JPH098414A - Semiconductor laser device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser device having a small astigmatic difference, low noise and the stabilized lateral mode from the low output to the high output. SOLUTION: On an N-type GaAs semiconductor board 1, an N-type GaAs buffer layer 2, an N-type Ga0.45 Al0.55 As first clad layer 3, a Ga0.85 Al0.15 As active layer 4, a P-type Ga0.45 Al0.55 As first light guiding layer 5, and a P-type Ga0.8 Al0.2 As second light guiding layer 6 are formed. On the second light guiding layer 6, a P-type Ga0.45 Al0.55 As stripe region 7a is formed, and an N-type Ga0.3 Al0.7 As current blocking layer 7 is formed on both sides of the stripe region 7a. A P-type Ga0.45 Al0.55 As second clad layer 8 is formed on the stripe region 7a and the current blocking layer 7, and a P-type GaAs contact layer 9 is formed on the second clad layer 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device suitable as a light source for an optical disk or the like, which oscillates in a fundamental transverse mode with a small astigmatic difference, low noise, and stable from low output to high output.

[0002]

2. Description of the Related Art A conventional semiconductor laser device will be described below.

FIG. 15 is a sectional view of a conventional semiconductor laser device disclosed in Japanese Patent Laid-Open No. 6-196801. As shown in FIG. 15, the conventional semiconductor laser device is
An n-type G is formed on a semiconductor substrate 21 made of n-type GaAs.
The buffer layer 22 made of aAs is formed, the first cladding layer 23 made of n-type Ga _0.5 Al _0.5 As is formed on the buffer layer 22, and the G layer is formed on the first cladding layer 23.
The active layer 24 made of a _0.85 Al _0.15 As is formed, the first optical guide layer 25 made of p-type Ga _0.5 Al _0.5 As is formed on the active layer 24, and the active layer 24 made of p 0.8 is formed on the first optical guide layer 25. The second optical guide layer 26 made of Ga _0.8 Al _0.2 As is formed. In addition, on the second optical guide layer 26, p-type Ga _0.5 Al _0.5 As that serves as a current channel is formed.
Stripe regions 27a made of n-type Ga _0.4 Al _0.6 As are formed in regions other than the stripe regions 27a on the second optical guide layer 26. A protective layer 28 made of Ga _0.8 Al _0.2 As is formed on the current blocking layer 27, and p is formed on the protective layer 28 and the stripe region 27a.
Type second cladding layer 29 made of Ga _0.5 Al _0.5 As
Is formed, and p-type GaA is formed on the second cladding layer 29.
A contact layer 30 made of s is formed.

In this case, in order to obtain stable single transverse mode oscillation, the AlAs mixed crystal ratio of the current block layer 27 is set higher than the AlAs mixed crystal ratio of the second cladding layer 29.

In the semiconductor laser device of this structure,
The current injected from the contact layer 30 is confined in the stripe region 27a, and a single transverse mode laser beam having a wavelength of 780 nm band oscillates in the active layer 24 below the stripe region 27a. According to this structure, the current blocking layer 27 is transparent to the laser light, and the light largely exudes to the outside of the stripe region 27a, so that the saturable absorption region can be easily formed, and thus self-sustained pulsation can be easily obtained. A semiconductor laser device that is easy and has low noise can be obtained.

[0006]

However, in the above-mentioned conventional semiconductor laser device, when the spectrum is made into multiple modes so as to obtain a low noise characteristic sufficient to be applied as a light source of an optical disk, that is, self-pulsation occurs. In this case, the light distribution is expanded in the horizontal direction, and the active layer 24 below the current block layer 27 is used as the saturable absorption region. For this purpose, it is necessary to make the difference in refractive index between the inside and outside of the stripe region 27a considerably small.

However, since the refractive index in the stripe region decreases due to the plasma effect during laser oscillation, the effective refractive index difference between the inside and outside of the stripe region is 6 × 10 in order to obtain a stable transverse mode even at high output. ^-3 or more is required. On the other hand, in order to obtain self-pulsation in the conventional structure, the effective refractive index difference is 6 × 10.
Must be less than ^-3 . Therefore, the conventional structure has a problem that the transverse mode is deformed at high output.

In addition, the saturable absorption region in the active layer 24 below the current blocking layer 27 causes a bend in the wavefront propagating in the waveguide, resulting in an astigmatic difference when the laser beam is focused by a lens. was there.

The deformation of the transverse mode and the presence of the astigmatic difference when the laser beam is focused cause serious problems because the spot cannot be narrowed down in the application to the optical disk.

To solve this problem, JP-A-61-1
74685 or JP-A-61-171188,
A method has been proposed in which only the end face of the resonator has a refractive index guide structure.

However, in the internal region of the resonator, the effective refractive index difference is made small for self-sustained pulsation, so that a stable transverse mode cannot be maintained at high output.

For the above reasons, according to the conventional structure,
It has not been possible to realize a low-noise, high-output semiconductor laser device having a stable transverse mode and no astigmatic difference.

The present invention solves the above problems and provides a high output semiconductor laser device having low noise characteristics, stable transverse mode even at high output, and no astigmatic difference. The purpose is to

[0014]

In order to achieve the above object, the present invention provides a semiconductor laser device in which a stripe region is discontinuous and a current non-injection portion is provided in the stripe region. A saturable absorption region is formed on the side.

According to a first aspect of the present invention, there is provided a solving means, in which an active layer made of a semiconductor layer and a first active layer formed on the active layer are provided.
A light guide layer made of a conductive semiconductor layer, a stripe region made of a first conductivity type semiconductor layer formed on the light guide layer, and formed on both sides of the stripe region on the light guide layer. On the premise of a semiconductor laser device including a second conductivity type current blocking layer, the stripe region has at least one discontinuous portion with respect to the cavity direction. .

With the above structure, the current injection into the active layer is determined by the stripe region, but no current is injected below the discontinuous portion of the stripe region in the active layer. Therefore, the saturable absorption region can be formed below the discontinuous portion of the stripe region in the active layer.

The solution means taken by the invention of claim 2 is Ga
_An active layer made of a _1-X Al _X As layer, a light guide layer made of a Ga _{1 -Y 1} Al _{Y 1} As layer of the first conductivity type formed on the active layer, and formed on the light guide layer Area of the first conductivity type Ga _{1 -Y 2} Al _{Y 2} As layer and a second conductivity type Ga _{1 -Z} Al _Z As layer formed on both sides of the stripe area on the light guide layer. A semiconductor laser device including a current blocking layer made of: is used, and Z is present between X, Y1, Y2, and Z of respective mixed crystal ratios of the active layer, the light guide layer, the stripe region, and the current blocking layer.
The relations of>Y2> X ≧ 0 and Y1> X are established, and the stripe region has at least one discontinuous portion in the resonator direction.

With the above structure, the Al in the stripe region is
Since the AlAs mixed crystal ratio of the current block layer is higher than the As mixed crystal ratio, the effective refractive index of the stripe region becomes higher than the effective refractive index outside the stripe region, and the stable single lateral by the refractive index guiding mechanism is obtained. Mode oscillation can be obtained.

