JP2008085367A - Semiconductor laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise the reliability in a high-output operation by lessening the end surface deterioration in the high-output operation by lessening the vertical beam expansion and by raising the heat transfer to a heat dissipating body side. <P>SOLUTION: A semiconductor laser device comprises a heat sink 24 having a principal surface, an n-AlGaAs clad layer 30 disposed on the principal surface of the heat sink 24, an AlGaAs active layer 34 disposed on the n-AlGaAs clad layer 30, and a p-AlGaAs clad layer 38 disposed on the AlGaAs active layer 34, wherein the effective refractive index and the heat resistance between a principal surface of the heat sink 24 side of the AlGaAs active layer 34 and a principal surface of the heat sink 24 side of the n-AlGaAs clad layer 30 are made to be smaller, respectively, than the effective refractive index and the heat resistance between a principal surface of the opposite side to the heat sink 24 of the AlGaAs active layer 34 and a principal surface of the opposite side of the heat sink 24 of the p-AlGaAs clad layer 38. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor laser device, and more particularly to a semiconductor laser device that includes a heat radiator and performs a high output operation.

  A semiconductor laser device as a light source for optical information processing, a signal source for optical communication, or a pumping light source of a fiber amplifier is required to have a high output operation. Also, semiconductor laser devices have been required to have a high output operation as a light source for exciting solid lasers used for welding and cutting of metals, for example, YAG lasers. In such a high output operation, it is essential to improve the kink level and reduce the aspect ratio.

  As a known example of a conventional semiconductor laser device, in a semiconductor laser having a ridge waveguide, the refractive index distribution in the thickness direction is made asymmetric when viewed from the active layer, thereby causing a higher-order mode that causes kinks. Therefore, high-speed operation is possible, and the refractive index of the lower cladding layer is increased to increase the refractive index of the upper cladding layer. A configuration is shown in which a large amount of light is distributed in the lower cladding layer by shifting, resulting in a reduced aspect ratio (see, for example, paragraph [0017] of Patent Document 1 and FIG. 2).

  Furthermore, as a well-known example of another semiconductor laser device, by providing a high refractive index guide layer in the radiator-side cladding layer, the light distribution is entirely drawn to the radiator-side cladding layer, so that the light density near the active layer is increased. A configuration is disclosed in which the power is reduced, the COD (optical damage) level is increased, and the power is increased (see, for example, paragraph [0014] of Patent Document 2 and FIG. 1).

  Furthermore, as a known example of another semiconductor laser device, at least one of clads provided in contact with an active layer of a quaternary semiconductor laser such as AlGaInP that performs short-wavelength oscillation is a ternary mixed crystal such as AlInP and GaInP. Consists of a quaternary cladding layer with a superlattice structure formed by periodic stacking of thin-film semiconductors. This reduces the size of the mixed crystal, thereby reducing scattering due to disordering in the mixed crystal and increasing the thermal conductivity. (See, for example, Patent Document 3, paragraph numbers [0011] to [0013] and FIG. 1).

Japanese Patent Application Laid-Open No. 11-233883 Japanese Unexamined Patent Publication No. 7-38193 Japanese Patent Laid-Open No. 7-170017

However, in semiconductor laser devices with high output operation, how to effectively conduct heat generated in the laser chip to the radiator becomes an important issue. In addition to the reduction, the thermal conductivity distribution of the material constituting the semiconductor laser for conducting the generated heat to the heat radiator becomes an important issue.
On the other hand, in a compound semiconductor used for a semiconductor laser, the composition is closely related to the refractive index and also closely related to the thermal conductivity.
For example, according to MA Afromowitz, “Thermal conductivity of Ga _1-x Al _x As alloys”, J. Appl. Phys., Vol. 44, N0. 3, March 1973, pp. 1292-1294, in the case of AlGaAs As the Al composition ratio approaches 0.5, the thermal conductivity decreases. For this reason, depending on the refractive index of the cladding layer disposed on the radiator side and the cladding layer disposed on the non-radiator side, there may be a disadvantageous configuration for transferring heat to the radiator. It was.

  The present invention has been made to solve the above-mentioned problems. The first object is to reduce the vertical beam divergence angle to reduce end face deterioration during high output operation and to improve the heat conduction to the radiator side. Accordingly, it is an object of the present invention to provide a highly reliable semiconductor laser device during high output operation.

  A semiconductor laser device according to the present invention includes a heat dissipating member having one main surface, a first main surface disposed on the main surface of the heat dissipating member and facing the main surface of the heat dissipating member, and the first main surface. A first conductive type first semiconductor layer having a second main surface opposite to the surface, and a second main surface of the first semiconductor layer disposed on the second main surface of the first semiconductor layer. An active layer having a first main surface opposite to the main surface of the active layer and a second main surface opposite to the first main surface; and an active layer disposed on the second main surface of the active layer. A first main surface opposite to the second main surface and a second conductive type second semiconductor layer having a second main surface opposite to the first main surface and the first main surface. The semiconductor layer and the second semiconductor layer are made of a material whose thermal conductivity increases as the refractive index decreases, and the refractive index of the first semiconductor layer is the second semiconductor layer. The effective refractive index between the first main surface of the active layer and the first main surface of the first semiconductor layer is set to be smaller than the refractive index of the active layer. The second main surface of the active layer and the second semiconductor layer And the thermal resistance between the first main surface of the active layer and the first main surface of the first semiconductor layer is lower than the effective refractive index between the second main surface and the second main surface of the active layer. This is smaller than the thermal resistance between the main surface and the second main surface of the second semiconductor layer.

In the semiconductor laser device according to the present invention, the effective refractive index of the first semiconductor layer on the radiator side with respect to the active layer is made lower than the effective refractive index of the second semiconductor layer that is not on the radiator side with respect to the active layer. This increases the light intensity distribution to the side of the active layer that is not on the radiator side, reduces the aspect ratio, reduces the vertical beam divergence angle to ensure good high-power operation, and distributes the active layer to the radiator side. By making the thermal resistance of the provided first semiconductor layer smaller than the thermal resistance of the second semiconductor layer disposed on the non-radiator side with respect to the active layer, good heat conduction to the radiator side is possible. And
Furthermore, the first semiconductor layer and the second semiconductor layer are made of a material whose thermal conductivity increases as the refractive index decreases, and the refractive index of the first semiconductor layer is smaller than the refractive index of the second semiconductor layer. Since it is set, it contributes to the achievement of the above effect.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram of a semiconductor laser device according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the refractive index distribution of the semiconductor layer of the semiconductor laser device according to the present invention.
In the first embodiment, a basic configuration including the second and subsequent embodiments will be described.
In FIG. 1, a semiconductor laser device 10 is composed of a heat sink 12 as a radiator and a semiconductor laser element 13 disposed on the heat sink 12. In the semiconductor laser element 13, a semiconductor layer 16 and a semiconductor layer 18 are stacked with an active layer 14 interposed therebetween. A semiconductor layer 16 is disposed on the opposite side of the active layer 14 from the heat sink 12, and a semiconductor layer 18 is disposed on the heat sink 12 side of the active layer 14.
The semiconductor layer 16 is composed of an n-th layer farthest from the first layer adjacent to the active layer 14 to the heat sink 12, and the thickness of the first layer is ta1, the thermal conductivity is λa1, and the refractive index. , N1, the layer thickness of the (n-1) th layer is tan-1, the thermal conductivity is λan-1, the refractive index is nan-1, the layer thickness of the nth layer is tan, The conductivity is λan and the refractive index is nan.
The semiconductor layer 18 is composed of the m-th layer closest to the heat sink 12 from the first layer adjacent to the active layer 14, and the thickness of the first layer is tb1, the thermal conductivity is λb1, and the refractive index The rate is nb1,..., The layer thickness of the (m-1) th layer is tbm-1, the thermal conductivity is λbm-1, the refractive index is nbm-1, the layer thickness of the mth layer is tbm, The thermal conductivity is λbm and the refractive index is nbm.
In each layer, the main surface on the radiator side is the first main surface, and the main surface opposite to the first main surface, that is, the main surface that is not on the radiator side is the second main surface.

The nth layer of the semiconductor layer 16 is, for example, a p-cladding layer as a second semiconductor, and the mth layer of the semiconductor layer 18 is, for example, an n-cladding layer as a first semiconductor layer. is there.
The configuration of the semiconductor layer 16 and the semiconductor layer 18 in the first embodiment is configured so that the following two conditions (1) and (2) are satisfied. That is, (1) the heat conduction of the semiconductor layer 18 is better than the heat conduction of the semiconductor layer 16.
(2) The effective refractive index of the semiconductor layer 18 is lower than the effective refractive index of the semiconductor layer 16.
That is, the condition (1) is expressed by the equation (1) when the thermal resistance is proportional to the thickness of each layer and inversely proportional to the thermal conductivity. That is,
ta1 / λa1 + ta2 / λa2 + ... + tan-1 / λan-1 + tan / λan> tb1 / λb1 + tb2 / λb2 + ... + tbm-1 / λbm-1 + tbm / λbm (1)
Condition (2) is defined as follows.
Now, the lowest refractive index in each layer is defined as nmin, and the refractive index distribution n (x) of each layer is defined by the refractive index distribution shown in FIG.
Here, t is ½ of the thickness of each layer. For example, in the first layer of the semiconductor layer 18, t = tb1 / 2 and n (x) = nb1.

