JP2004336085A - Semiconductor laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser which can produce a laser beam having a nearly round shape as well as having a high power output. <P>SOLUTION: An n-GaAs layer 2 is formed on an n-GaAs substrate 1, and further on the layer 2, an n-Al<SB>0.4</SB>Ga<SB>0.6</SB>As clad layer 3, an n-Al<SB>0.2</SB>Ga<SB>0.8</SB>As light guide layer 4, a multiple quantum well structure active layer 5 made of an Al<SB>0.2</SB>Ga<SB>0.8</SB>As/GaAs, a p-Al<SB>0.4</SB>Ga<SB>0.6</SB>As cladding layer 7, and a p-GaAs layer 8 are laminated in a mesa structure. A total thickness of the active layer 5 and the light guide layer 4 is set above 1.5μm. An insulating film 9 and a p-type electrode 10 are formed on the n-GaAs layer 2 and on the top surface of the mesa portion. A stripe is formed as wide as 400μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor laser, and is particularly suitable as a semiconductor laser for distance measurement that constitutes a robot eye, a laser radar system, or the like.

  In recent years, systems that measure the distance between automobiles using a semiconductor laser and maintain a constant inter-vehicle distance, or issue an alarm or apply a brake when approaching a car ahead ahead too much have been studied. I have. In such a system, it is necessary to detect an object at a distance of 100 m, and a semiconductor laser is required to emit light of several tens of watts by pulse driving. FIG. 8 shows the structure of this high-power semiconductor laser. An n-GaAs layer 22 and an n-AlGaAs cladding layer 23 are stacked on an n-GaAs substrate 21, and an active layer 24, a p-AlGaAs cladding layer 25, and a p-GaAs layer 26 are stacked on the n-GaAs layer 22 in a mesa shape. . Here, the active layer is a layer that converts injected light into light by confining and recombining the injected carriers. Further, an insulating film 27 and a p-type electrode 28 are formed. On the other hand, an n-type electrode 29 and an Au / Sn layer 30 are formed on the back surface of the n-GaAs substrate 21.

  In general, a large output pulse semiconductor laser of several tens of W class needs to have a stripe width of at least 100 μm or more as shown in FIG. On the other hand, the thickness of the active layer 24 needs to be about 0.1 μm for the purpose of confining carriers in a narrow region and reducing the threshold current. As described above, in the high-power pulsed semiconductor laser, the stripe width is larger than the wavelength and the thickness of the active layer is smaller, so that light is not diffracted in the spreading direction (horizontal direction) of the active layer, and Since diffraction occurs in the thickness direction (vertical direction) of the layer, the beam shape is an elliptical shape spread in the thickness direction (vertical direction) of the active layer, and the elliptic ratio (the major axis of the beam cross section in FIG. 9) The ratio (H / W of H to the minor axis W) is about 2.5 to 3.2.

  An optical lens is used to focus the laser beam in a range having a desired divergence angle. From the viewpoint of easy lens design and system miniaturization, the beam shape of the emitted laser beam is used. Is preferably as close as possible to a circle, and an elliptic ratio smaller than “2.5” is required.

As a general method for obtaining a laser beam having a beam shape close to a circle, Patent Document 1 discloses a small-output semiconductor laser in which a semiconductor has a lens portion having a high refractive index. However, there is a problem that a new process is required to form a lens portion in a semiconductor. Therefore, Japanese Patent Application Laid-Open No. H11-157,086 discloses a technique for obtaining a laser beam having a circular shape without the need for a lens unit. In Patent Document 2, in a low power semiconductor laser, optical guide layers (confinement layers) having a lower refractive index than the active layer are formed above and below the active layer, and the width of the active layer is set to 0.5 μm or more and 1.5 μm or more. It is as follows. Here, the light guide layer is a layer that functions to confine and guide light generated in the active layer.
JP-A-55-143092 JP-A-4-158787 JP-A-61-79288

  However, the semiconductor laser disclosed in Patent Literature 2 obtains a laser beam having a nearly circular beam shape by using a semiconductor laser of a small output (several tens mW) class (stripe width; several μm to several tens μm). However, when used in a high-power pulsed semiconductor laser having a stripe width of 100 μm or more, simply limiting the width of the active layer and forming a structure sandwiched between light guide layers can produce a laser beam having a nearly circular beam shape. It turns out I can't get it.