According to a third aspect of the present invention, there is provided a light guide comprising an active layer having a quantum well structure and a Ga _{1 -Y 1} Al _{Y 1} As layer of the first conductivity type formed on the active layer. Layer and Ga of the first conductivity type formed on the light guide layer
_A stripe region made of a _1-Y2 Al _Y2 As layer; and a current blocking layer made of Ga _{1 -Z} Al _Z As of the second conductivity type formed on both sides of the stripe region on the light guide layer. Assuming a semiconductor laser device, Y1> 0 and Z>Y2> 0 between Y1, Y2 and Z of respective mixed crystal ratios of the light guide layer, the stripe region and the current block layer.
And the stripe region has at least one discontinuous portion with respect to the cavity direction.

With the above structure, in the semiconductor laser device in which the active layer has a quantum well structure, the AlAs mixed crystal ratio of the current block layer is higher than the AlAs mixed crystal ratio of the stripe region, so that the effective refractive index of the stripe region is higher. Becomes higher than the effective refractive index outside the stripe region, and stable single transverse mode oscillation can be obtained by the refractive index guiding mechanism.

[0021] The solution means taken by the invention of claim 4 is Ga
Active layer composed of _1-x Al _x As layer, first optical guide layer composed of Ga _{1 -Y 1} Al _{Y 1} As layer of first conductivity type formed on the active layer, and first optical guide layer A second light guide layer made of Ga _{1 -Y 2} Al _Y2 As of the first conductivity type formed on the first light guide layer, and a first conductivity type G formed on the second light guide layer.
a _1-Y3 Al _Y3 As layer stripe region, and a current blocking layer formed of a second conductivity type Ga _1-Z Al _Z As layer formed on both sides of the stripe region on the second optical guide layer. On the premise of a semiconductor laser device including the following, the active layer, the first light guide layer, the second light guide layer, the stripe region, and the current block layer have a mixed crystal ratio of X and Y.
The relationship of Z>Y3>Y2> X ≧ 0 and Y1> Y2 is established between 1, Y2, Y3 and Z, and the stripe region has at least one discontinuous portion in the cavity direction. The configuration is as follows.

With the above structure, Al of the second light guide layer is formed.
Since the As mixed crystal ratio is lower than the AlAs mixed crystal ratio of the first optical guide layer, the interface resistance between the second optical guide layer and the stripe region can be easily reduced.

Further, since the second light guide layer is transparent to the laser light oscillated by the active layer, heat generation in the vicinity of the active layer is suppressed.

According to a fifth aspect of the present invention, there is provided a first solution comprising an active layer having a quantum well structure and a Ga _{1 -Y 1} Al _{Y 1} As layer of the first conductivity type formed on the active layer. An optical guide layer, a second optical guide layer formed of a Ga _{1 -Y 2} Al _{Y 2} As layer of the first conductivity type formed on the first optical guide layer, and formed on the second optical guide layer. First conductivity type Ga _{1- Y3}
A semiconductor having a stripe region made of an Al _Y3 As layer and a current blocking layer made of Ga _{1 -Z} Al _Z As of the second conductivity type formed on both sides of the stripe region on the second light guide layer. Assuming a laser device, Z>Y3>Y2> between Y1, Y2, Y3 and Z of the respective mixed crystal ratios of the active layer, the first light guide layer, the second light guide layer, the stripe region and the current block layer. The relationship of 0 and Y1> Y2 is established, and the stripe region has at least one discontinuous portion in the resonator direction.

With the above structure, in the semiconductor laser device having the quantum well structure as the active layer, the AlAs mixed crystal ratio of the second optical guide layer is set lower than the AlAs mixed crystal ratio of the first optical guide layer. The interface resistance between the second light guide layer and the stripe region can be easily reduced.

Further, since the second light guide layer is transparent to the laser light oscillated by the active layer, heat generation in the vicinity of the active layer is suppressed.

The solution of the invention of claim 6 is In
_0.5 (Ga _1-x Al _x ) _0.5 P active layer, and a first conductivity type In _0.5 (Ga) formed on the active layer.
_1-Y1 Al _Y1 ) _0.5 P optical guide layer and a first conductivity type In _0.5 (Ga _{1 -Y2} ) formed on the optical guide layer.
Al _Y2) and _0.5 and P layer stripe region composed of the optical guide layer _{In 0. 5 (Ga 1-Z} Al Z) 0.5 P layer of a second conductivity type formed on both sides of the stripe region in the top of the Assuming a semiconductor laser device including a current blocking layer, Z> Y2 ≧ X ≧ between X, Y1, Y2 and Z of the respective mixed crystal ratios of the active layer, the light guide layer, the stripe region and the current blocking layer. The relationship of 0 and Y1> X is established, and the stripe region has at least one discontinuous portion in the resonator direction.

With the above structure, the Al in the stripe region is
Since the Al mixed crystal ratio of the current block layer is higher than the mixed crystal ratio, the effective refractive index of the stripe region becomes higher than the effective refractive index outside the stripe region, and a stable single transverse mode by the refractive index guiding mechanism. Oscillation can be obtained.

According to a seventh aspect of the present invention, a means for solving the problems is an active layer having a quantum well structure, and a first conductivity type In _0.5 (Ga _{1 -Y 1} Al _{Y 1} ) _0.5 P layer formed on the active layer. And a first light guide layer formed on the light guide layer.
A stripe region composed of a conductivity type In _0.5 (Ga _{1 -Y 2} Al _{Y 2} ) _0.5 P layer and a second conductivity type In _0.5 formed on both sides of the stripe region on the light guide layer.
(Ga _1-Z Al _Z) a semiconductor laser device having a current blocking layer made of _{0. 5} P layer assumes, the optical guide layer, each mixed crystal ratio of the stripe regions and the current blocking layer Y
The relationship of Z> Y2 ≧ 0 and Y1 ≧ 0 is established between 1, Y2 and Z, and the stripe region has at least one discontinuous portion in the resonator direction. Is.

With the above structure, in the semiconductor laser device in which the active layer has the quantum well structure, the Al mixed crystal ratio of the current block layer is higher than the Al mixed crystal ratio of the stripe region, so that the effective refractive index of the stripe region is higher. Becomes higher than the effective refractive index outside the stripe region, and stable single transverse mode oscillation can be obtained by the refractive index guiding mechanism.

The solution of the invention of claim 8 is In
_0.5 (Ga _1-x Al _x ) _0.5 P active layer, and a first conductivity type In _0.5 (Ga) formed on the active layer.
_1-Y1 Al _Y1 ) _0.5 P first light guide layer, and a first conductivity type In formed on the first light guide layer
_0.5 (Ga _{1 -Y 2} Al _{Y 2} ) _0.5 P 2nd optical guide layer and first conductivity type In _0.5 (Ga _{1 -Y 3} Al _{Y 3} ) ₀ formed on the second optical guide layer _{. 5} P layer stripe region and a second conductivity type In _0.5 (G) formed on both sides of the stripe region on the second optical guide layer.
a _1-Z Al _Z ) _0.5 P layer and a current blocking layer consisting of the current blocking layer, the active layer, the first light guiding layer, the second light guiding layer, the stripe region and the current blocking layer. X, Y1, Y2, Y3 of each mixed crystal ratio of
And Z satisfy the relations of Z>Y3> Y2 ≧ X ≧ 0 and Y1> Y2, and the stripe region has at least one discontinuous portion with respect to the cavity direction. It is a thing.