It is assumed that the effective refractive index can be approximated by the normalized frequency V. The normalized frequency V can be approximated as in equation (2). That is,
V = (2π / λ) [n (x) ² −nmin ² ] ^1/2 t
≒ (2π / λ) [2 nmin x Δn] ^1/2 t (2)
Here, Δn = n (x) −nmin, and λ is an oscillation wavelength.
Thus, the effective refractive index of each layer is characterized by [Δn] ^1/2 t. As a result, condition (2) is expressed by equation (3).
^{[Δna1] 1/2 ta1 + [Δna2} ] 1/2 ta2 + ··· + [Δnan-1] 1/2 tan-1 + [Δnan] 1/2 tan> [Δnb1] 1/2 tb1 + [Δnb2] 1/2 tb2 + ... + [Δnbm-1] ^1/2 tbm-1 + [Δnbm] ^1/2 tbm (3)
As described above, in the semiconductor laser device according to the first embodiment of the present invention, the effective refractive index of the semiconductor layer disposed on the radiator side with respect to the active layer, that is, the first main surface of the active layer and the semiconductor layer 18, the effective refractive index between the first main surface of the m-th layer and the active layer is the effective refractive index of the semiconductor layer disposed on the side opposite to the radiator, that is, the second of the active layer. Since the effective refractive index is lower than the effective refractive index between the main surface of the semiconductor layer 16 and the second main surface of the nth layer of the semiconductor layer 16, the light intensity distribution of the semiconductor laser is opposite to that of the heat sink with respect to the active layer Expands to the semiconductor layer disposed on the side. That is, the light density is reduced by expanding the beam, end face deterioration at high output is less likely to occur, high output operation is possible, and the vertical beam divergence angle is reduced, thereby reducing the aspect ratio.
Furthermore, the thermal resistance of the semiconductor layer disposed on the radiator side with respect to the active layer, that is, the heat between the first main surface of the active layer and the first main surface of the mth layer of the semiconductor layer 18. The resistance of the semiconductor layer disposed on the opposite side of the active layer with respect to the active layer, ie, the second main surface of the active layer and the second main surface of the nth layer among the semiconductor layers 16 And the heat generated by the semiconductor laser generated in the vicinity of the active layer is easily conducted to the radiator.
Therefore, it is possible to configure a semiconductor laser device capable of high output operation and easily conducting heat generated by the high output operation to the heat radiating body. As a result, a highly reliable semiconductor laser with high output operation can be provided.
The second and subsequent embodiments are more specifically configured based on the basic concept of the first embodiment.

Embodiment 2. FIG.
FIG. 3 is a perspective view of a semiconductor laser device according to an embodiment of the present invention. 4 is a cross-sectional view of the semiconductor laser device taken along the line IV-IV in FIG.
The second to fifth embodiments will be described by taking as an example a semiconductor laser device used as a light source for excitation of a solid-state laser having an oscillation wavelength near 810 nm, for example, a YAG laser used for welding or cutting of metal. .
In FIG. 3, a semiconductor laser device 20 is formed of a semiconductor laser element 22 and a CuW heat sink 24 as a radiator. The hatched portion is a proton injection region 26 for current confinement, and the hatching in FIG. 3 does not indicate a cross section. The portion sandwiched between the proton injection regions 26 is a stripe that is a region through which a current flows, and the stripe width is indicated by S. In the semiconductor laser element 22, the laser resonator length is indicated by L and the laser element width is indicated by W.
For example, in the second embodiment, the laser resonator length L = 1000 μm, the laser element width W = 200 μm, and the stripe width S = 60 μm. The thickness of the heat sink 24 is 0.3 mm.

In FIG. 4, the semiconductor laser element 22 includes an n-GaAs substrate 28 and an n-AlGaAs clad layer 30 (first semiconductor layer) on the surface of the n-GaAs substrate 28 sequentially from the n-GaAs substrate 28 side. Al composition ratio x = 0.90, layer thickness t = 1.5 μm), undoped AlGaAs guide layer 32 as the third semiconductor layer (Al composition ratio x = 0.40, layer thickness t = 94 nm), AlGaAs active layer 34 (Al composition ratio x = 0.10, layer thickness t = 16 nm), undoped AlGaAs guide layer 36 (Al composition ratio x = 0.40, layer thickness t = 94 nm) as the fourth semiconductor layer, A p-AlGaAs cladding layer 38 (Al composition ratio x = 0.55, layer thickness t = 1.5 μm) and a p-GaAs contact layer 40 are disposed as semiconductor layers.
The proton injection regions 26 for current confinement are disposed on both sides of the stripe, which is a region where current flows in the center of the element width. In the depth direction of the proton injection region 26, the p-GaAs contact layer 40 is disposed. Protons are implanted from the surface to the middle of the thickness of the p-AlGaAs cladding layer 38.
Further, a p-electrode 42 is disposed on the surface of the p-GaAs contact layer 40.
An n-electrode 44 is formed on the back side of the n-GaAs substrate 28. A gold-plated layer 46 having a thickness of about 3 μm is disposed on the surface of the n-electrode 44. The gold-plated layer 46 and the heat sink 24 are soldered together. Is adhered by.
The second embodiment is a junction-up (J-UP) assembly in which the n-GaAs substrate 28 is disposed on the heat sink 24 side with respect to the AlGaAs active layer 34.

Next, the operation of the semiconductor laser according to the second embodiment will be described.
HC Causey Jr., DD Sell, and MB Panish, “Refractive index of Al _x Ga _1-x As between 1.2 and 1.8 eV”, Appl. Phys. Lett., Vol. 24, No. 2, 15 January 1974, pp 63-65, the refractive index of the AlGaAs-based material monotonously decreases as the Al composition ratio increases, and the refractive index n (x) can be expressed by Equation (4) with respect to the Al composition ratio x. .
n (x) = 3.590−0.710x + 0.091x ² (4)
Since the Al composition ratio of the n-AlGaAs cladding layer 30 in the semiconductor laser device 20 is x = 0.90 and the Al composition ratio of the p-AlGaAs cladding layer 38 is x = 0.55, the refractive index is obtained from the equation (4). When the refractive index is calculated, the refractive index of the n-AlGaAs cladding layer 30 is 3.025, and the refractive index of the p-AlGaAs cladding layer 38 is 3.227.
Accordingly, considering that the undoped AlGaAs guide layer 32 and the undoped AlGaAs guide layer 36 are symmetrical in structure with respect to the refractive index and the layer thickness, the undoped AlGaAs active layer 34 is located on the opposite side of the heat sink 24 with respect to the AlGaAs active layer 34. Since the effective refractive indexes of the AlGaAs guide layer 36 and the p-AlGaAs cladding layer 38 are higher than the effective refractive indexes of the undoped AlGaAs guide layer 32 and the n-AlGaAs cladding layer 30 on the heat sink 24 side with respect to the AlGaAs active layer 34, light The intensity distribution is expanded to the p-AlGaAs cladding layer 38 side opposite to the heat sink 24.
For this reason, the vertical beam divergence angle θv is reduced, and the horizontal beam divergence angle θh is not particularly changed. Therefore, the aspect ratio, which is the ratio of the vertical beam divergence angle θv to the horizontal beam divergence angle θh, is reduced.

Also, there is an inverse relationship between the beam diameter ω and the beam divergence angle of the near field image (NFP). Therefore, when the vertical beam divergence angle θv decreases, the beam diameter of the near field image increases and the light density increases. Therefore, the end face deterioration at the time of high output is reduced, and the reliability of a laser diode (hereinafter referred to as LD) in high output operation can be increased.
Furthermore, when the light intensity distribution expands to the p-AlGaAs cladding layer 38 side opposite to the heat sink 24, free carrier absorption caused by the n-AlGaAs cladding layer 30 is reduced, and light absorption is reduced. As a result, the slope efficiency is improved and a high output operation can be performed.
On the other hand, according to the Afromowitz paper described above, the thermal resistivity increases monotonously up to near 0.5 as the Al composition ratio increases from 0, and the heat increases as the Al composition ratio further increases from near 0.5. It has been shown that resistivity decreases monotonically.
In the semiconductor laser device 20, the Al composition ratio of the n-AlGaAs cladding layer 30 on the heat sink 24 side with respect to the AlGaAs active layer 34 is x = 0.90, and the side opposite to the heat sink 24 with respect to the AlGaAs active layer 34. Since the Al composition ratio of the p-AlGaAs cladding layer 38 is x = 0.55, the thermal conductivity of the n-AlGaAs cladding layer 30 is higher than the thermal conductivity of the p-AlGaAs cladding layer 38. I understand.

According to WB Joice and RW Dixon, “Thermal resistance of heterostructure lasers”, J. Appl. Phys., Vol. 46, No. 2, February 1975, pp.855-862, calculate the thermal resistance of a semiconductor laser. Can do.
Based on this, the thermal resistance of the semiconductor laser device 20 was calculated to be 21.54 ° C./W.
For comparison, the Al composition ratio of the n-AlGaAs cladding layer on the heat sink 24 side is set to x = 0.55 which is the same as the Al composition ratio of the p-AlGaAs cladding layer 38, and the layer thickness is of course the n-AlGaAs cladding layer 30. When the thermal resistance is calculated with the same layer thickness t = 1.5 μm and other specifications as those of the semiconductor laser device 20, the thermal resistance of Comparative Example 1 of this symmetrical refractive index structure is 21.90 ° C./W. became.
Therefore, the semiconductor laser device 20 according to this embodiment has a heat of about 1.6% as compared with the case of Comparative Example 1 in which the Al composition ratio of the p-AlGaAs cladding layer and the n-AlGaAs cladding layer is the same. The resistance can be reduced.

Modification 1
FIG. 5 is a sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention. 5 is also basically the same as the configuration of FIG. 2, and therefore the cross-sectional position of FIG. 5 is also the IV-IV cross section of FIG. In the drawings, the same reference numerals indicate the same or equivalent.
The semiconductor laser device 50 shown in FIG. 5 is different from the semiconductor laser device 20 in that the n-AlGaAs cladding layer 30a has an Al composition ratio x = 0.90, a layer thickness t = 0.4 μm, and p The AlGaAs cladding layer 38a has an Al composition ratio of x = 0.55 and a layer thickness of t = 2.0 μm. Other configurations of the semiconductor laser device 50 are the same as those in the semiconductor laser device 20.
In both the semiconductor laser device 20 and the semiconductor laser device 50, the refractive indexes of the p-AlGaAs cladding layer 38 and the p-AlGaAs cladding layer 38a on the opposite side of the heat sink 24 with respect to the AlGaAs active layer 34 are different from those of the AlGaAs active layer 34. Since the refractive index of the n-AlGaAs cladding layer 30 and the n-AlGaAs cladding layer 30a on the heat sink 24 side is higher than the refractive index, the light intensity distribution is the p-AlGaAs cladding layer 38 and the p-AlGaAs cladding layer on the opposite side of the heat sink 24. It expands to the 38a side.
For this reason, even if the thickness of the n-AlGaAs cladding layer on the heat sink 24 side is slightly thinner than the AlGaAs active layer 34, the n-GaAs substrate 28 is not affected optically. Therefore, in the semiconductor laser device 50, the n-AlGaAs cladding layer 30a has an Al composition ratio of x = 0.90 and a layer thickness of t = 0.4 μm.
In addition, the p-AlGaAs cladding layer 38a, which has a wider light intensity distribution, has an Al composition ratio of x = 0.55, and the layer thickness is t in order to reduce the optical influence of the p-GaAs contact layer 40. = 2.0 μm thick.