  This is because, in general, in the case of a semiconductor laser having a small output (stripe width is less than 100 μm), the emission start current (threshold current) changes, so that the thickness of the light guide layer cannot be made too large. Therefore, it is thought that the only way to change the beam shape is to change the stripe width, change the width of the active layer, or add a carrier barrier layer on both sides of the active layer (Patent Document 3). It is because. Since it is considered that this emission start current change occurs even in a semiconductor laser having a stripe width of 100 μm or more, a high-power semiconductor laser can obtain only an elliptic ratio of about 2.5 to 3.2 as described above. I didn't.

  Accordingly, an object of the present invention is to provide a semiconductor laser capable of obtaining a laser beam having a nearly circular beam shape in a high-output semiconductor laser having a stripe width of 100 μm or more.

  The present inventors have found that the light confinement effect is determined by the total thickness of the light guide layer and the active layer.

Therefore, the invention according to claim 1 is a semiconductor laser having a stripe width of 100 μm or more,
Electrons and holes as carriers are injected, an active layer that generates light by recombining the injected carriers, and an active layer formed at least on a side of the active layer that injects the electrons, A light guide layer formed of a material having a refractive index substantially lower than that of the light guide layer and confining the light generated in the active layer; and the light guide layer formed above and below the active layer including the light guide layer. Having a cladding layer substantially composed of a material having a lower refractive index,
The total thickness of the active layer and the light guide layer is 1.5 μm or more, and
A gist of the present invention is a semiconductor laser in which the distance of the electrons and holes from the cladding layer to the active layer is shorter in the holes than in the electrons.

  According to a second aspect of the present invention, there is provided a semiconductor laser according to the first aspect, wherein the thickness of the active layer is set to 0.05 μm or more and 0.15 μm or less.

  According to a third aspect of the present invention, there is provided a semiconductor laser according to the first or second aspect, wherein the active layer, the light guide layer, and the cladding layer are made of an AlGaAs-based material.

  According to a fourth aspect of the present invention, the active layer, the light guide layer, and the clad layer according to any one of the first to third aspects are formed of an InGaAlP-based material, an InGaAsP-based material, and an InGaAsSb-based material. The gist of the present invention is a semiconductor laser made of any one of AlGaInN-based materials.

  According to a fifth aspect of the present invention, there is provided a semiconductor laser according to any one of the first to fourth aspects, wherein the total thickness of the active layer and the light guide layer is 5.5 μm or less. And

  According to a sixth aspect of the present invention, an n-type cladding layer is disposed on one surface of the active layer according to any one of the first to fifth aspects with an n-type light guide layer interposed therebetween. A gist of the present invention is a semiconductor laser in which a p-type cladding layer is directly disposed on the other surface of the active layer.

  According to a seventh aspect of the present invention, in the first aspect of the present invention, the cladding layer includes a first conductivity type first cladding layer formed on one surface of the active layer. A second cladding layer of a second conductivity type formed on the other surface of the active layer, a semiconductor substrate formed on the first cladding layer side, and a first cladding layer of the semiconductor substrate. The gist of the present invention is a semiconductor laser having a lower surface electrode formed on the side opposite to the above-mentioned cladding layer and an upper surface electrode formed on the second cladding layer and having a stripe width of 100 μm or more.

  The invention according to claim 8, wherein an N-type semiconductor substrate having a lower surface electrode on a lower surface, an N-type first cladding layer formed on an upper surface of the semiconductor substrate opposite to the lower surface electrode, An N-type light guide layer formed on the first clad layer and having a refractive index substantially higher than that of the first clad layer and made of an AlGaAs-based material; and an AlGaAs-based material formed on the light guide layer. Consisting of an active layer having a refractive index substantially higher than that of the light guide layer, generating light by injecting carriers and recombining the injected carriers, and formed on the active layer; A first P-type second cladding layer having a refractive index substantially lower than that of the light guide layer, and an upper surface electrode formed on the second cladding layer and having a stripe width of 100 μm or more; Light guide layer and the active layer Serial second light guide layer and the total thickness of 1.5μm or more, and a semiconductor laser which was 5.5μm or less and its gist.