With the above structure, Al of the second light guide layer is formed.
Since the mixed crystal ratio is lower than that of the first optical guide layer,
The interface resistance between the light guide layer and the stripe region can be easily reduced.

Further, since the second light guide layer is transparent to the laser light oscillated by the active layer, heat generation in the vicinity of the active layer is suppressed.

According to a ninth aspect of the present invention, a means for solving the problems is an active layer having a quantum well structure, and a first conductivity type In _0.5 (Ga _{1 -Y 1} Al _{Y 1} ) _0.5 P layer formed on the active layer. And a first conductivity type In _0.5 (Ga _{1 -Y 2} Al _{Y 2} ) _0.5 P formed on the first light guide layer,
Second light guide layer composed of a layer, and a first conductivity type In _0.5 (Ga _{1 -Y 3} Al _{Y 3} ) layer formed on the second light guide layer.
_A current blocking layer including a stripe region formed of a _0.5 P layer and a second conductivity type In _0.5 (Ga _{1 -Z} Al _Z ) _0.5 P layer formed on both sides of the stripe region on the second optical guide layer. On the premise of a semiconductor laser device including: a first laser beam guide layer, a second laser beam guide layer, a stripe region, and a current block layer having a mixed crystal ratio of Y1, Y2, and Y.
The relations Z>Y3> Y2 ≧ 0 and Y1> Y2 are established between 3 and Z, and the stripe region has at least one discontinuity in the cavity direction. Is.

With the above structure, in the semiconductor laser device in which the active layer has a quantum well structure, the Al mixed crystal ratio of the second optical guide layer is lower than that of the first optical guide layer.
The interface resistance between the second light guide layer and the stripe region can be easily reduced.

Further, since the second light guide layer is transparent to the laser light oscillated by the active layer, heat generation in the vicinity of the active layer is suppressed.

According to a tenth aspect of the present invention, there is provided a method for manufacturing a semiconductor laser device, comprising: an active layer made of a semiconductor layer on a semiconductor substrate by an epitaxial growth method;
The conductivity type Ga _1-Y1 Al _Y1 As layer optical guide layer and the Ga _1-Z Al Z As layer current blocking layer made of the second conductivity type consisting of said Ga _1-Y1 Al _Y1 As layer and Ga _{1- Z} Al _Z
A step of sequentially forming the As layer so that the respective mixed crystal ratios of Y1> 0 and Z> 0 are established; and by selectively etching the current block layer, A step of removing at least one non-removed portion in a stripe shape extending in the cavity direction so as to expose the light guide layer, and a stripe shape in which the current block layer on the light guide layer is removed Of the first conductivity type Ga in the region of
_{The 1-Y2} Al _Y2 As layer is _replaced with the Ga _{1- Z} Al _Z As layer and the G layer.
a _{1-Y 2} Al _{Y 2} As layer is formed so that the relationship of Z> Y 2> 0 is established between the mixed crystal ratios of the a _{1 -Y 2} Al _{Y 2} As layer.

With the above-mentioned structure, after the second conductive type current blocking layer is formed on the first conductive type light guide layer on the active layer, the current blocking layer is discontinuous in the cavity direction by etching. Stripping is performed, and then the first portion is formed on the light guide layer in a region where the current blocking layer is removed.
Since the conductive type region is formed, it is possible to form a stripe region which is discontinuous in the cavity direction on the optical guide layer.

Further, since the effective refractive index of the stripe region formed on the light guide layer is higher than the effective refractive index of the current blocking layer, an effective refractive index difference is formed inside and outside the stripe region. A wave mechanism is obtained.

According to the eleventh aspect of the present invention, there is provided a method for manufacturing a semiconductor laser device, comprising: an active layer formed of a semiconductor layer on a semiconductor substrate by an epitaxial growth method;
A first optical guide layer made of a conductive type Ga _{1 -Y1} Al _Y1 As layer, a second optical guide layer made of a first conductive type Ga _{1 -Y2} Al _Y2 As layer, and a second conductive type Ga _{1 -Z} Al _The current blocking layer made of a _Z As layer is formed of the Ga _{1 -Y 1} Al _{Y 1} As layer and the Ga layer.
Forming a _1-Y2 Al _Y2 As layer and a Ga _1-Z Al _Z As layer so that a relation of Z>Y2>Y1> 0 is established between the respective mixed crystal ratios; Selectively performing etching to remove the current blocking layer in a stripe shape extending in the cavity direction so that at least one non-removed portion remains and the second optical guide layer is exposed; A first conductivity type Ga _{1 -Y 3} Al layer is formed on the second light guide layer in the striped region where the current blocking layer is removed by an epitaxial growth method.
_{The Y 3} As layer is _replaced with the Ga _{1 -Z} Al _Z As layer and the Ga _{1 -Y 3} A layer.
l _Y3 As layer is formed so as to satisfy the relation of Z> Y3 between the respective mixed crystal ratios of the As layer.

According to the above structure, after forming the second conductivity type current block layer on the second light guide layer formed on the first conductivity type first light guide layer on the active layer, Since the current blocking layer is removed by etching in a discontinuous stripe shape in the cavity direction, and then the region of the first conductivity type is formed in the region on the second optical guide layer where the current blocking layer is removed. A stripe region that is discontinuous with respect to the cavity direction can be formed on the two optical guide layers.

Further, since the AlAs mixed crystal ratio of the second light guide layer is set to be lower than the AlAs mixed crystal ratio of the first light guide layer, the interface resistance between the second light guide layer and the stripe region is easy. Since the second light guide layer is transparent to the laser light oscillated by the active layer, heat generation in the vicinity of the active layer is suppressed.

Further, since the effective refractive index of the stripe region formed on the second optical guide layer is higher than the effective refractive index of the current block layer, an effective refractive index difference is formed inside and outside the stripe region, so that refraction is performed. An index guiding mechanism is obtained.

According to a twelfth aspect of the present invention, there is provided a method for manufacturing a semiconductor laser device, wherein an active layer made of a semiconductor layer is formed on a semiconductor substrate by an epitaxial growth method.
An optical guide layer made of a conductive type In _0.5 (Ga _{1 -Y 1} Al _{Y 1} ) _0.5 P layer and a second conductive type In _0.5 (Ga _{1 -Z} A
l _Z ) _0.5 P layer is used as the current blocking layer
_0.5 (Ga _{1 -Y 1} Al _{Y 1} ) _0.5 P layer and In _0.5 (Ga
_1-Y2 Al _Y2 ) _0.5 P between the mixed crystal ratios of Y layer>Y1> 0 and Z
The step of forming so that the relation of> 0 is established, and the current block layer is selectively etched, whereby at least one non-removed portion remains in the current block and the light guide layer is formed. Are removed in a stripe shape extending in the direction of the resonator so as to expose the film, and a first stripe-shaped region on the optical guide layer where the current block layer is removed is formed by an epitaxial growth method.
The conductive In _0.5 (Ga _{1 -Y 2} Al _{Y 2} ) _0.5 P layer is _replaced with the In _0.5 (Ga _{1 -Z} Al _Z ) _0.5 P layer and In _0.5 (G
a _{1-Y 2} Al _{Y 2} ) _0.5 P> Z 2 between the mixed crystal ratios of the P layer
And a step of forming so that the relationship of 1) is established.