In the semiconductor laser device 50, similarly to the semiconductor laser device 20, the thermal conductivity of the n-AlGaAs cladding layer 30a is higher than the thermal conductivity of the p-AlGaAs cladding layer 38a. In the semiconductor laser device 50, the n-AlGaAs cladding layer 30a is thinner than the n-AlGaAs cladding layer 30 in the semiconductor laser device 20, and the distance from the AlGaAs active layer 34 to the heat sink 24 is short. The heat conduction to the heat sink becomes easy and the heat dissipation effect can be enhanced.
The thermal resistance of the semiconductor laser device 50 is about 21.11 ° C./W, which is about 3.6% lower than the thermal resistance of Comparative Example 1, and about 2.0% lower than the thermal resistance of the semiconductor laser device 20. To do.
As described above, in the semiconductor laser device according to the present embodiment, the heat conduction of the n-AlGaAs cladding layer disposed on the heat sink side with respect to the AlGaAs active layer is opposite to the heat sink with respect to the AlGaAs active layer. By improving the thermal conductivity of the p-AlGaAs cladding layer disposed on the n-AlGaAs, the heat generated by the semiconductor laser can be easily conducted to the radiator, and the n-AlGaAs disposed on the radiator side with respect to the AlGaAs active layer. Since the refractive index of the cladding layer is configured to be lower than the refractive index of the p-AlGaAs cladding layer disposed on the opposite side of the heat sink with respect to the AlGaAs active layer, the light intensity distribution of the semiconductor laser is on the opposite side of the heat sink. Expands to the p-AlGaAs cladding layer side, reduces the aspect ratio, and increases the beam diameter to reduce the light density and increase Facet degradation hardly occurs at the time of the force, it is possible to high-output operation.
Furthermore, the absorption of free carriers due to the n-AlGaAs cladding layer is reduced, and the light absorption is reduced, so that the slope efficiency is improved and a high output operation can be performed.
In addition, since the light intensity distribution is expanded to the p-AlGaAs cladding layer side opposite to the radiator, the thickness of the n-AlGaAs cladding layer on the heat sink side can be reduced, Heat conduction can be made easier and the heat dissipation effect can be enhanced.
Therefore, it is possible to configure a semiconductor laser device capable of high output operation and easily conducting heat generated by the high output operation to the heat radiating body. As a result, a highly reliable semiconductor laser with high output operation can be provided.

Embodiment 3 FIG.
FIG. 6 is a perspective view of a semiconductor laser device according to an embodiment of the present invention. FIG. 7 is a cross-sectional view of the semiconductor laser device taken along the line VII-VII in FIG.
In FIG. 6, the semiconductor laser device 54 is formed of a semiconductor laser element 56 and a heat sink 24.
For example, also in the third embodiment, the laser resonator length L = 1000 μm, the laser element width W = 200 μm, and the stripe width S = 60 μm. The thickness of the heat sink 24 is 0.3 mm.
In FIG. 7, a semiconductor laser element 56 includes an n-GaAs substrate 28 and an n-AlGaAs cladding layer 58 (second semiconductor layer) on the surface of the n-GaAs substrate 28 sequentially from the n-GaAs substrate 28 side. Al composition ratio x = 0.55, layer thickness t = 1.5 μm), undoped AlGaAs guide layer 32 (Al composition ratio x = 0.40, layer thickness t = 94 nm) as the fourth semiconductor layer, AlGaAs active layer 34 (Al composition ratio x = 0.10, layer thickness t = 16 nm), undoped AlGaAs guide layer 36 (Al composition ratio x = 0.40, layer thickness t = 94 nm) as the third semiconductor layer, A p-AlGaAs cladding layer 60 (Al composition ratio x = 0.9, layer thickness t = 1.5 μm) and a p-GaAs contact layer 40 are disposed as semiconductor layers. The proton injection regions 26 for current confinement are disposed on both sides of the stripe, which is a region where current flows in the center of the element width. In the depth direction of the proton injection region 26, the p-GaAs contact layer 40 is disposed. The protons are implanted from the surface of the p-AlGaAs to the middle of the thickness of the p-AlGaAs cladding layer 60.

Further, a p-electrode 42 is disposed on the surface of the p-GaAs contact layer 40, and a gold-plated layer 46 having a thickness of about 3 μm is disposed on the surface of the p-electrode 42. The gold-plated layer 46 and the heat sink 24 are connected to each other. Bonded with solder.
An n electrode 44 is formed on the back side of the n-GaAs substrate 28.
The third embodiment is a junction down (J-DOWN) assembly in which an epitaxial growth layer formed on the n-GaAs substrate 28 is disposed on the heat sink 24 side.
Next, the operation of the semiconductor laser according to the third embodiment will be described.
Since the Al composition ratio of the p-AlGaAs cladding layer 60 in the semiconductor laser device 54 is x = 0.90 and the Al composition ratio of the n-AlGaAs cladding layer 58 is x = 0.55, the refractive index is obtained from the equation (4). When the refractive index is calculated, the refractive index of the p-AlGaAs cladding layer 60 is 3.025, and the refractive index of the n-AlGaAs cladding layer 58 is 3.227.
Accordingly, considering that the undoped AlGaAs guide layer 32 and the undoped AlGaAs guide layer 36 are symmetrical in structure with respect to the refractive index and the layer thickness, the undoped AlGaAs active layer 34 is located on the opposite side of the heat sink 24 with respect to the AlGaAs active layer 34. Since the effective refractive indexes of the AlGaAs guide layer 32 and the n-AlGaAs cladding layer 58 are higher than the effective refractive indexes of the undoped AlGaAs guide layer 36 and the p-AlGaAs cladding layer 60 on the heat sink 24 side with respect to the AlGaAs active layer 34, the light The intensity distribution is expanded toward the n-AlGaAs cladding layer 58 on the side opposite to the heat sink 24 with respect to the AlGaAs active layer 34.

For this reason, the vertical beam divergence angle θv is reduced, and the aspect ratio is reduced.
In addition, since the beam diameter of the near-field image (NFP) is enlarged and the light density is reduced, end face deterioration at the time of high output is reduced, and the reliability of the LD in high output operation is increased.
In the semiconductor laser device 54, the Al composition ratio of the p-AlGaAs cladding layer 60 on the heat sink 24 side with respect to the AlGaAs active layer 34 is x = 0.90, and the side opposite to the heat sink 24 with respect to the AlGaAs active layer 34. Since the Al composition ratio of the n-AlGaAs cladding layer 58 is x = 0.55, the thermal conductivity of the p-AlGaAs cladding layer 60 is higher than the thermal conductivity of the n-AlGaAs cladding layer 58. I understand.
The thermal resistance of the semiconductor laser device 54 was calculated to be 9.06 ° C./W.
For comparison, the Al composition ratio of the p-AlGaAs cladding layer on the heat sink 24 side is set to x = 0.55 which is the same as the Al composition ratio of the n-AlGaAs cladding layer 58, and the layer thickness is the layer thickness of the p-AlGaAs cladding layer 60. When the thermal resistance was calculated with the same t = 1.5 μm and other specifications as the semiconductor laser device 54, the thermal resistance of Comparative Example 2 having this symmetrical refractive index structure was 9.54 ° C./W.
Therefore, the semiconductor laser device 54 according to this embodiment has a heat of about 5.0% as compared with the case of Comparative Example 2 in which the Al composition ratio of the p-AlGaAs cladding layer and the n-AlGaAs cladding layer is the same. The resistance can be reduced.

Modification 2
FIG. 8 is a cross-sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention. 8 is also basically the same as the configuration of FIG. 6, and therefore the cross-sectional position of FIG. 8 is also the VII-VII cross section of FIG.
The semiconductor laser device 70 shown in FIG. 8 is different from the semiconductor laser device 54 in that the p-AlGaAs cladding layer 60a has an Al composition ratio x = 0.90, a layer thickness t = 0.4 μm, and n The AlGaAs cladding layer 58a has an Al composition ratio of x = 0.55 and a layer thickness of t = 2.0 μm. Other configurations of the semiconductor laser device 70 are the same as those in the semiconductor laser device 54.
In both the semiconductor laser device 54 and the semiconductor laser device 70, the refractive indexes of the n-AlGaAs cladding layer 58 and the n-AlGaAs cladding layer 58a on the opposite side of the heat sink 24 with respect to the AlGaAs active layer 34 are higher than those of the AlGaAs active layer 34. Since the refractive index of the p-AlGaAs cladding layer 60 and the n-AlGaAs cladding layer 60a on the heat sink 24 side is higher than that of the heat sink 24, the light intensity distribution is n-AlGaAs cladding layer 58 and n-AlGaAs cladding layer on the opposite side of the heat sink 24. It will be enlarged to the 58a side. Therefore, even if the thickness of the p-AlGaAs cladding layer 60 on the heat sink 24 side is slightly reduced, the n-GaAs contact layer 40 is not affected optically. For this reason, in the semiconductor laser device 70, the p-AlGaAs cladding layer 60a has the Al composition ratio of x = 0.90, and the layer thickness is reduced to t = 0.4 μm.