  According to the first to eighth aspects of the present invention, as the thickness of the light guide layer increases, the diffraction effect of light in the thickness direction (vertical direction) of the light guide layer decreases, and the beam becomes narrower. On the other hand, the diffraction effect in the spreading direction (horizontal direction) of the light guide layer does not change. As shown in FIG. 4, when the total thickness of the active layer and the light guide layer is 1.5 μm or more, the beam approaches a circular shape.

  Furthermore, the distance that electrons and holes injected from the cladding layer reach the active layer is shorter in the holes than in the electrons, so that the overall resistance is reduced, the heat generation of the element is suppressed, and the reliability is reduced. Is improved. In the invention according to claims 6 and 8, an n-type cladding layer is arranged on one surface of the active layer via an n-type light guide layer, and a p-type cladding layer is provided on the other surface of the active layer. Directly arranged, electrons as carriers are injected from the n-type cladding layer into the active layer via the n-type light guide layer, while holes as carriers are directly injected from the p-type cladding layer into the active layer. Injected.

  When the thickness of the active layer is 0.05 μm or more and 0.15 μm or less as in the second aspect of the invention, carriers are confined only in a narrow region of the active layer, so that the threshold current increases, The output does not decrease.

  When the active layer, the light guide layer, and the cladding layer are made of an AlGaAs-based material, the ellipticity of the beam becomes smaller than “2.5”.

  If the active layer, the light guide layer, and the cladding layer are made of any one of InGaAlP-based materials, InGaAsP-based materials, InGaAsSb-based materials, and AlGaInN-based materials as in the invention according to claim 4, the beam intensity can be improved. The elliptical ratio becomes smaller than “2.5”.

  When the total thickness of the active layer and the light guide layer is further set to 5.5 μm or less, the beam approaches a circular shape.

(1st Embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 2 is a perspective view of the high-power semiconductor laser according to the present embodiment, and FIG. 1 is a cross-sectional view of the high-power semiconductor laser. FIG. 3 shows an energy band diagram of the high-power semiconductor laser. This high power semiconductor laser is pulse-driven.

On an n-GaAs substrate 1 as a semiconductor substrate, an n-GaAs layer 2, an n-Al _0.4 Ga _0.6 As clad layer 3 as a first clad layer, and n-Al _0.2 Ga _0.8 as a first optical guide layer. As light guide layer 4, active layer 5 having an Al _0.2 Ga _0.8 As / GaAs multiple quantum well structure, p-Al _0.2 Ga _0.8 As light guide layer 6 as a second light guide layer, and second clad layer as a second clad layer A p-Al _0.4 Ga _0.6 As clad layer 7 and a p-GaAs layer 8 are sequentially stacked. The active layer 5, and Al _0.2 Ga _0.8 As and GaAs are stacked alternately, Al _0.2 Ga _0.8 As is five layers are formed GaAs is six layers. The clad layer 3, the light guide layer 4, the active layer 5, the light guide layer 6, the clad layer 7, and the GaAs layer 8 have a mesa shape. The front end face (the front end face in FIG. 2) of the active layer 5 is coated with a low reflection film, and the rear end face is coated with a high reflection film.

The thickness of the n-GaAs layer 2 is 500 nm (0.5 μm), the thickness of the n-Al _0.4 Ga _0.6 As cladding layer 3 is 1 μm, and the thickness of the n-Al _0.2 Ga _0.8 As optical guide layer 4 is 0 to 2 .25 μm. Further, in the active layer 5, even in the thickness of the Al _0.2 Ga _0.8 As it is the 7.5nm (0.0075μm), and the sum of Al _0.2 Ga _0.8 because As there are five layers, Al _0.2 Ga _0.8 As Has a thickness of 37.5 nm (= 7.5 nm × 5 layers). Further, the thickness of one layer of GaAs in the active layer 5 is 15 nm (0.015 μm), and the total thickness of GaAs is 90 nm (= 15 nm × 6 layers) because there are six layers of GaAs. Therefore, the thickness of the active layer 5 is 127.5 nm, that is, 0.1275 μm.