According to the structure of claim 12, the first on the active layer is formed.
After forming the second conductive type current block layer on the conductive type light guide layer, the current block layer is removed by etching in the form of discontinuous stripes in the cavity direction. Since the region of the first conductivity type is formed in the region where the current block layer is removed, it is possible to form the stripe region which is discontinuous in the cavity direction on the second optical guide layer.

Further, since the effective refractive index of the stripe region formed on the light guide layer is higher than the effective refractive index of the current block layer, an effective refractive index difference is formed inside and outside the stripe region. The mechanism is obtained.

According to a thirteenth aspect of the present invention, there is provided a method for manufacturing a semiconductor laser device, comprising: an active layer made of a semiconductor layer on a semiconductor substrate by an epitaxial growth method;
A first optical guide layer made of a conductive type In _0.5 (Ga _{1 -Y 1} Al _{Y 1} ) _0.5 P layer and a first conductive type In _0.5 (Ga _{1 -Y 2} Al)
_{Y2) 0.5} P consisting layer second optical guide layer and the second conductive type _{In 0.5 (Ga 1-Z Al} Z) a current blocking layer made of _0.5 P layer, the _{In 0. 5 (Ga 1-Y1} Al Y1 ) _0.5 P layer,
In _0.5 (Ga _{1 -Y 2} Al _{Y 2} ) _0.5 P layer and In _0.5 (G
a _1-Z Al _Z ) _0.5 P between the mixed crystal ratios of the P layer, Z> Y 2 ≧ 0
And Y1> Y2, and at least one non-removed portion remains in the current block layer by selectively etching the current block layer. A step of removing the second optical guide layer in a stripe shape extending in the cavity direction so as to be exposed, and an epitaxial growth method in a stripe-shaped region on the second optical guide layer where the current block layer has been removed. First conductivity type In _0.5 (Ga _{1 -Y 3} A
l _Y3 ) _0.5 P layer is _{replaced with} In _0.5 (Ga _{1 -Z} Al _Z ).
_And a step of forming such that the relation of Z> Y3 is established between the respective mixed crystal ratios of the _0.5 P layer and the In _0.5 (Ga _{1 -Y3} Al _Y3 ) _0.5 P layer.

According to the above structure, after forming the second conductive type current blocking layer on the second optical guide layer formed on the first conductive type first optical guide layer on the active layer, Since the current blocking layer is removed by etching in a discontinuous stripe shape in the cavity direction, and then the region of the first conductivity type is formed in the region on the second optical guide layer where the current blocking layer is removed. A stripe region that is discontinuous with respect to the cavity direction can be formed on the two optical guide layers.

The Al mixed crystal ratio of the second optical guide layer is set to the first
Since it is lower than the Al mixed crystal ratio of the light guide layer,
The interface resistance between the light guide layer and the stripe region can be easily reduced, and since the second light guide layer is transparent to the laser light oscillated by the active layer, heat generation in the vicinity of the active layer does not occur. Suppressed.

Further, since the effective refractive index of the stripe region formed on the second optical guide layer is higher than the effective refractive index of the current block layer, an effective refractive index difference is formed inside and outside the stripe region, so that refraction is performed. An index guiding mechanism is obtained.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a semiconductor laser device according to the first embodiment of the present invention. A buffer layer 2 made of n-type GaAs on a semiconductor substrate 1 made of n-type GaAs
And n-type Ga _0.45 Al is formed on the buffer layer 2.
The first clad layer 3 consisting of _0.55 As layer is formed,
An active layer 4 made of a Ga _0.85 Al _0.15 As layer is formed on the clad layer 3, and a p-type Ga _0.45 Al layer is formed on the active layer 4.
The first light guide layer 5 consisting of _0.55 As layer is formed, and
A second light guide layer 6 made of a p-type Ga _0.8 Al _0.2 As layer is formed on the light guide layer 5. In addition, a p-type Ga that serves as a current channel is formed on the second light guide layer 6.
_A stripe region 7a made of a _0.45 Al _0.55 As layer is formed, and the stripe region 7 on the second light guide layer 6 is formed.
In regions other than a, n-type Ga _0.3 Al _{0.7 is used} to confine light in the stripe region 7a and constrict current.
A current blocking layer 7 made of an As layer is formed.

As a feature of the first embodiment, the stripe region 7a is formed in a discontinuous shape with respect to the cavity direction, and like the current block layer 7, it is an n-type Ga _0.3 Al.
_It has a discontinuous portion 7b made of a _0.7 As layer.

Current blocking layer 7 and stripe region 7a
A second clad layer 8 made of p-type Ga _0.45 Al _0.55 As is formed on the above, and a contact layer 9 made of p-type GaAs is formed on the second clad layer 8.

In the first embodiment, in order to obtain stable single transverse mode oscillation, the AlAs mixed crystal ratio of the current blocking layer 7 is set higher than the AlAs mixed crystal ratio of the second cladding layer 8. If the AlAs mixed crystal ratio of the current block layer 7 is the second
When the AlAs mixed crystal ratio of the cladding layer 8 is the same, there is a decrease in the refractive index in the stripe region 7a due to the plasma effect, and it is difficult to obtain a single transverse mode oscillation. Therefore, in the first embodiment, as described above, the AlAs mixed crystal ratio of the current block layer 7 is set higher than the AlAs mixed crystal ratio of the second cladding layer 8 and set to 0.7.

According to this structure, the current injected from the contact layer 9 is confined in the stripe region 7a, and laser oscillation in the 780 nm band occurs in the active layer 4 below the stripe region 7a. In the first embodiment, the first
The AlAs mixed crystal ratio of the optical guide layer 5 is made sufficiently higher than the AlAs mixed crystal ratio of the active layer 4 to effectively confine carriers in the active layer 4 and enable oscillation in the visible range. Specifically, in order to obtain laser oscillation in the 780 nm band, the AlAs mixed crystal ratio of the first optical guide layer 5 needs to be 0.45 or more, and is set to 0.55 in this embodiment. .

The AlAs mixed crystal ratio of the second optical guide layer 6 which facilitates regrowth and acts as an etching stop layer is preferably transparent to the oscillation wavelength of the laser. Therefore, in the first embodiment, the AlAs mixed crystal ratio of the second light guide layer 6 is set to 0.2.

The film thickness of the second light guide layer 6 is preferably 0.05 μm or less, which is a film thickness that does not significantly affect the light distribution, and is therefore 0.03 μm in the first embodiment.

Further, since the forbidden band width of the current block layer 7 is larger than the forbidden band width of the active layer 4, there is no light absorption by the current block layer 7 and a semiconductor laser device of low operating current with small waveguide loss is provided. can get.