In addition, the n-AlGaAs cladding layer 58a, which has a wider light intensity distribution, maintains the Al composition ratio x = 0.55, and the layer thickness t = t = is reduced in order to reduce the optical influence of the p-GaAs substrate 28. The thickness is 2.0 μm.
In the semiconductor laser device 70, the thermal conductivity of the p-AlGaAs cladding layer 60a is higher than the thermal conductivity of the n-AlGaAs cladding layer 58a, like the semiconductor laser device 54. In the semiconductor laser device 70, the p-AlGaAs cladding layer 60a is thinner than the p-AlGaAs cladding layer 60 of the semiconductor laser device 54, and the distance from the AlGaAs active layer 34 to the heat sink 24 is short. The heat conduction to the heat sink becomes easy and the heat dissipation effect can be enhanced.
The thermal resistance of the semiconductor laser device 70 is about 8.38 ° C./W, which is about 12.2% lower than the thermal resistance of Comparative Example 2 and about 7.5% lower than the thermal resistance of the semiconductor laser device 54. To do.

Modification 3
FIG. 9 is a sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention. 9 is basically the same as the configuration of FIG. 6, and therefore the cross-sectional position of FIG. 9 is also the VII-VII cross section of FIG.
The semiconductor laser device 74 shown in FIG. 9 is different from the semiconductor laser device 54 in that the n-AlGaAs cladding layer 58b has an Al composition ratio x = 0.90 and a layer thickness t = 1.5 μm. Thus, the n-AlGaAs cladding layer 58b and the p-AlGaAs cladding layer 60 have the same Al composition ratio and the same layer thickness, and the undoped AlGaAs guide layer 36b disposed on the heat sink 24 side with respect to the AlGaAs active layer 34. The Al composition ratio x = 0.80 and the layer thickness t = 50 nm, so that the undoped AlGaAs guide layer 32 (Al composition ratio x = 0.40, layer thickness on the opposite side of the heat sink 24 with respect to the AlGaAs active layer 34). (t = 94 nm). Other configurations of the semiconductor laser device 74 are the same as those in the semiconductor laser device 54.

In this semiconductor laser device 74, the n-AlGaAs cladding layer 58b and the p-AlGaAs cladding layer 60 have the same refractive index, but the undoped AlGaAs guide layer 36b disposed on the heat sink 24 side with respect to the AlGaAs active layer 34. Since the refractive index of the undoped AlGaAs guide layer 32 opposite to the heat sink 24 with respect to the AlGaAs active layer 34 is higher, the light intensity distribution is closer to the undoped AlGaAs guide layer 32 side opposite to the heat sink 24 with respect to the AlGaAs active layer 34. Expanding.
On the other hand, the thermal conductivity of the undoped AlGaAs guide layer 36b disposed on the heat sink 24 side with respect to the AlGaAs active layer 34 is the undoped AlGaAs guide layer opposite to the heat sink 24 with respect to the AlGaAs active layer 34. Since the heat conductivity is higher than 32, the heat generated in the vicinity of the AlGaAs active layer 34 is easily conducted toward the heat sink 24 and the heat dissipation is improved.
Since this semiconductor laser device 74 also has a laser resonator length L = 1000 μm, a laser element width W = 200 μm, and a stripe width S = 60 μm, the thermal resistance from the AlGaAs active layer 34 to the heat sink 24 is about 9.04 ° C./W. Compared with the thermal resistance of Comparative Example 2 of 9.54 ° C./W, the thermal resistance is reduced by about 5.2%.

Modification 4
FIG. 10 is a sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention. 10 is basically the same as the configuration of FIG. 6, and therefore, the cross-sectional position of FIG. 10 is also the VII-VII cross section of FIG. 6.
The semiconductor laser device 76 shown in FIG. 10 is different from the semiconductor laser device 54 in that the semiconductor laser device 54 is composed of one layer of the p-AlGaAs cladding layer 60, whereas the semiconductor laser device 76 is p. The p-AlGaAs first cladding layer 78a (Al composition ratio x = 0.55, layer thickness t = 0.3 μm) on the side close to the GaAs contact layer 40 and the p-AlGaAs second on the side close to the undoped AlGaAs guide layer 36 The cladding layer 78b (Al composition ratio x = 0.9, layer thickness t = 0.2 μm) is provided. Other configurations of the semiconductor laser device 76 are the same as those in the semiconductor laser device 54.

In this semiconductor laser device 76, since the refractive index of the p-AlGaAs second cladding layer 78b is lower than that of the n-AlGaAs cladding layer 58, the light intensity distribution is on the side of the undoped AlGaAs guide layer 32 opposite to the heat sink 24. Expand to.
On the other hand, regarding the thermal conductivity, the thermal conductivity of the p-AlGaAs second cladding layer 78b disposed on the heat sink 24 side with respect to the AlGaAs active layer 34 is n opposite to the heat sink 24 with respect to the AlGaAs active layer 34. The sum of the layer thicknesses of the p-AlGaAs second clad layer 78b and the p-AlGaAs first clad layer 78a higher than the thermal conductivity of the AlGaAs clad layer 58 and disposed on the heat sink 24 side is the n-AlGaAs clad layer Since the thickness is smaller than 58, the heat generated in the vicinity of the AlGaAs active layer 34 is easily conducted toward the heat sink 24, and the heat dissipation is improved.
Since this semiconductor laser device 76 also has a laser resonator length L = 1000 μm, a laser element width W = 200 μm, and a stripe width S = 60 μm, the thermal resistance from the AlGaAs active layer 34 to the heat sink 24 is about 9.44 ° C./W. Compared with the thermal resistance of 9.54 ° C./W in Comparative Example 2, it is reduced by about 1%.

As described above, in the semiconductor laser device according to this embodiment, the refractive index of the p-AlGaAs layer disposed on the heat sink side with respect to the AlGaAs active layer is disposed on the side opposite to the heat sink with respect to the AlGaAs active layer. Since the refractive index is lower than the refractive index of the n-AlGaAs layer provided, the light intensity distribution of the semiconductor laser is expanded to the n-AlGaAs layer disposed on the side opposite to the heat dissipator, and the beam diameter is expanded to increase the light The density is reduced, the end face deterioration during high output is less likely to occur, high output operation is possible, the aspect ratio is small, and the heat of the p-AlGaAs layer disposed on the radiator side with respect to the AlGaAs active layer. By making the conduction better than the heat conduction of the n-AlGaAs layer disposed on the opposite side of the heat sink with respect to the AlGaAs active layer, the heat generated by the semiconductor laser is transferred to the heat sink. It is easier to guide.
In addition, since the light intensity distribution is expanded to the n-AlGaAs cladding layer side opposite to the radiator, the thickness of the p-AlGaAs cladding layer on the heat sink side can be reduced, Heat conduction can be made easier and the heat dissipation effect can be enhanced.
Therefore, it is possible to configure a semiconductor laser device capable of high output operation and easily conducting heat generated by the high output operation to the heat radiating body. As a result, a highly reliable semiconductor laser with high output operation can be provided.

Embodiment 4 FIG.
FIG. 11 is a cross-sectional view of a semiconductor laser device according to an embodiment of the present invention.
Also in the fourth embodiment, the basic configuration of the semiconductor laser device is the same as that of FIG. 3, and the semiconductor laser device according to this embodiment includes two p-side guide layers and two n-side guide layers. The only difference from the semiconductor laser device of FIG. 3 is that the cross-sectional position of FIG. 11 is also the same as the IV-IV cross section of FIG.
The semiconductor laser device according to this embodiment is also junction-up (J-UP) assembled.
Furthermore, in the semiconductor laser device according to this embodiment, the cladding layer is made of AlGaAs or AlGaInP containing Al, but other layers (active layer, guide layer, contact layer, substrate, etc.) substantially contain Al. There is no Al-free structure.
In FIG. 11, the semiconductor laser device 80 is formed of a semiconductor laser element 22 and a heat sink 24. The semiconductor laser device 80 also has, for example, a laser resonator length L = 1000 μm, a laser element width W = 200 μm, and a stripe width S = 60 μm. The thickness of the heat sink 24 is 0.3 mm.

The semiconductor laser device 22 includes an n-GaAs substrate 28 and an n-AlGaAs cladding layer 30 (Al composition ratio x = 0.90, layer thickness) on the surface of the n-GaAs substrate 28 sequentially from the n-GaAs substrate 28 side. t = 1.5 μm), undoped InGaP guide layer 82 (Ga composition ratio y = 0.51, layer thickness t = 120 nm), undoped InGaAsP guide layer 84 (Ga composition ratio y = 0.63, As composition ratio z = 0) .25, layer thickness t = 20 nm), InGaAsP active layer 86 (Ga composition ratio y = 0.87, As composition ratio z = 0.74, layer thickness t = 16 nm), undoped InGaAsP guide layer 88 (Ga composition ratio y) = 0.63, As composition ratio z = 0.25, layer thickness t = 20 nm), undoped InGaP guide layer 90 (Ga composition ratio y = 0.51, layer thickness t = 120 nm), p-Al aAs cladding layer 38 (Al composition ratio x = 0.55, and its thickness t = 1.5μm), p-GaAs contact layer 40 is disposed. The proton injection regions 26 for current confinement are disposed on both sides of the stripe, which is a region where current flows in the center of the element width. In the depth direction of the proton injection region 26, the p-GaAs contact layer 40 is disposed. Protons are implanted from the surface to the middle of the thickness of the p-AlGaAs cladding layer 38. Further, a p-electrode 42 is disposed on the surface of the p-GaAs contact layer 40.
An n electrode 44 is formed on the back side of the n-GaAs substrate 28, and a gold plating layer 46 having a thickness of about 3 μm is disposed on the surface of the n electrode. The gold plating layer 46 and the heat sink 24 are soldered together. Glued.