The thickness of the p-Al _0.2 Ga _0.8 As light guide layer 6 is 0 to 2.25 μm, the thickness of the p-Al _0.4 Ga _0.6 As cladding layer 7 is 1 μm, and the thickness of the p-GaAs layer 8 is 0.8 μm. is there.

  In the present embodiment, the thickness of the active layer 5 is 127.5 nm, and the total thickness of the active layer 5, the light guide layer 4, and the light guide layer 6 is 1.5 μm or more.

The refractive index (average refractive index) of the active layer 5 is “3.6”, and the refractive indexes of the n-Al _0.2 Ga _0.8 As light guide layer 4 and the p-Al _0.2 Ga _0.8 As light guide layer 6 are respectively The refractive index of the n-Al _0.4 Ga _0.6 As cladding layer 3 and the refractive index of the p-Al _0.4 Ga _0.6 As cladding layer 7 are “3.3”, respectively. Then, as shown in FIG. 3, the light guide layers 4 and 6 are set to have a band gap larger than that of the active layer 5.

An insulating film 9 made of SiO ₂ is formed on the upper surface of the n-GaAs layer 2 and the mesa-shaped portion, and a window 13 without the insulating film 9 is formed on the upper surface of the mesa-shaped portion. Furthermore, a p-type electrode 10 as a top electrode made of Cr / Au is formed thereon, and has an ohmic contact with the p-GaAs layer 8. The width of the window 13, that is, the stripe width is 400 μm.

  On the back surface of the n-GaAs substrate 1, an n-type electrode 11 as a lower surface electrode made of AuGe / Ni / Au is formed, and is in ohmic contact with the n-GaAs substrate 1. An Au / Sn layer 12 is formed on the surface of the n-type electrode 11, and the Au / Sn layer 12 is a bonding agent for bonding the semiconductor laser element and a heat sink made of Cu as a pedestal.

  As shown in FIG. 2, the vertical and horizontal dimensions of this high-power semiconductor laser are 500 μm × 600 μm.

  Next, a method for manufacturing this high-power semiconductor laser will be described.

First, the n-GaAs substrate 1 n-GaAs layer 2 on, n-Al _0.4 Ga _0.6 As cladding layer _{3, n-Al 0.2 Ga 0.8} As optical guide layer _{4, Al 0.2 Ga 0.8 As /} GaAs multiple quantum well structure The active layer 5, the p-Al _0.2 Ga _0.8 As optical guide layer 6, the p-Al _0.4 Ga _0.6 As clad layer 7, and the p-GaAs layer 8 are sequentially laminated by MOCVD (Metal Organic Chemical Vapor Deposition). Thereafter, a mesa-shaped portion is formed by etching.

Subsequently, an insulating film 9 made of SiO ₂ is formed on the upper surface of the n-GaAs layer 2 and the mesa-shaped portion by a plasma CVD method, and a window 13 is formed by opening a window by etching. Then, a p-type electrode 10 made of Cr / Au is formed on the insulating film 9 by an electron beam evaporation method, and a heat treatment is performed at about 360 ° C. to make an ohmic contact.

  Further, an n-type electrode 11 made of AuGe / Ni / Au is formed on the back surface of the n-GaAs substrate 1 by an electron beam evaporation method, and heat treatment is performed to make ohmic contact. After that, the Au / Sn layer 12 is formed by an electron beam evaporation method. Finally, the end face is cleaved to obtain a semiconductor laser chip.