According to the structure of the first embodiment, the current is confined by the current blocking layer 7 in the stripe region 7a which is discontinuous in the resonator direction. In this case, the active layer 4
Since the supply of carriers is limited in the region below the discontinuous portion 7b of the stripe region 7a in, the light is supplied by the seeping from the active layer 4 below the stripe region 7a. Therefore, the discontinuous portion 7b in the active layer 4
The lower region acts as a saturable absorption region. Here, the effective refractive index difference in the horizontal direction required for stabilizing the transverse mode is determined by the effective refractive index difference inside and outside the stripe region 7a, and even if the effective refractive index difference is increased, the volume of the saturable absorption region is not so large. does not change. The volume of the saturable absorption region can be changed by changing the length of the discontinuous portion 7b of the stripe region 7a in the cavity direction, and even if the thin active layer 4 suitable for high output operation has a large volume, the saturable absorption region is large. Can be formed.

As described above, according to the semiconductor laser device of the first embodiment, the saturable absorption region can be locally formed in the cavity direction while keeping the effective refractive index difference in the horizontal direction large. You can easily get self-pulsation. That is, it is possible to realize a low-noise semiconductor laser device with a stable transverse mode and a small astigmatic difference even during high-power operation.

When the length of the discontinuous portion 7b of the stripe region 7a in the cavity direction is increased, the volume of the saturable absorption region formed in the active layer 4 is increased, and the current-light output characteristic has a hysteresis-like characteristic, That is, bistability can be obtained.

Specifically, in order to obtain a stable transverse mode even at the time of high output operation, the effective refractive index difference inside and outside the stripe region 7a needs to be 6 × 10 ⁻³ or more. Further, even if the light density at the laser end face is reduced and the device is operated at high output, the laser end face is destroyed by its own light.
In order to prevent (catastrophic optical damage), it is preferable that the thickness of the active layer 4 is thin, and specifically, it is necessary to set it to 40 nm or less.

FIG. 2 shows the length of the discontinuous portion 7b of the stripe region 7a and the layer thickness of the first optical guide layer 5, the optical characteristics during laser oscillation, and the stripe region 7a in the laser device according to the first embodiment. The experimental result of the relationship with the effective refractive index difference inside and outside is shown. The thickness of the active layer 4 is 35 nm, which is suitable for high output operation. When the effective refractive index difference between the inside and outside of the stripe region 7a is 6 × 10 ⁻³ , the length (L _h ) in the cavity direction of the discontinuous portion 7b of the stripe region 7a is 2 μm to 1
It can be seen that self pulsation occurs in the range of 0 μm. Further, the length (L _h ) of the discontinuous portion 7b of the stripe region 7a in the cavity direction is 10 μm to 23 μm.
It can be seen that bistability can be obtained as the current and light output in the range.

As described above, in the first embodiment, the effective refractive index difference between the inside and the outside of the stripe region 7a required to obtain a stable transverse mode is 6 × 10 ⁻³ or more, and high output operation is possible. Even a suitable thin active layer 4 can cause self-pulsation.

According to the conventional structure, the saturable absorption region is
Since the active layer 4 is formed on the lower side of the current block layer 7 on both sides of the stripe region 7a, a loss occurs in the region of the active layer 4 below the current block layer 7, and the lower side of the current block layer 7 is guided. The phase of the lasing laser light is the stripe region 7
It is delayed with respect to the phase of the laser light guided in the lower side of a. Therefore, when the laser light is converged by the lens, an astigmatic difference in focal length between the direction parallel to the active layer 4 and the direction perpendicular to the active layer 4 occurs. There was a problem of being lost.

However, according to the first embodiment, the saturable absorption region is formed in the direction perpendicular to the direction of the resonator,
Since self-pulsation is generated in a state where the equiphase surface is not curved, it is possible to realize a low-noise semiconductor laser with a small astigmatic difference.

FIG. 3 is a sectional view showing each step of the method for manufacturing the semiconductor laser device according to the first embodiment.

First, as shown in FIG. 3A, n-type G
On the semiconductor substrate 1 made of an aAs layer, a buffer layer 2 made of an n-type GaAs layer and having a thickness of 0.5 μm, and an n-type Ga _0.45 Al _0.55 A are formed by MOCVD or MBE growth.
The first clad layer 3 made of s layer and having a thickness of 1.5 μm, G
a _0.85 Al _0.15 As layer of 0.035 μm thick active layer 4, p-type Ga _0.45 Al _0.55 As layer of 0.1 μm thick first optical guide layer 5, p-type Ga _0.8 Al
The second optical guide layer 6 having a thickness of 0.03 μm, which is a _0.2 As layer, and the thickness 1.0, which is an n-type Ga _0.3 Al _0.7 As layer.
The current blocking layer 7 having a thickness of μm is sequentially formed. The active layer 4
The conductivity type is not particularly limited, and may be p-type, n-type, or, of course, undoped.

Next, as shown in FIG. 3B, a stripe region 7a having a discontinuous portion 7b in the cavity direction is formed by etching using a photolithography technique. As the etching method, tartaric acid, which has a low selectivity with respect to the AlAs mixed crystal ratio, is used as an etchant, and etching is performed up to the middle of the current block layer 7. Next, the current block layer 7 is selectively etched using an etchant capable of selectively etching a layer having a high AlAs mixed crystal ratio, such as a hydrofluoric acid-based or phosphoric acid-based layer. In this case, the second
The light guide layer 6 also functions as an etching stop layer. Therefore, variation due to etching is small, and high yield can be obtained. In addition, in the first embodiment, the stripe width of the stripe region 7a is set to 3.0 μm, and the length of the discontinuous portion 7b is set to 5 μm.

Here, the cross-sectional shape of the stripe region 7a is preferably a forward mesa shape with respect to the second cladding layer 8 rather than an inverted mesa shape. The reason is as follows. That is, in the case where the second clad layer 8 has an inverted mesa shape, crystal growth becomes difficult as compared with the case where the second mesa shape has a normal mesa shape, and there is a possibility that yield may be reduced due to deterioration of characteristics. is there. In fact, in the case of the inverted mesa shape with respect to the second cladding layer 8, the crystallinity of GaAlAs grown on the side portion of the stripe region 7a is impaired, and the threshold current of the manufactured semiconductor laser device has a normal mesa shape. It was about 10 mA higher than that of the device of FIG. The characteristics of the semiconductor laser device, which will be described later, show that the second cladding layer 8 has a forward mesa shape.

Regarding the film thickness of the current block layer 7, if the current block layer 7 is thin, light absorption of the laser beam will occur in the upper contact layer 9, and the effective inside and outside of the stripe region 7a will occur. Since the difference in refractive index is small, a thickness of 0.5 μm or more is necessary.

Next, as shown in FIG. 3C, MOCV
The p-type Ga _0.45 Al _0.55 A is formed on the stripe region 7a and the current block layer 7 by the D or MBE growth method.
The clad layer 8 made of s and the contact layer 9 made of p-type GaAs are sequentially formed by regrowth. At this time,
Since the stripe region 7a through which the current flows is grown on the second optical guide layer 6 having a low AlAs mixed crystal ratio, the growth is easily performed. However, when Zn is used as the dopant for the second cladding layer 8, there is an influence on the characteristics due to diffusion of Zn during the growth into the stripe region 7a, so that the carrier concentration is set to 10 at least at the regrowth interface. ^It needs to be ¹⁸ cm ⁻³ or less, and in the first embodiment, it is 7 × 10 ¹⁷ cm ⁻³ . Of course, a low diffusive dopant such as carbon may be used. Finally,
Electrodes (not shown) are formed on the semiconductor substrate 1 and the contact layer 9, respectively.