The fourth embodiment is a junction up (J-UP) assembly in which the n-GaAs substrate 28 is disposed on the heat sink 24 side.
In this semiconductor laser device 80, the undoped InGaP guide layer 82, the undoped InGaAsP guide layer 84, the undoped InGaAsP guide layer 88, and the undoped InGaP guide layer 90 are symmetrical in structure with the InGaAsP active layer 86 interposed therebetween. It has become. Since the Al composition ratio of the n-AlGaAs cladding layer 30 in the semiconductor laser device 80 is x = 0.90 and the Al composition ratio of the p-AlGaAs cladding layer 38 is x = 0.55, the formula (4) When the refractive index is calculated from the above, the refractive index of the n-AlGaAs cladding layer 30 is 3.025, and the refractive index of the p-AlGaAs cladding layer 38 is 3.227.
Therefore, it is considered that the undoped InGaP guide layer 82, the undoped InGaAsP guide layer 84, the InGaAsP active layer 86, the undoped InGaAsP guide layer 88, and the undoped InGaP guide layer 90 have a symmetric structure with respect to the refractive index and the layer thickness with the InGaAsP active layer 86 interposed therebetween. Then, the effective refractive indexes of the undoped InGaAsP guide layer 88, the undoped InGaP guide layer 90, and the p-AlGaAs cladding layer 38 on the opposite side to the heat sink 24 with respect to the InGaAsP active layer 86 are on the heat sink 24 side with respect to the InGaAsP active layer 86. The light intensity distribution is opposite to that of the heat sink 24 because it is higher than the effective refractive index of a certain undoped InGaP guide layer 82, undoped InGaAsP guide layer 84 and n-AlGaAs cladding layer 30. It extends to the p-AlGaAs cladding layer 38 side in.
For this reason, the vertical beam divergence angle θv is reduced, and the aspect ratio is reduced.

Further, when the vertical beam divergence angle θv is reduced, the beam diameter of the near-field image is enlarged and the light density is reduced, so that end face deterioration at high output is reduced and the reliability of the LD in high output operation is increased. .
Further, when the light intensity distribution expands to the p-AlGaAs cladding layer 38 side opposite to the heat sink 24, free carrier absorption due to the n-AlGaAs cladding layer 30 is reduced, and light absorption is reduced. Slope efficiency is improved and high output operation can be performed.
On the other hand, in the semiconductor laser device 80, the Al composition ratio of the n-AlGaAs cladding layer 30 on the heat sink 24 side with respect to the InGaAsP active layer 86 is x = 0.90. Since the Al composition ratio of the p-AlGaAs cladding layer 38 on the opposite side is x = 0.55, the thermal conductivity of the n-AlGaAs cladding layer 30 is higher than the thermal conductivity of the p-AlGaAs cladding layer 38. Become. Therefore, the heat generated in the vicinity of the InGaAsP active layer 86 is easily conducted to the heat sink 24 and is excellent in heat dissipation.

Modification 5
FIG. 12 is a cross-sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention. The cross-sectional position in FIG. 12 is also the IV-IV cross section in FIG.
The semiconductor laser device 96 shown in FIG. 12 is different from the semiconductor laser device 80 in that an undoped InGaP guide layer 82, an undoped InGaAsP guide layer 84, and an undoped InGaAsP guide layer 88 are sandwiched between an InGaAsP active layer 86 and an InGaAsP active layer 86. The n-AlGaAs cladding layer 30a has an Al composition ratio of x = 0.90 and a layer thickness of t = 0.4 μm while the material configuration and the layer thickness of the n-AlGaAs cladding layer 30a are the same as those of the semiconductor laser device 80. P-AlGaAs cladding layer 38a has an Al composition ratio of x = 0.55 and a layer thickness of t = 2.0 μm. Other configurations of the semiconductor laser device 96 are the same as those in the semiconductor laser device 80.
Accordingly, in the semiconductor laser device 96, as in the first modification, the layer thickness of the n-AlGaAs cladding layer 30a is smaller than the layer thickness of the n-AlGaAs cladding layer 30 of the semiconductor laser device 80, and from the InGaAsP active layer 86 to the heat sink 24. Since the distance is short, the heat conduction to the heat sink is facilitated and the heat dissipation effect can be enhanced.

Modification 6
FIG. 13 is a cross-sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention. The cross-sectional position in FIG. 13 is also the IV-IV cross section in FIG.
In FIG. 13, the semiconductor laser device 100 is formed of a semiconductor laser element 22 and a heat sink 24. The semiconductor laser device 100 also has, for example, a laser resonator length L = 1000 μm, a laser element width W = 200 μm, and a stripe width S = 60 μm. The thickness of the heat sink 24 is 0.3 mm.
The difference between the semiconductor laser device 100 and the semiconductor laser device 80 is that the semiconductor laser device 80 is provided with the n-AlGaAs cladding layer 30 and the p-AlGaAs cladding layer 38, whereas the semiconductor laser device 100 has n. -AlGaInP cladding layer 102 (Al composition ratio l = 0.36, Ga composition ratio m = 0.15, In composition ratio n = 0.49, layer thickness t = 1.5 μm) and p-AlGaInP cladding layer 104 (Al Composition ratio l = 0.255, Ga composition ratio m = 0.255, In composition ratio n = 0.49, and layer thickness t = 1.5 μm). Other configurations are the same as those of the semiconductor laser element 80.
In this semiconductor laser device 100, the undoped InGaP guide layer 82, the undoped InGaAsP guide layer 84, the InGaAsP active layer 86, the undoped InGaAsP guide layer 88, and the undoped InGaP guide layer 90 are composed of materials and layers sandwiching the InGaAsP active layer 86. The thickness is symmetrical.

H. Tanaka, Y. Kawamura, and H. Asahi, “Refractive indices of In _0.49 Ga _0.51-x Al _x P lattice matched to GaAs”, J. App. Phys., Vol. 59, No. 3, 1 February 1986 , pp. 985-986 show that the refractive index decreases as the Al composition ratio increases in AlGaInP.
The Al composition ratio in the n-AlGaInP cladding layer 102 in the semiconductor laser device 100 is l = 0.36, and the Al composition ratio in the p-AlGaInP cladding layer 104 is l = 0.255. For this reason, the refractive index of the p-AlGaInP cladding layer 104 is higher than the refractive index of the n-AlGaInP cladding layer 102.
Therefore, the undoped InGaP guide layer 82, the undoped InGaAsP guide layer 84, the InGaAsP active layer 86, the undoped InGaAsP guide layer 88, and the undoped InGaP guide layer 90 have a symmetric structure with the material structure and the layer thickness sandwiching the InGaAsP active layer 86. Therefore, the effective refractive index of the undoped InGaAsP guide layer 88, the undoped InGaP guide layer 90, and the p-AlGaInP cladding layer 104 disposed on the opposite side of the heat sink 24 with respect to the InGaAsP active layer 86 is InGaAsP. The effective refractive index of the undoped InGaP guide layer 82, the undoped InGaAsP guide layer 84, and the n-AlGaInP cladding layer 102 disposed on the heat sink 24 side with respect to the active layer 86. Kunar.

Accordingly, the light intensity distribution is expanded toward the p-AlGaInP cladding layer 104 on the side opposite to the heat sink 24.
For this reason, the vertical beam divergence angle θv is reduced, and the aspect ratio is reduced.
Further, when the vertical beam divergence angle θv is reduced, the beam diameter of the near-field image is enlarged and the light density is reduced, so that end face deterioration at high output is reduced and the reliability of the LD in high output operation is increased. .
Furthermore, when the light intensity distribution expands to the p-AlGaInP cladding layer 104 side opposite to the heat sink 24, free carrier absorption due to the n-AlGaInP cladding layer 102 is reduced, and light absorption is reduced. Slope efficiency is improved and high output operation can be performed.

Also, H. Fujii, Y. Ueno, and K. Endo, “Effect of thermal thermally on the catastrophic optical damage power density of AlGaInP laser diodes”, Appl. Phys. Lett. Vol. 62, no. 17, 26 April 1993 Shows that the thermal conductivity increases as the Al composition ratio increases in AlGaInP.
The Al composition ratio in the n-AlGaInP cladding layer 102 in the semiconductor laser device 100 is l = 0.36, and the Al composition ratio in the p-AlGaInP cladding layer 104 is l = 0.255. For this reason, the thermal conductivity of the n-AlGaInP cladding layer 102 disposed on the heat sink 24 side with respect to the InGaAsP active layer 86 is p − disposed on the opposite side of the heat sink 24 with respect to the InGaAsP active layer 86. It becomes higher than the thermal conductivity of the AlGaInP cladding layer 104. For this reason, the heat generated in the vicinity of the InGaAsP active layer 86 is easily conducted to the heat sink 24 and is excellent in heat dissipation.

Modification 7
FIG. 14 is a cross-sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention. The cross-sectional position in FIG. 14 is also the IV-IV cross section in FIG.
The semiconductor laser device 110 shown in FIG. 14 is different from the semiconductor laser device 100 in that an undoped InGaP guide layer 82, an undoped InGaAsP guide layer 84, and an undoped InGaAsP guide layer 88 are sandwiched between the InGaAsP active layer 86 and the InGaAsP active layer 86. The undoped InGaP guide layer 90 has the same material structure and layer thickness as the semiconductor laser device 100, and the n-AlGaInP cladding layer 102a has an Al composition ratio l = 0.36, a Ga composition ratio m = 0.15, In The composition ratio n = 0.49, the layer thickness t = 0.4 μm, the p-AlGaInP cladding layer 104a has an Al composition ratio l = 0.255, a Ga composition ratio m = 0.255, an In composition ratio n = 0.49, and the layer thickness was t = 2.0 μm. Other configurations of the semiconductor laser device 110 are the same as those in the semiconductor laser device 100.
Therefore, in the semiconductor laser device 110, the layer thickness of the n-AlGaInP cladding layer 102 a is thinner than the layer thickness of the n-AlGaInP cladding layer 102 of the semiconductor laser device 100 for the same reason as in the first modification, and the heat sink from the InGaAsP active layer 86. Since the distance to 24 is short, heat conduction to the heat sink is facilitated, and the heat dissipation effect can be enhanced.
As described above, in the semiconductor laser device according to this embodiment, the cladding layer is made of AlGaAs or AlGaInP containing Al, but the other layers (active layer, guide layer, contact layer, substrate, etc.) are made of Al. The semiconductor laser device having an Al-free structure which does not substantially include the same effects as those of the second embodiment.