By passing a pulse current between the p-type electrode 10 and the n-type electrode 11 of this laser, holes are generated from the p-Al _0.4 Ga _0.6 As clad layer 7 side to the n-Al _0.4 Ga _0.6 As clad layer 3 side. More electrons are injected into the active layer 5 and recombine to emit light. The light emitted in this manner is amplified by repeating reflection on the end faces before and after the cleavage, and is amplified and laser oscillates, and laser light is emitted from the front end face.

FIG. 4 shows that the thickness of the active layer 5 is 127.5 nm, and the thickness of the n-Al _0.2 Ga _0.8 As light guide layer 4 and the thickness of the p-Al _0.2 Ga _0.8 As light guide layer 6 are changed. 10 shows the measurement results of the ellipticity ratio of the beam (H / W in FIG. 9) when the total thickness of the light guide layer 5, the light guide layer 4 and the light guide layer 6 is changed. Here, the thickness of the light guide layer 4 and the thickness of the light guide layer 6 were made equal.

  The following can be seen from FIG. That is, by setting the total thickness of the active layer 5, the light guide layer 4, and the light guide layer 6 to 1.5 μm or more, the elliptic ratio of the beam can be made smaller than “2.5”. Furthermore, if the total thickness of the active layer 5, the light guide layer 4 and the light guide layer 6 is selected to be about 4.5 μm, a beam having an elliptic ratio of “1”, that is, a nearly circular beam can be obtained. This is because, as the thickness of the light guide layer increases, the light diffraction effect decreases in the thickness direction (vertical direction) of the light guide layer and the beam narrows, whereas the light guide layer expands. This is because the (horizontal) diffraction effect does not change. As a result, as shown in FIG. 4, the ellipticity of the beam can be controlled from about "1" to about "3". By setting the total thickness of the active layer 5, the light guide layer 4 and the light guide layer 6 to 5.5 μm or less, the ellipticity of the beam can be made larger than 0.4. This is nothing but a change in the aspect ratio of the ellipse ratio of 2.5.

  In FIG. 4, the hatched area indicates the elliptic ratio of the high-power semiconductor laser (semiconductor laser without a light guide layer) shown in FIG. 8, and the elliptic ratio is about 2.5 to 3.2. is there.

  Here, by setting the thickness of the active layer 5 to around 0.1 μm (between 0.1 ± 0.05 μm), the carriers can be confined in a narrow place and the carriers can be effectively recombined. The threshold current can be reduced, and the light output can be prevented from lowering.

  As described above, in order to make the total thickness of the active layer 5, the light guide layer 4 and the light guide layer 6 1.5 μm or more, and to make the thickness of the active layer 5 near 0.1 μm, the present embodiment In this example, the total thickness of the light guide layer 4 and the light guide layer 6 is set to 1.5 μm or more.

In the measurement shown in FIG. 4, the thickness of the n-Al _0.2 Ga _0.8 As light guide layer 4 and the thickness of the p-Al _0.2 Ga _0.8 As light guide layer 6 are the same as described above, but may be different. As will be described in detail in a second embodiment described later, if holes and electrons as carriers are shorter than electrons at a distance from the cladding layer to the active layer, the overall resistance decreases, and the device Is suppressed and the reliability is improved.

  As described above, the semiconductor laser according to the present embodiment has a stripe width of 400 μm for large output, and has the light guide layers 4 and 6 having a lower refractive index than the active layer 5 above and below the active layer 5. It has cladding layers 3 and 7 having a lower refractive index than the light guide layers 4 and 6 above and below the active layer 5 including the guide layers 4 and 6, and the total thickness of the active layer 5 and the light guide layers 4 and 6. Was set to 1.5 μm or more. Therefore, as the thickness of the light guide layers 4 and 6 increases, the diffraction effect of light in the thickness direction (vertical direction) of the light guide layers 4 and 6 decreases and the beam narrows. On the other hand, the diffraction effect of the light guide layers 4 and 6 in the spreading direction (horizontal direction) does not change. In this way, by making the total thickness of the active layer 5 and the light guide layers 4 and 6 1.5 μm or more, the beam can be made close to a circle.