FIG. 4 is a current-light output characteristic diagram of the semiconductor laser device according to the first embodiment. As shown in FIG. 4, 100 mW is obtained as the maximum light output. The length of the resonator is 400 μm, and the discontinuous portion 7 of the stripe region 7a is
In the semiconductor laser device in which the length of b is 5 μm, the operating current value required to emit a laser beam of 35 mW at room temperature is 75 mA. At an optical output of 3 mW, the spectrum oscillates in multiple modes causing self-pulsation in the 780 nm band, and within the range of 0 to 10% of the returning light rate,
A value of RIN of 135 dB / Hz is obtained, and low noise characteristics sufficient for application to an optical disc are obtained.

FIG. 5 shows the optical output dependence of the horizontal divergence angle in the semiconductor laser device according to the first embodiment.
In the conventional low noise laser, in order to obtain self-pulsation, it is necessary to widely spread the light distribution to the outside of the stripe region 7a and form the saturable absorption region in the active layer 4 below the current block layer 7 largely. Therefore, the effective refractive index difference must be reduced to 4 × 10 ⁻³ or less.
For this reason, the plasma effect causes a decrease in the refractive index inside the stripe region 7a due to the injection current and changes the light distribution, which causes a problem that the horizontal spread angle largely changes due to an increase in the light output. On the other hand, in the first embodiment, since the saturable absorber for obtaining self-pulsation is formed in the region below the discontinuous portion 7b of the stripe region 7a in the active layer 4, the stripe region 7a is formed.
Even if the effective refractive index difference is large enough to obtain a stable light distribution that is not affected by the decrease in the refractive index inside the stripe region 7a due to the plasma effect of 6 × 10 ⁻³ as the effective refractive index difference between the inside and the outside, self-pulsation is performed. It is possible to obtain a stable basic transverse mode without changing the horizontal divergence angle largely due to the change of the light output.

FIG. 6 shows the optical output dependence of the astigmatic difference in the semiconductor laser device according to the first embodiment. In the conventional low noise laser, since the saturable absorption region is formed in the active layer 4 below the current block layer 7 on both sides of the stripe region 7a, the loss in the region below the current block layer 7 in the active layer 4 is lost. Occurs, the phase of the laser light guided below the current blocking layer 7 lags behind the phase of the laser light guided below the stripe region 7a. For this reason,
The astigmatic difference is 20 μm due to the curvature of the isophase surface of the laser beam.
In addition, the loss of the active layer 4 below the current blocking layer 7 significantly changes due to the current injection, so that there is a problem that the astigmatic difference also largely changes due to the optical output. On the other hand, in the first embodiment, since the saturable absorption region for obtaining self-pulsation is formed in the region below the discontinuous portion 7b of the stripe region 7a in the active layer 4, the curve of the equiphase surface is curved. The astigmatic difference is extremely small regardless of the light output, and can be greatly reduced to within 2 μm.

When a low noise and high output semiconductor laser device having such a small astigmatic difference is used as a light source of an optical disc, a high frequency superimposing circuit for reducing noise at the time of reading and an astigmatic difference are corrected. The lens is unnecessary, and the size and cost of the pickup head device can be greatly reduced.

The semiconductor laser device according to the second embodiment of the present invention will be described below.

In the second embodiment, the active layer 4 in the first embodiment has a quantum well structure, which makes it possible to reduce the threshold value and obtain a high output. As a quantum well structure, four well layers made of Ga _0.95 Al _0.05 As having a thickness of 10 nm and oscillating in a 780 nm band, and 4
A multiquantum well (MQW) structure including five barrier layers of Ga _0.7 Al _0.3 As with a thickness of nm is used.

FIG. 7 shows current-light output characteristics in the semiconductor laser device according to the second embodiment. As shown in FIG. 7, in the second embodiment, the transverse mode did not change and was stable, and an optical output of 150 mW or more was obtained. Furthermore, at an optical output of 3 mW, the spectrum oscillates in multiple modes that cause self-pulsation in the 780 nm band, and within the range of the return light rate of 0 to 10%, -135 dB / H.
The RIN value of z was obtained, and low noise characteristics were obtained. Also, the astigmatic difference was sufficiently small and a value of 2 μm or less was obtained.
Such a semiconductor laser device with low astigmatism, low noise, and ultrahigh output has not been possible with the conventional structure.

As the structure of the active layer 4, another quantum well structure, for example, a single quantum well (SQW) structure,
A double quantum well (DQW) structure, a triple quantum well (TQW) structure, a grin (GRIN) structure or a separate confinement heterostructure (SCH) structure thereof may be used.

In the first or second embodiment, the semiconductor substrate 1 is n-type, and only the case where the n-type current block layer 7 is used is shown. However, the semiconductor substrate 1 is p-type. The p-type current blocking layer 7 may be used. The reason is that the AlAs mixed crystal ratio of the current block layer 7 is high. That is, p-type GaA having a high AlAs mixed crystal ratio
This is because in the case of the 1As layer, the diffusion of electrons is suppressed, so that the p-type current blocking layer 7 can be realized.

The semiconductor laser device according to the third embodiment of the present invention will be described below.

The third embodiment is a red semiconductor laser device using an InGaAlP based semiconductor substrate.

FIG. 8 is a sectional view of a semiconductor laser device according to the third embodiment of the present invention. On the semiconductor substrate 11 made of n-type GaAs, n-type In _0.5 (Ga _0.4 A
l _0.6) first cladding layer 12 made of _{0. 5} P is formed, an active layer 13 made of InGaP on the first cladding layer 12 is formed, the p-type on the active layer 13 an In
_0.5 (Ga ^{0. 4} Al _0.6) first optical guide layer 14 of _0.5 P is formed, p-type I on the first optical guide layer 14
A second optical guide layer 15 made of n _0.5 (Ga _0.9 Al _0.1 ) _0.5 P is formed. In addition, the second light guide layer 15
On the upper side is a p-type In _0.5 (Ga
_A stripe region 16a made of _0.4 Al _0.6 ) _0.5 is formed, and n-type In for confining light in the stripe region 16a and confining a current is formed in a region other than the stripe region 16a on the second light guide layer 6.
_{0. 5} (Ga _0.25 Al _0.75) current blocking layer 16 of _0.5 P layer is formed.

A feature of the third embodiment is that the stripe region 16a is formed in a discontinuous shape with respect to the cavity direction, and like the current block layer 16, it is an n-type In _0.5.
(Ga _0.25 Al _0.75 ) _0.5 Discontinuous portion 16b made of P layer
have.

Current blocking layer 16 and stripe region 1
On top of 6A, p-type In _0.5 (Ga _0.4 Al _0.6 ) _{0.5 is formed.}
A second cladding layer 17 made of P is formed, and a contact layer 18 made of p-type GaAs is formed on the second cladding layer 17.