Embodiment 5. FIG.
FIG. 15 is a sectional view of a semiconductor laser device according to an embodiment of the present invention.
Also in the fifth embodiment, the basic configuration of the semiconductor laser device is the same as that of FIG. 6, and the semiconductor laser device according to this embodiment includes two p-side guide layers and two n-side guide layers. The only difference from the semiconductor laser device of FIG. 6 is that the cross-sectional position of FIG. 15 is the same cross-sectional position as the VII-VII cross section of FIG.
The semiconductor laser device according to this embodiment is also junction down (J-DOWN) assembly.
Furthermore, in the semiconductor laser device according to this embodiment, the cladding layer is made of AlGaAs or AlGaInP containing Al, but other layers (active layer, guide layer, contact layer, substrate, etc.) substantially contain Al. There is no Al-free structure.
In FIG. 15, the semiconductor laser device 114 is formed of a semiconductor laser element 56 and a heat sink 24. The semiconductor laser device 114 also has, for example, a laser resonator length L = 1000 μm, a laser element width W = 200 μm, and a stripe width S = 60 μm. The thickness of the heat sink 24 is 0.3 mm.

The semiconductor laser element 56 of the semiconductor laser device 114 includes an n-GaAs substrate 28 and an n-AlGaAs cladding layer 58 as a second semiconductor layer on the surface of the n-GaAs substrate 28 in order from the n-GaAs substrate 28 side. (Al composition ratio x = 0.55, layer thickness t = 1.5 μm), undoped InGaP guide layer 82 (Ga composition ratio y = 0.51, layer thickness t = 120 nm), undoped InGaAsP guide layer 84 (Ga composition ratio) y = 0.63, As composition ratio z = 0.25, layer thickness t = 20 nm), InGaAsP active layer 86 (Ga composition ratio y = 0.87, As composition ratio z = 0.74, layer thickness t = 16 nm) ), Undoped InGaAsP guide layer 88 (Ga composition ratio y = 0.63, As composition ratio z = 0.25, layer thickness t = 20 nm), undoped InGaP guide layer 90 (Ga composition) y = 0.51, layer thickness t = 120 nm), p-AlGaAs cladding layer 60 (Al composition ratio x = 0.9, layer thickness t = 1.5 μm) as a first semiconductor layer, p-GaAs contact layer 40 is disposed.
The proton injection regions 26 for current confinement are disposed on both sides of the stripe, which is a region where current flows in the center of the element width. In the depth direction of the proton injection region 26, the p-GaAs contact layer 40 is disposed. The protons are implanted from the surface of the p-AlGaAs to the middle of the thickness of the p-AlGaAs cladding layer 60.

Further, a p-electrode 42 is disposed on the surface of the p-GaAs contact layer 40, and a gold-plated layer 46 having a thickness of about 3 μm is disposed on the surface of the p-electrode 42. The gold-plated layer 46 and the heat sink 24 are connected to each other. Bonded with solder.
In this semiconductor laser device 114, the undoped InGaP guide layer 82, the undoped InGaAsP guide layer 84, the undoped InGaAsP guide layer 88, and the undoped InGaP guide layer 90 have a symmetric structure with the material configuration and the layer thickness sandwiching the InGaAsP active layer 86. It has become.
The Al composition ratio of the n-AlGaAs cladding layer 58 in the semiconductor laser device 114 is x = 0.55, and the Al composition ratio of the p-AlGaAs cladding layer 60 is x = 0.9. From this, the refractive index of the n-AlGaAs cladding layer 58 is 3.227, and the refractive index of the p-AlGaAs cladding layer 60 is 3.025.
Accordingly, considering that the undoped InGaP guide layer 82, the undoped InGaAsP guide layer 84, the undoped InGaAsP guide layer 88, and the undoped InGaP guide layer 90 have a symmetrical material structure and layer thickness with the InGaAsP active layer 86 interposed therebetween. The effective refractive indexes of the undoped InGaP guide layer 82, the undoped InGaAsP guide layer 84, and the n-AlGaAs cladding layer 58 on the opposite side of the heat sink 24 with respect to the InGaAsP active layer 86 are on the heat sink 24 side with respect to the InGaAsP active layer 86. Since the effective refractive index of the undoped InGaAsP guide layer 88, the undoped InGaP guide layer 90, and the p-AlGaAs cladding layer 60 is higher, the light intensity distribution is on the side opposite to the heat sink 24. So that extends to the n-AlGaAs cladding layer 58 side. For this reason, the vertical beam divergence angle θv is reduced, and the aspect ratio is reduced.

Further, when the vertical beam divergence angle θv is reduced, the beam diameter of the near-field image is enlarged and the light density is reduced, so that end face deterioration at high output is reduced and the reliability of the LD in high output operation is increased. .
On the other hand, in the semiconductor laser device 114, the Al composition ratio of the p-AlGaAs cladding layer 60 on the heat sink 24 side with respect to the InGaAsP active layer 86 is x = 0.90. Since the Al composition ratio of the n-AlGaAs cladding layer 58 on the opposite side is x = 0.55, the thermal conductivity of the p-AlGaAs cladding layer 60 is higher than the thermal conductivity of the n-AlGaAs cladding layer 58. Become. Therefore, the heat generated in the vicinity of the InGaAsP active layer 86 is easily conducted to the heat sink 24 and is excellent in heat dissipation.

Modification 8
FIG. 16 is a sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention. The cross-sectional position in FIG. 16 is also the same cross-sectional position as the VII-VII cross section in FIG.
The semiconductor laser device of this modification 8 is also junction down (J-DOWN) assembly.
The semiconductor laser device 120 shown in FIG. 16 differs from the semiconductor laser device 114 in that the undoped InGaP guide layer 82, the undoped InGaAsP guide layer 84, and the undoped InGaAsP guide layer 88 are sandwiched between the InGaAsP active layer 86 and the InGaAsP active layer 86. The p-AlGaAs cladding layer 60a has an Al composition ratio of x = 0.90 and a layer thickness of t = 0.4 μm, while the material configuration and the layer thickness of the p-AlGaAs cladding layer 60a are the same as those of the semiconductor laser device 80. The n-AlGaAs cladding layer 58a has an Al composition ratio of x = 0.55 and a layer thickness of t = 2.0 μm. The other configuration of the semiconductor laser device 120 is the same as that in the semiconductor laser device 114.
Accordingly, in the semiconductor laser device 120, the layer thickness of the p-AlGaAs cladding layer 60 a is thinner than the layer thickness of the p-AlGaAs cladding layer 60 of the semiconductor laser device 114, as in the second modification, and from the AlGaAs active layer 34 to the heat sink 24. Therefore, the heat conduction to the heat sink becomes easier than the semiconductor laser device 114, and the heat dissipation effect can be enhanced.

Modification 9
FIG. 17 is a sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention. The cross-sectional position in FIG. 17 is also the same as the VII-VII cross section in FIG.
In FIG. 17, the semiconductor laser device 124 is formed of a semiconductor laser element 56 and a heat sink 24. The semiconductor laser device 124 also has, for example, a laser resonator length L = 1000 μm, a laser element width W = 200 μm, and a stripe width S = 60 μm. The thickness of the heat sink 24 is 0.3 mm.
The difference between the semiconductor laser device 124 and the semiconductor laser device 114 is that the semiconductor laser device 114 is provided with the n-AlGaAs cladding layer 60 and the p-AlGaAs cladding layer 58, whereas the semiconductor laser device 124 has n. -AlGaInP cladding layer 126 (Al composition ratio l = 0.255, Ga composition ratio m = 0.255, In composition ratio n = 0.49, layer thickness t = 1.5 μm) and p-AlGaInP cladding layer 128 (Al Composition ratio l = 0.36, Ga composition ratio m = 0.15, In composition ratio n = 0.49, and layer thickness t = 1.5 μm). Other configurations are the same as those of the semiconductor laser device 114.
In this semiconductor laser device 124, the undoped InGaP guide layer 82, the undoped InGaAsP guide layer 84, the undoped InGaAsP guide layer 88, and the undoped InGaP guide layer 90 have a symmetric structure with the material configuration and the layer thickness sandwiching the InGaAsP active layer 86. It has become.

  When the Al composition ratio increases in AlGaInP, the refractive index decreases, so that the refractive index of the n-AlGaInP cladding layer 126 becomes higher than that of the p-AlGaInP cladding layer 128. Therefore, it is considered that the undoped InGaP guide layer 82, the undoped InGaAsP guide layer 84, the undoped InGaAsP guide layer 88, and the undoped InGaP guide layer 90 have a symmetric structure with respect to the material structure and layer thickness with the InGaAsP active layer 86 interposed therebetween. Then, the effective refractive index of the undoped InGaP guide layer 82, the undoped InGaAsP guide layer 84, and the n-AlGaInP cladding layer 126 disposed on the opposite side of the heat sink 24 with respect to the InGaAsP active layer 86 is smaller than that of the InGaAsP active layer 86. Thus, the effective refractive index of the undoped InGaAsP guide layer 88, the undoped InGaP guide layer 90, and the p-AlGaInP cladding layer 128 disposed on the heat sink 24 side is higher.

Therefore, the light intensity distribution is expanded to the n-AlGaInP cladding layer 126 side on the side opposite to the heat sink 24. For this reason, the vertical beam divergence angle θv is reduced, and the aspect ratio is reduced.
Further, when the vertical beam divergence angle θv is reduced, the beam diameter of the near-field image is enlarged and the light density is reduced, so that end face deterioration at high output is reduced and the reliability of the LD in high output operation is increased. .
Further, since the thermal conductivity of AlGaInP increases as the Al composition ratio increases, the thermal conductivity of the p-AlGaInP cladding layer 128 disposed on the heat sink 24 side with respect to the InGaAsP active layer 86 is higher than that of the InGaAsP active layer 86. On the other hand, the thermal conductivity of the n-AlGaInP cladding layer 126 disposed on the opposite side of the heat sink 24 is higher. For this reason, the heat generated in the vicinity of the InGaAsP active layer 86 is easily conducted to the heat sink 24 and is excellent in heat dissipation.