  Also, since the thickness of the active layer 5 is set to 0.1275 μm, which is in the range of 0.05 to 0.15 μm, carriers are confined only in a narrow region of the active layer 5, thereby reducing the threshold current. An increase and a decrease in light output can be prevented.

  Further, the active layer 5, the light guide layers 4 and 6, and the clad layers 3 and 7 were made of an AlGaAs-based material. Therefore, by setting the total thickness of the active layer 5 and the light guide layers 4 and 6 to 1.5 μm or more, the elliptical ratio of the beam can be made smaller than “2.5”. As described above, it is possible to obtain a nearly circular beam shape in which the elliptic ratio of the beam is smaller than “2.5” while maintaining a large output, and it becomes easy to design and manufacture a lens for condensing light. It is possible to manufacture a laser having a beam shape that meets the requirements of the above.

  Furthermore, by using an AlGaAs-based material, a laser having an oscillation wavelength of 0.8 μm can be obtained.

  As described above, in general, in a semiconductor laser having a small output (a stripe width of less than 100 μm), the thickness of the light guide layer cannot be made too large due to the problem that the emission start current (threshold current) changes. However, it was thought that the only way to change the beam shape was to change the stripe width, change the width of the active layer, and add a carrier barrier layer on both sides of the active layer (Patent Document 3). . Since it is considered that this emission start current change occurs even in a semiconductor laser having a stripe width of 100 μm or more, a high-power semiconductor laser can obtain only an elliptic ratio of about 2.5 to 3.2 as described above. I didn't. However, the present inventors have found that in a semiconductor laser having a stripe width of 100 μm or more, even if the thickness of the light guide layer is changed, the threshold current (light emission start current) hardly changes. It has been found that the shape of the beam can be controlled by positively changing the thickness of the guide layer and the thickness of the active layer. Then, they have found that the beam shape can be made smaller than “2.5” by making the total thickness of the light guide layer and the active layer 1.5 μm or more.

(2nd Embodiment)
Next, a second embodiment of the present invention will be described focusing on differences from the first embodiment.

In the high-power semiconductor laser of this embodiment, as shown in FIGS. 5 and 6, the n-Al _0.2 Ga _0.8 As light guide layer 4 is provided only under the active layer 5, and the light guide layer is formed on the active layer 5. Not provided. As a result, electrons as carriers are injected from the n-Al _0.4 Ga _0.6 As cladding layer 3 into the active layer 5 via the n-Al _0.2 Ga _0.8 As light guiding layer 4, and holes as carriers are p-type. The active layer 5 is directly injected from the Al _0.4 Ga _0.6 As clad layer 7. Therefore, the distance that electrons and holes as carriers reach the active layer 5 is shorter for holes than for electrons. Therefore, the overall resistance is reduced, the heat generation of the element is suppressed, and the reliability is improved. Also in this case, by setting the total film thickness of the active layer 5 and the n-Al _0.2 Ga _0.8 As light guide layer 4 to 1.5 μm or more, the elliptic ratio becomes higher than “2.5” as in the first embodiment. A smaller beam shape can be obtained.

  The present invention is not limited to the above embodiments. For example, in the above embodiments, the stripe width is 400 μm, but the present invention can be applied to any semiconductor laser having a stripe width of 100 μm or more. Further, in addition to the pulse-driven semiconductor laser, it may be used for a DC-driven (CW) semiconductor laser. Furthermore, in each of the above embodiments, the active layer, the light guide layer, and the cladding layer are made of an AlGaAs-based material, but may be made of other materials such as InGaAlP, InGaAsP, InGaAsSb, and AlGaInN. . In this case, by setting the total thickness of the active layer 5 and the light guide layer to be 2.5 μm or more and 5.5 μm or less, the ellipticity of the beam can be set to substantially “2” or less. Then, a laser having an oscillation wavelength according to the material can be obtained.

  Further, in each of the above embodiments, the description has been made using the mesa type semiconductor laser. However, as shown in FIG. 7, the semiconductor laser may be a non-mesa type semiconductor laser.