In the third embodiment, in order to obtain stable single transverse mode oscillation, the Al mixed crystal ratio of the current block layer 16 is set higher than the Al mixed crystal ratio of the second cladding layer 17. If the Al mixed crystal ratio of the current block layer 16 is the same as the Al mixed crystal ratio of the second cladding layer 17, there is a decrease in the refractive index in the stripe region 16a due to the plasma effect, and a single transverse mode oscillation occurs. Hard to get. Therefore, in the third embodiment, as described above, the Al mixed crystal ratio of the current blocking layer 16 is set to 0.75, which is 0.15 higher than the Al mixed crystal ratio of the second cladding layer 17. .

According to this structure, the current injected from the contact layer 18 is confined in the stripe region 16a,
68 in the active layer 13 below the stripe region 16a
Laser oscillation in the 0 nm band occurs. In the third embodiment, the Al mixed crystal ratio of the first light guide layer 14 is set to A of the active layer 13.
L is sufficiently higher than the mixed crystal ratio, and carriers are added to the active layer 13
It effectively locks in and enables oscillation in the visible range.

The Al mixed crystal ratio of the second optical guide layer 15 which facilitates regrowth and acts as an etching stop layer is preferably transparent to the oscillation wavelength of the laser. Therefore, in the third embodiment, the Al mixed crystal ratio of the second light guide layer 15 is 0.1.

Since the film thickness of the second light guide layer 15 is preferably 0.05 μm or less, which is a film thickness that does not significantly affect the light distribution, it is 0.03 μm in the second embodiment.

Further, since the forbidden band width of the current block layer 16 is larger than the forbidden band width of the active layer 13, there is no light absorption by the current block layer 16 and a semiconductor laser device of low operating current with small waveguide loss is provided. can get.

Also in the structure of the second embodiment, the current is confined by the current blocking layer 16 in the stripe region 16a which is discontinuous in the resonator direction. In this case, the discontinuous portion 16 of the stripe region 16a in the active layer 13
Since the supply of carriers is limited in the region below b, light is supplied by the seeping from the active layer 13 below the stripe region 16a. Therefore, the region below the discontinuous portion 16b in the active layer 13 acts as a saturable absorption region. Here, the effective refractive index difference in the horizontal direction necessary for stabilizing the transverse mode is determined by the effective refractive index difference inside and outside the stripe region 16a, and even if the effective refractive index difference is increased, the volume of the saturable absorption region is not so large. does not change. The volume of the saturable absorption region is the discontinuous portion 16 of the stripe region 16a.
It can be changed depending on the length of b in the cavity direction, and a saturable absorption region having a large volume can be formed even with a thin active layer 13 suitable for high-power operation.

As described above, according to the semiconductor laser device of the third embodiment, the saturable absorption region can be locally formed in the cavity direction while keeping the effective refractive index difference in the horizontal direction large. You can easily get self-pulsation. That is, it is possible to realize a low-noise semiconductor laser device with a stable transverse mode and a small astigmatic difference even during high-power operation.

When the length of the discontinuous portion 16b of the stripe region 16a in the cavity direction is increased, the volume of the saturable absorption region formed in the active layer 13 is increased, and the current-light output characteristic has a hysteresis-like characteristic, That is, bistability can be obtained.

Specifically, in order to obtain a stable transverse mode even at the time of high output operation, it is necessary that the effective refractive index difference inside and outside the stripe region 16a is 6 × 10 ⁻³ or more.
Further, even if the light density at the laser end face is reduced and the device is operated at high output, the laser end face is destroyed by its own light.
In order to prevent the occurrence of the above, it is preferable that the thickness of the active layer 13 is thin, and specifically, it is necessary to set it to 40 nm or less.

FIG. 9 shows the length of the discontinuous portion 16b of the stripe region 16a and the layer thickness of the first optical guide layer 14, the optical characteristics during laser oscillation, and the stripe region 16a in the laser device according to the third embodiment. The experimental result of the relationship with the effective refractive index difference inside and outside is shown. The thickness of the active layer 13 is set to 35 nm, which is suitable for high output operation. Stripe area 1
When the effective refractive index difference between the inside and the outside of 6a is 6 × 10 ⁻³ , the length of the discontinuous portion 16b of the stripe region 16a in the cavity direction (L
It can be seen that _hr ) causes self pulsation in the range of 2.5 μm to 8 μm. Further, it is understood that when the length (L _hr ) of the discontinuous portion 16b of the stripe region 16a in the cavity direction is in the range of 8 μm to 20 μm, bistable current light output can be obtained.

As described above, in the first embodiment, the stripe region 16a necessary for obtaining a stable transverse mode is obtained.
The effective refractive index difference between inside and outside is 6 × 10 ⁻³ or more, and
Even a thin active layer 13 suitable for high power operation can cause self-pulsation.

According to the conventional structure, the saturable absorption region is
Since it is formed in the active layer 13 below the current block layer 16 on both sides of the stripe region 16a, loss occurs in the region below the current block layer 16 in the active layer 13, and the region below the current block layer 16 is guided. The phase of the lasing laser light lags behind the phase of the laser light guided below the stripe region 16a. For this reason, when the laser light is converged by the lens due to the curvature of the equiphase surface of the laser light,
There is a problem that an astigmatic difference occurs in the focal lengths of the direction parallel to the active layer 4 and the direction perpendicular to the active layer 4.

However, according to the third embodiment, the saturable absorption region is formed in the direction perpendicular to the direction of the resonator,
Since self-pulsation is generated in a state where the equiphase surface is not curved, it is possible to realize a low-noise semiconductor laser with a small astigmatic difference.

FIG. 10 is a sectional view showing each step of the method for manufacturing the semiconductor laser device according to the third embodiment.

First, as shown in FIG. 10A, n-type In _0.5 (Ga _0.4 A) is formed on a semiconductor substrate 11 made of n-type GaAs by MOCVD or MBE growth.
l _{0. 6) 0.5} the first cladding layer 12 having a thickness of 1.5μm made of, the active layer 13 having a thickness of 0.035μm consisting InGaP, p-type In _0.5 (Ga _0.4 Al _0.6) and _0.5 thickness 0 0.07 μm first optical guide layer 14, p-type In
_0.5 (Ga _0.9 Al _{0. 1)} consisting of _0.5 P thickness 0.03
μm second optical guide layer 15, n-type In _0.5 (Ga _0.25
A current blocking layer 16 made of Al _0.75 ) _0.5 P and having a thickness of 1.0 μm is sequentially formed. The conductivity type of the active layer 13 is
There is no particular limitation, and it may be p-type, n-type, or of course undoped.

Next, as shown in FIG. 10B, a stripe region 16a having a discontinuous portion 16b in the cavity direction is formed by etching using a photolithography technique. As an etching method, tartaric acid, which has a low selectivity with respect to the Al mixed crystal ratio, is used as an etchant, and etching is performed up to the middle of the current block layer 16. Next, the current block layer 16 is selectively etched using an etchant capable of selectively etching a layer having a high Al mixed crystal ratio such as a hydrofluoric acid type or a phosphoric acid type. In this case, the second
The light guide layer 15 also functions as an etching stop layer. Therefore, the variation due to etching is small,
High yield can be obtained. In addition, in the third embodiment, the stripe width of the stripe region 16a is set to 3.0 μm, and the length of the discontinuous portion 16b is set to 5 μm.