Modification 10
FIG. 18 is a cross-sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention. The cross-sectional position in FIG. 18 is also the same cross-sectional position as the VII-VII cross section in FIG.
The semiconductor laser device 130 shown in FIG. 18 differs from the semiconductor laser device 124 in that an undoped InGaP guide layer 82, an undoped InGaAsP guide layer 84, and an undoped InGaAsP guide layer 88 are sandwiched between an InGaAsP active layer 86 and an InGaAsP active layer 86. The undoped InGaP guide layer 90 has the same material configuration and layer thickness as the semiconductor laser device 124, and the p-AlGaInP cladding layer 128a has an Al composition ratio l = 0.36, a Ga composition ratio m = 0.15, In The composition ratio n = 0.49, the layer thickness t = 0.4 μm, the n-AlGaInP cladding layer 126a has an Al composition ratio l = 0.255, a Ga composition ratio m = 0.255, an In composition ratio n = 0.49, and the layer thickness was t = 2.0 μm. The other configuration of the semiconductor laser device 130 is the same as that in the semiconductor laser device 124.
Therefore, in the semiconductor laser device 130, the layer thickness of the p-AlGaInP cladding layer 128 a is thinner than the layer thickness of the p-AlGaInP cladding layer 128 of the semiconductor laser device 124 for the same reason as in the second modification, and the heat sink from the InGaAsP active layer 86. Since the distance to 24 is short, the heat conduction to the heat sink becomes easier than the semiconductor laser device 124, and the heat dissipation effect can be enhanced.
As described above, in the semiconductor laser device according to this embodiment, the cladding layer is made of AlGaAs or AlGaInP containing Al, but the other layers (active layer, guide layer, contact layer, substrate, etc.) are made of Al. The semiconductor laser device having a substantially Al-free structure has the same effects as those of the third embodiment.

Embodiment 6 FIG.
FIG. 19 is a cross-sectional view of a semiconductor laser device according to an embodiment of the present invention.
In FIG. 19, a semiconductor laser device 134 is a red semiconductor laser device having a ridge waveguide structure with an oscillation wavelength of about 650 nm, and is formed of a semiconductor laser element 136 and a heat sink 24.
In FIG. 19, a semiconductor laser device 136 includes an n-GaAs substrate 28 and an n-AlGaInP cladding layer 138 (second semiconductor layer) on the surface of the n-GaAs substrate 28 sequentially from the n-GaAs substrate 28 side. Al composition ratio l = 0.31, Ga composition ratio m = 0.20, In composition ratio n = 0.49, layer thickness t = 2.0 μm), undoped AlGaInP guide layer 140 (Al Composition ratio l = 0.23, Ga composition ratio m = 0.28, In composition ratio n = 0.49, layer thickness t = 100 nm), undoped compression strained GaInP active layer 142 (Ga composition ratio m = 0.44) In composition ratio n = 0.56, layer thickness t = 10 nm), undoped AlGaInP guide layer 144 as the third semiconductor layer (Al composition ratio l = 0.23, Ga composition ratio m = 0.28, In group) Ratio n = 0.49, layer thickness t = 100 nm), p-AlGaInP cladding layer 146 as the first semiconductor layer (Al composition ratio l = 0.36, Ga composition ratio m = 0.15, In composition ratio 0) .49, layer thickness t = 1.0 μm), a p-GaAs contact layer 148 is provided.

The p-AlGaInP cladding layer 146 and the p-GaAs contact layer 148 form a ridge waveguide, and an insulating film 152 having an opening 150 at the top of the ridge waveguide is formed on the surface of the p-GaAs contact layer 148. Yes. A p-electrode 42 is disposed on the opening 150 and the insulating film 152, and an n-electrode 44 is disposed on the back side of the n-GaAs substrate 28. A gold plating layer 46 is disposed on the surface of the p-electrode 42, and the semiconductor laser element 136 is joined to the heat sink 24 by solder via the gold plating layer 46.
Although the semiconductor laser device 134 according to this embodiment is also a junction down (J-DOWN) assembly, it may be a junction up (J-UP) assembly.
In the semiconductor laser device 134, the refractive index of the n-AlGaInP cladding layer 138 is higher than that of the p-AlGaInP cladding layer 146, so that it is disposed on the opposite side of the heat sink 24 with respect to the undoped compressive strain GaInP active layer 142. The effective refractive indexes of the undoped AlGaInP guide layer 140 and the n-AlGaInP cladding layer 138 are the same as those of the undoped AlGaInP guide layer 144 and the p-AlGaInP cladding layer 146 disposed on the heat sink 24 side with respect to the undoped compression strained GaInP active layer 142. Since the refractive index becomes higher than the refractive index, the light intensity distribution mainly expands to the n-AlGaInP cladding layer 138 side disposed on the side opposite to the heat sink 24. For this reason, the vertical beam divergence angle θv is reduced, and the horizontal beam divergence angle θh is not particularly changed. Therefore, the aspect ratio, which is the ratio of the vertical beam divergence angle θv to the horizontal beam divergence angle θh, is reduced.

Further, when the vertical beam divergence angle θv is reduced, the beam diameter of the near-field image is enlarged and the light density is reduced, so that end face deterioration at high output is reduced and the reliability of the LD in high output operation is increased. .
Since the thermal conductivity of AlGaInP increases as the Al composition ratio increases, the thermal conductivity of the p-AlGaInP cladding layer 146 disposed on the heat sink 24 side is n − disposed on the opposite side of the heat sink 24. The thermal conductivity of the AlGaInP cladding layer 138 is higher than that of the AlGaInP clad layer 138, and heat generated in the vicinity of the undoped compressive strain GaInP active layer 142 is easily conducted to the heat sink 24 side so that the heat dissipation effect is high.
Furthermore, the light intensity distribution mainly expands toward the n-AlGaInP cladding layer 138 disposed on the side opposite to the heat sink 24. Therefore, even if the thickness of the p-AlGaInP cladding layer 146 disposed on the heat sink 24 side is reduced to 1.0 μm, the p-GaAs contact layer 148 is not optically affected. On the other hand, the n-AlGaInP cladding layer 138 disposed on the side where the light intensity distribution is enlarged has a layer thickness of 2.0 μm in order to reduce the optical influence of the n-GaAs substrate 28. Therefore, the distance from the undoped compressive strain GaInP active layer 142 to the heat sink 24 can be shortened, and the heat dissipation effect can be further enhanced.

Modification 11
FIG. 20 is a sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention.
In FIG. 20, the semiconductor laser device 156 is different from the semiconductor laser device 134 in the following points.
In the semiconductor laser device 134, the n-AlGaInP cladding layer 138 and the p-AlGaInP cladding layer 146 have an asymmetric structure with respect to the undoped compression strained GaInP active layer 142, and the undoped AlGaInP guide layer 140 and the undoped AlGaInP guide layer 144 are the same. The guide layer was made symmetrical with respect to the undoped compression strained GaInP active layer 142 with the same layer thickness in the material configuration.
However, in this semiconductor laser device 156, the n-AlGaInP cladding layer 138 and the p-AlGaInP cladding layer 146 have an asymmetric structure with respect to the undoped compression strained GaInP active layer 142, and further, the undoped AlGaInP guide layer 140 and the undoped AlGaInP guide layer. 144 a is an asymmetric structure with respect to the undoped compressive strain GaInP active layer 142.
That is, the undoped AlGaInP guide layer 144a has an Al composition ratio l = 0.25, a Ga composition ratio m = 0.26, an In composition ratio n = 0.49, and a layer thickness t = 70 nm.
Thus, the semiconductor laser device 156 enables a higher heat dissipation effect than the semiconductor laser device 134.
In this modification, both the guide layer and the clad layer have an asymmetric structure, but it goes without saying that a corresponding heat dissipation effect can be achieved even if the clad layer is a symmetric structure and only the guide layer is an asymmetric structure.

Modification 12
FIG. 21 is a cross-sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention.
A semiconductor laser device 160 in FIG. 21 is a semiconductor laser device having a ridge waveguide structure with an oscillation wavelength of about 1480 nm, and is formed of a semiconductor laser element 162 and a heat sink 24.
In FIG. 21, a semiconductor laser element 162 includes an n-InP substrate 164 and an n-InGaAsP cladding layer 166 (second semiconductor layer) on the surface of the n-InP substrate 164 in order from the n-InP substrate 164 side. Band gap wavelength λg = 0.99 μm, layer thickness t = 2.0 μm), undoped InGaAsP guide layer 168 as a fourth semiconductor layer (band gap wavelength λg = 1.08 μm, layer thickness t = 150 nm), undoped InGaAsP activity Layer 170 (bandgap wavelength λg = 1.48 μm, layer thickness t = 10 nm), undoped InGaAsP guide layer 172 as a third semiconductor layer (bandgap wavelength λg = 1.08 μm, layer thickness t = 150 nm), first P-InP cladding layer 174 (layer thickness t = 1.0 μm) as a semiconductor layer, p-InP contour Coat layer 176 is disposed. The p-InP cladding layer 174 and the p-InP contact layer 176 form a ridge waveguide, and an insulating film 152 having an opening 150 at the top of the ridge is formed on the surface of the p-InP contact layer 176. A p-electrode 42 is disposed on the opening 150 and the insulating film 152, and an n-electrode 44 is disposed on the back side of the n-InP substrate 164. A gold plating layer 46 is disposed on the surface of the p-electrode 42, and the semiconductor laser element 162 is joined to the heat sink 24 by solder via the gold plating layer 46.