FIG. 2 is a cross-sectional view of the high-power semiconductor laser according to the first embodiment. FIG. 2 is a perspective view of the high-power semiconductor laser according to the first embodiment. FIG. 2 is an energy band diagram of the high-power semiconductor laser according to the first embodiment. 9 is a graph showing the relationship between the total thickness of the active layer and the light guide layer and the elliptic ratio. FIG. 6 is a cross-sectional view of a high-power semiconductor laser according to a second embodiment. FIG. 9 is an energy band diagram of the high-power semiconductor laser according to the second embodiment. FIG. 10 is a perspective view of a high-power semiconductor laser according to another embodiment. FIG. 9 is a perspective view of a conventional high-power semiconductor laser. Sectional drawing which shows the cross section of a beam.

Explanation of reference numerals

Reference Signs List 1 n-GaAs substrate as semiconductor substrate 3 n-Al _0.4 Ga _0.6 As clad layer as first clad layer 4 n-Al _0.2 Ga _0.8 As light guide layer as first light guide layer 5 active layer 6 2 p-Al _0.2 Ga _0.8 As light guide layer as light guide layer 7 p-Al _0.4 Ga _0.6 As clad layer as second clad layer 10 p-type electrode as upper surface electrode 11 n-type electrode as lower surface electrode

Claims (8)

A semiconductor laser having a stripe width of 100 μm or more,
Electrons and holes as carriers are injected, an active layer that generates light by recombining the injected carriers,
A light guide layer formed at least on the side where the electrons are injected with respect to the active layer and made of a material having a refractive index substantially lower than that of the active layer and confining the light generated in the active layer;
A cladding layer formed above and below the active layer including the light guide layer, and made of a material having a substantially lower refractive index than the light guide layer;
The total thickness of the active layer and the light guide layer is 1.5 μm or more, and
A semiconductor laser, wherein a distance of the electrons and holes from the cladding layer to the active layer is shorter in the holes than in the electrons. 2. The semiconductor laser according to claim 1, wherein the thickness of the active layer is 0.05 μm or more and 0.15 μm or less. 3. The semiconductor laser according to claim 1, wherein the active layer, the light guide layer, and the clad layer are made of an AlGaAs-based material. 4. The method according to claim 1, wherein the active layer, the light guide layer, and the cladding layer are made of any one of an InGaAlP-based material, an InGaAsP-based material, an InGaAsSb-based material, and an AlGaInN-based material. The semiconductor laser according to claim 1. The semiconductor laser according to claim 1, wherein a total thickness of the active layer and the light guide layer is set to 5.5 μm or less. An n-type cladding layer is disposed on one surface of the active layer via an n-type light guide layer, and a p-type cladding layer is directly disposed on the other surface of the active layer. Item 6. The semiconductor laser according to any one of items 1 to 5. The cladding layer includes a first conductivity type first cladding layer formed on one surface of the active layer and a second conductivity type second cladding layer formed on the other surface of the active layer. Become
Further, a semiconductor substrate formed on the first clad layer side, a lower surface electrode formed on a side of the semiconductor substrate opposite to the first clad layer, and a semiconductor substrate formed on the second clad layer having a thickness of 100 μm The semiconductor laser according to any one of claims 1 to 5, further comprising an upper electrode having the above stripe width. An n-type semiconductor substrate having a lower surface electrode on the lower surface;
An n-type first cladding layer formed on the upper surface of the semiconductor substrate opposite to the lower surface electrode;
An n-type light guide layer formed on the first clad layer and having a refractive index substantially higher than that of the first clad layer and made of an AlGaAs-based material;
An active layer formed on the light guide layer, made of an AlGaAs-based material, having a refractive index substantially higher than that of the light guide layer, injecting carriers and recombining the injected carriers to generate light. Layers and
A p-type second cladding layer formed directly on the active layer and having a substantially lower refractive index than the light guide layer;
An upper surface electrode formed on the second cladding layer and having a stripe width of 100 μm or more;
A semiconductor laser, wherein the total thickness of the first light guide layer, the active layer, and the second light guide layer is 1.5 μm or more and 5.5 μm or less.

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