesa structure and having an n-type conductivity;
An n-side electrode electrically connected to the n-side cladding layer and a p-side electrode electrically connected to the substrate;
Among the current blocking layers embedded in both sides of the mesa structure including the n-side light guide layer and having a refractive index larger than that of the substrate, the conductivity type is p-type. A semiconductor light emitting device characterized in that a refractive index of at least a part or all of the current blocking layer is larger than a refractive index of the substrate.

(Appendix 11)
11. The semiconductor light-emitting device according to appendix 10, wherein the n-type light guide layer having a conductivity type of n-type has a thickness of not less than 0.5 μm and not more than 2 μm.

It is a principal part cutting front view showing the semiconductor laser which is one form for implementing this invention. It is a principal part perspective view showing the semiconductor laser for demonstrating Example 1 by this invention. It is a principal part perspective view showing the semiconductor laser for demonstrating Example 2 by this invention. It is a principal part perspective view showing the semiconductor laser for demonstrating Example 3 by this invention. It is a principal part perspective view showing the semiconductor laser for demonstrating Example 4 by this invention. It is a principal part perspective view showing the semiconductor laser for demonstrating Example 5 by this invention. It is a principal part slope view showing the semiconductor laser for demonstrating Example 6 by this invention. It is a principal part cutting front view showing the semiconductor laser made as a trial. It is a principal part cutting front view showing the semiconductor laser which made mesa height lower on the n side.

Explanation of symbols

1 n-type InP substrate 2 n-type quaternary light guide layer 3 active layer 4 p-type InP buried layer 5 n-type InP current blocking layer 6 p-type InP cladding layer 7 p-type GaInAsP contact layer 8 SiO ₂ passivation layer 9 p-side electrode 10 n-side electrode 11 pn block thickness 12 p-type quaternary buried layer

Claims (5)

an n-type compound semiconductor substrate;
A mesa structure including an n-side light guide layer extending in an axial direction on the substrate and having an n-type conductivity type;
An active layer extending on the n-side light guide layer in the mesa structure;
A p-side cladding layer formed on the active layer and having a p-type conductivity;
A p-side electrode electrically connected to the p-side cladding layer and an n-side electrode electrically connected to the substrate;
A current blocking layer composed of at least one semiconductor layer embedded on both sides of the mesa structure;
The refractive index of the n-side light guide layer is larger than the refractive index of the substrate, and the refractive index of at least a part of the current blocking layer embedding the mesa side surface in the n-side light guide layer is A semiconductor light emitting device having a large refractive index. The current blocking layer has a pnpn thyristor structure configured by combining a p-type semiconductor layer and an n-type semiconductor layer, and a part of the conductivity type in the current blocking layer having a refractive index larger than that of the substrate. 2. The semiconductor light-emitting device according to claim 1, wherein p is a p-type. The interface on the side close to the active layer of the current blocking layer whose refractive index is larger than the refractive index of the substrate is the same as or far from the active layer side interface of the n-side light guide layer 3. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device is located. an n-type compound semiconductor substrate;
A rib waveguide structure including an n-side light guide layer extending in an axial direction on the substrate and having an n-type conductivity;
An active layer extending on the n-side light guide layer in the rib waveguide structure;
A p-side cladding layer formed on the active layer as well as on the rib waveguide and having a p-type conductivity;
A p-side electrode electrically connected to the p-side cladding layer and an n-side electrode electrically connected to the substrate;
The refractive index of the n-side light guide layer is larger than the refractive index of the substrate, and at least one of the current blocking layers embedded on both sides of the rib in the rib waveguide structure including the n-side light guide layer. A semiconductor light emitting device characterized in that the refractive index of the portion is larger than the refractive index of the substrate. a p-type compound semiconductor substrate;
A rib waveguide structure formed extending in the axial direction on the substrate, an active layer extending in the axial direction on the rib waveguide structure, and extending in the axial direction on the active layer A mesa structure composed of an n-side light guide layer whose conductivity type is n-type,
An n-side cladding layer formed on the mesa structure and having an n-type conductivity;
An n-side electrode electrically connected to the n-side cladding layer and a p-side electrode electrically connected to the substrate;
Among the current blocking layers embedded in both sides of the mesa structure including the n-side light guide layer and having a refractive index larger than that of the substrate, the conductivity type is p-type. A semiconductor light emitting device characterized in that a refractive index of at least a part or all of the current blocking layer is larger than a refractive index of the substrate.

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