In the semiconductor laser device 160, the refractive index of the n-InGaAsP cladding layer 166 is higher than that of the p-InP cladding layer 174. Accordingly, the effective refractive index of the undoped InGaAsP guide layer 168 and the n-InGaAsP cladding layer 166 disposed on the opposite side of the heat sink 24 with respect to the undoped InGaAsP active layer 170 is disposed on the heat sink 24 side with respect to the undoped InGaAsP active layer 170. Since the effective refractive index of the undoped InGaAsP guide layer 172 and the p-InP clad layer 174 becomes higher, the light intensity distribution mainly expands to the n-InGaAsP clad layer 166 side disposed on the side opposite to the heat sink 24. It will be. For this reason, the vertical beam divergence angle θv is reduced, and the horizontal beam divergence angle θh is not particularly changed. Therefore, the aspect ratio, which is the ratio of the vertical beam divergence angle θv to the horizontal beam divergence angle θh, is reduced.
Further, when the vertical beam divergence angle θv is reduced, the beam diameter of the near-field image is enlarged and the light density is reduced, so that end face deterioration at high output is reduced and the reliability of the LD in high output operation is increased. .
The thermal conductivity of the p-InP cladding layer 174 having a binary composition disposed on the heat sink 24 side is the thermal conductivity of the n-InGaAsP cladding layer 166 having a quaternary composition disposed on the opposite side of the heat sink 24. The heat conductivity is higher than that of the undoped InGaAsP active layer 170, and the heat dissipation effect is easily increased.
Furthermore, the light intensity distribution mainly expands to the n-InGaAsP cladding layer 166 side disposed on the side opposite to the heat sink 24. Since the contact layer is also p-InP, the p-InP contact layer 176 is optically affected even if the p-InP clad layer 174 disposed on the heat sink 24 side is made as thin as 1.0 μm. There is no. On the other hand, the n-InGaAsP clad layer 166 disposed on the side where the light intensity distribution is enlarged has a thickness of 2.0 μm in order to reduce the optical influence of the n-InP substrate 164. Therefore, the distance from the undoped InGaAsP active layer 170 to the heat sink 24 can be shortened, and the heat dissipation effect can be further enhanced.

Modification 13
FIG. 22 is a cross-sectional view of a modification of the semiconductor laser device according to one embodiment of the present invention.
A semiconductor laser device 180 in FIG. 22 is a semiconductor laser device having a ridge waveguide structure with an oscillation wavelength of about 410 nm, and is formed of a semiconductor laser element 182 and a heat sink 24.
In FIG. 22, a semiconductor laser element 182 includes an n-GaN substrate 184 and an n-AlGaN cladding layer 186 as a second semiconductor layer on the surface of the n-GaN substrate 184 in order from the n-GaN substrate 184 side. Al composition ratio x = 0.9, layer thickness t = 2.0 μm), undoped GaN guide layer 188 (layer thickness t = 100 nm) as the fourth semiconductor layer, undoped InGaN active layer 190 (In composition ratio n = 0) .1, layer thickness t = 10 nm), undoped GaN guide layer 192 (layer thickness t = 100 nm) as the third semiconductor layer, p-AlGaN cladding layer 194 as the first semiconductor layer (Al composition ratio x = 0) .4, layer thickness t = 1.0 μm), a p-GaN contact layer 196 is provided.
The p-AlGaN cladding layer 194 and the p-GaN contact layer 196 form a waveguide ridge, and an insulating film 152 having an opening 150 on the top of the waveguide ridge is formed on the surface of the p-GaN contact layer 196. Yes. A p-electrode 42 is disposed on the opening 150 and the insulating film 152, and an n-electrode 44 is disposed on the back side of the n-GaN substrate 184. A gold plating layer 46 is disposed on the surface of the p-electrode 42, and the semiconductor laser element 182 is joined to the heat sink 24 by solder via the gold plating layer 46.

In the semiconductor laser device 180, the refractive index of the n-AlGaN cladding layer 186 is higher than the refractive index of the p-AlGaN cladding layer 194.
Therefore, the effective refractive indexes of the undoped GaN guide layer 188 and the n-AlGaN cladding layer 186 disposed on the opposite side of the heat sink 24 with respect to the undoped InGaN active layer 190 are disposed on the heat sink 24 side with respect to the undoped InGaN active layer 190. Since the effective refractive index of the undoped GaN guide layer 192 and the p-AlGaN cladding layer 194 is higher than the effective refractive index, the light intensity distribution mainly expands to the n-AlGaN cladding layer 186 side disposed on the side opposite to the heat sink 24. It will be. For this reason, the vertical beam divergence angle θv is reduced, and the horizontal beam divergence angle θh is not particularly changed. Therefore, the aspect ratio, which is the ratio of the vertical beam divergence angle θv to the horizontal beam divergence angle θh, is reduced.
Further, when the vertical beam divergence angle θv is reduced, the beam diameter of the near-field image is enlarged and the light density is reduced, so that end face deterioration at high output is reduced and the reliability of the LD in high output operation is increased. .
The thermal conductivity of the p-AlGaN cladding layer 194 disposed on the heat sink 24 side is higher than the thermal conductivity of the n-AlGaN cladding layer 186 disposed on the opposite side of the heat sink 24, and the undoped The heat generated in the vicinity of the InGaN active layer 190 is easy to move to the heat sink 24 side, and the heat dissipation effect is high.

Furthermore, the light intensity distribution mainly expands to the n-AlGaN cladding layer 186 side disposed on the side opposite to the heat sink 24 with respect to the undoped InGaN active layer 190. Therefore, even if the thickness of the p-AlGaN cladding layer 194 disposed on the heat sink 24 side with respect to the undoped InGaN active layer 190 is reduced to 1.0 μm, the p-GaN contact layer 196 is optically affected. There is no. On the other hand, the n-AlGaN cladding layer 186 disposed on the side where the light intensity distribution is enlarged has a layer thickness of 2.0 μm to reduce the optical influence of the n-GaN substrate 184. Therefore, the distance from the undoped InGaN active layer 190 to the heat sink 24 can be shortened, and the heat dissipation effect can be further enhanced.
As described above, the semiconductor laser device according to this embodiment has the same effects as those of the third embodiment in the semiconductor laser device having the ridge waveguide structure.

Note that the materials, semiconductor laser structures, composition ratios and layer thicknesses of the layers described in the above embodiments are examples, and are not limited thereto.
In the above embodiment, a single quantum well structure with one active layer is shown as an example. However, the present invention is not limited to this, and the same effect can be obtained with an active layer having a multiple quantum well structure.
In the described embodiment, the broad area laser in which the current confinement structure is formed by proton injection is shown. However, the present invention is not limited to this, and the same effect can be obtained in an insulating film stripe laser having a current confinement structure by an insulating film. Play.
Further, although the ridge waveguide structure has been described as an example of the waveguide structure, the invention is not limited to this, and an embedded structure or an embedded ridge structure may be used.

  As described above, the semiconductor laser device according to the present invention is suitable for a semiconductor laser device that requires high output operation such as for solid laser excitation.

1 is a schematic diagram of a semiconductor laser device according to an embodiment of the present invention. It is a schematic diagram which shows the refractive index distribution of the semiconductor layer of the semiconductor laser apparatus concerning this invention. 1 is a perspective view of a semiconductor laser device according to an embodiment of the present invention. FIG. 4 is a cross-sectional view of the semiconductor laser device taken along the line IV-IV in FIG. 3. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention. 1 is a perspective view of a semiconductor laser device according to an embodiment of the present invention. It is sectional drawing of the semiconductor laser apparatus in the VII-VII cross section of FIG. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention. 1 is a cross-sectional view of a semiconductor laser device according to an embodiment of the present invention. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention. 1 is a cross-sectional view of a semiconductor laser device according to an embodiment of the present invention. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention. 1 is a cross-sectional view of a semiconductor laser device according to an embodiment of the present invention. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention. It is sectional drawing of the modification of the semiconductor laser apparatus which concerns on one embodiment of this invention.

Explanation of symbols

  24 heat sink, 30 n-AlGaAs cladding layer, 34 AlGaAs active layer, 38 p-AlGaAs cladding layer, 32 undoped AlGaAs guide layer, 36 undoped AlGaAs guide layer.

Claims (4)

A radiator having a main surface;
A first conductive type first electrode disposed on the main surface of the heat dissipating body and having a first main surface facing the main surface of the heat dissipating member and a second main surface facing the first main surface. A semiconductor layer;
A first main surface disposed on the second main surface of the first semiconductor layer and opposed to the second main surface of the first semiconductor layer, and a first main surface opposite to the first main surface. An active layer having two principal surfaces;
A first main surface disposed on the second main surface of the active layer and opposed to the second main surface of the active layer, and a second main surface opposite to the first main surface. A second semiconductor layer of a second conductivity type, and the first semiconductor layer and the second semiconductor layer are made of a material whose thermal conductivity increases as the refractive index decreases, The refractive index of the semiconductor layer is set smaller than the refractive index of the second semiconductor layer, and the effective refractive index between the first main surface of the active layer and the first main surface of the first semiconductor layer is The effective refractive index between the second main surface of the active layer and the second main surface of the second semiconductor layer is lower than that of the first main surface of the active layer and the first semiconductor layer. The thermal resistance between the first main surface is smaller than the thermal resistance between the second main surface of the active layer and the second main surface of the second semiconductor layer. Semiconductor laser device.   The first semiconductor layer has thermal conductivity λ1, refractive index n1 and layer thickness t1, the active layer has refractive index na, and the second semiconductor layer has thermal conductivity λ2, refractive index n2 and layer thickness. 2. The semiconductor laser device according to claim 1, wherein t> 2 and na> n2, na> n1, and t2 / λ2> t1 / λ1.   A first guide layer having a refractive index n3, a thermal conductivity λ3, and a layer thickness t3 is provided between the first semiconductor layer and the active layer, and a refractive index n4 is provided between the second semiconductor layer and the active layer. And a second guide layer having a thermal conductivity λ4 and a layer thickness t4 is further provided, wherein na> n3, na> n4, and t4 / λ4> t3 / λ3. 1. The semiconductor laser device according to 1. A radiator having a main surface;
A first semiconductor layer of a first conductivity type disposed on the main surface of the radiator,
One or more first guide layers disposed on the first semiconductor layer;
An active layer disposed on the first guide layer;
One or more second guide layers disposed on the active layer;
A second semiconductor layer of a second conductivity type disposed on the second guide layer,
The first semiconductor layer and the second semiconductor layer are made of a material whose thermal conductivity increases as the refractive index decreases, and the thermal resistance determined from the first semiconductor layer and the first guide layer is the second. The effective refractive index determined by the second guide layer and the second semiconductor layer is smaller than the thermal resistance determined by the guide layer and the second semiconductor layer, and the effective refractive index determined by the first semiconductor layer and the first guide layer is determined by the second guide layer and the second semiconductor layer. A semiconductor laser device having a refractive index lower than that of the semiconductor laser device.

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