Here, the cross-sectional shape of the stripe region 16a is preferably a forward mesa shape with respect to the second cladding layer 17 rather than an inverted mesa shape. The reason is as follows. That is, in the case where the second clad layer 17 has an inverted mesa shape, crystal growth becomes difficult as compared with the case where the second mesa shape is formed, and there is a possibility that the yield may be reduced due to the deterioration of the characteristics. is there. In fact, the second cladding layer 1
In the case of the inverted mesa shape with respect to 7, the crystallinity of InGaAlAs grown on the side of the stripe region 16a is impaired, and the threshold current of the manufactured semiconductor laser device is
It was about 30 mA higher than that of the element having a normal mesa shape. The characteristics of the semiconductor laser device described later are as follows:
In contrast, a forward mesa shape is shown.

Regarding the film thickness of the current block layer 16, if the current block layer 16 is thin, the upper contact layer 18 absorbs laser light,
Further, since the difference in effective refractive index between the inside and outside of the stripe region 16a becomes small, a thickness of 0.5 μm or more is required.

Next, as shown in FIG. 10C, the MOC
Stripe region 16 by VD or MBE growth method
a and p-type In _0.5 (G
a _{0. 4} Al _0.6) consisting of _0.5 P cladding layer 17 and p
A contact layer 18 made of GaAs of the same type is formed by regrowth. At this time, the stripe region 16 through which the current flows
Since a is grown on the second optical guide layer 15 having a low Al mixed crystal ratio, the growth is easily performed. However,
When Zn is used as the dopant of the second cladding layer 17, there is an influence on the characteristics due to diffusion of Zn into the stripe region 16a during growth, so that the carrier concentration is at least 10 ¹⁸ cm ⁻ at the regrowth interface. ^It must be ³ or less, and in the third embodiment, it is 7 × 10 ¹⁷ cm ⁻³ . Of course, a low diffusive dopant such as carbon may be used. Finally, electrodes (not shown) are formed on the semiconductor substrate 11 and the contact layer 18, respectively.

FIG. 11 is a current-light output characteristic diagram of the semiconductor laser device according to the third embodiment. As shown in FIG. 11, 70 mW is obtained as the maximum light output. In a semiconductor laser device in which the length of the resonator is 400 μm and the length of the discontinuous portion 16b of the stripe region 16a is 5 μm, the operating current value required to emit laser light of 35 mW at room temperature is 80 mA. At an optical output of 3 mW, the spectrum oscillates in a multimode that causes self-pulsation in the 680 nm band, and the RIN value of -135 dB / Hz is obtained within the range of the return light rate of 0 to 10%. A low noise characteristic sufficient for application is obtained.

FIG. 12 shows the optical output dependence of the horizontal spread angle in the semiconductor laser device according to the third embodiment. In the conventional low noise laser, in order to obtain self-pulsation, the light distribution is largely expanded outside the stripe region 16a, and the saturable absorption region is formed in the current blocking layer 16.
Since it is necessary to form a large size in the lower active layer 13,
The effective refractive index difference had to be reduced to 4 × 10 ⁻³ or less. For this reason, the plasma effect causes a decrease in the refractive index inside the stripe region 7a due to the injection current and changes the light distribution, which causes a problem that the horizontal divergence angle largely changes due to an increase in the light output. On the other hand, in the third embodiment, since the saturable absorber for obtaining self-pulsation is formed in the region below the discontinuous portion 16b of the stripe region 16a in the active layer 13,
6 × 1 as the effective refractive index difference between the inside and outside of the stripe region 16a
Even if the effective refractive index difference is large enough to obtain a stable light distribution that is not affected by the decrease in the refractive index inside the stripe region 16a due to the plasma effect of 0 ^−3, the self-pulsation can be obtained, and the change in the optical output can be achieved. As a result, the horizontal divergence angle does not change significantly, and a stable basic transverse mode can be obtained.

FIG. 13 shows the optical output dependence of the astigmatic difference in the semiconductor laser device according to the third embodiment. In the conventional low noise laser, the saturable absorption region is formed on the active layer 1 below the current block layer 16 on both sides of the stripe region 16a.
3, the loss is generated in the region below the current blocking layer 16 in the active layer 13, and the current blocking layer 1
The phase of the laser light guided below 6 is the stripe region 1
6a is delayed with respect to the phase of the laser light guided below. Therefore, the isophase plane of the laser beam is curved, the astigmatic difference increases to 20 μm, and further, the loss of the active layer 13 below the current block layer 16 largely changes due to the current injection. However, there is a problem in that the light output greatly changes. On the other hand, in the third embodiment, since the saturable absorption region for obtaining self-pulsation is formed in the region below the discontinuous portion 16b of the stripe region 16a in the active layer 13, the curvature of the equiphase surface is curved. The astigmatic difference is extremely small regardless of the light output, and can be greatly reduced to within 2 μm.

When a low-noise and high-output semiconductor laser device having a small astigmatic difference having such a structure is used as a light source for an optical disk, a high-frequency superimposing circuit for reducing noise during reading and an astigmatic difference are corrected. The lens is unnecessary, and the size and cost of the pickup head device can be greatly reduced.

The semiconductor laser device according to the fourth embodiment of the present invention will be described below.

In the fourth embodiment, the active layer 13 in the third embodiment has a quantum well structure, which makes it possible to reduce the threshold value and obtain a high output. As a quantum well structure, three well layers made of InGaP having a thickness of 10 nm and oscillating in the 630 nm band and four barrier layers made of In _0.5 (Ga _0.5 Al _0.5 ) _0.5 P having a thickness of 4 nm are used. The following multiquantum well (MQW) structure is used.

FIG. 14 shows current-light output characteristics in the semiconductor laser device according to the fourth embodiment. As shown in FIG. 14, in the fourth embodiment, the transverse mode did not change and was stable, and an optical output of 100 mW or more was obtained. Further, at an optical output of 3 mW, the spectrum oscillates in a multimode that causes self-pulsation in the 630 nm band, and within the range of 0 to 10% of the return light rate, -135 dB /
The RIN value of Hz was obtained, and low noise characteristics were obtained.
Also, the astigmatic difference was sufficiently small and a value of 2 μm or less was obtained. Such a semiconductor laser device with low astigmatism, low noise, and ultrahigh output has not been possible with the conventional structure.

As the structure of the active layer 13, another quantum well structure, for example, a single quantum well (SQW) structure, a double quantum well (DQW) structure, a triple quantum well (TQW) structure, a grin (GRIN) structure, or a structure thereof is used. A separate confinement heterostructure (SCH) structure or the like may be used.

In the third or fourth embodiment, the semiconductor substrate 11 is n-type and only the case where the n-type current blocking layer 16 is used is shown. However, the semiconductor substrate 11 is p-type. The p-type current blocking layer 16 may be used.

Further, the semiconductor laser device having the above-mentioned structure is manufactured by using InP-based, InGaAsP-based, InGaAl.
P-based, GaN-based, InGaN-based, AlGaN-based or Zn
It is needless to say that a semiconductor laser device having a small astigmatic difference in other wavelength regions, stable low lateral mode noise, and high output can be realized by using another compound semiconductor material such as Se system.

Further, in each of the above-mentioned embodiments, the length of the discontinuous portion of the stripe region is 5 μm, but instead of this, the length of the discontinuous portion of the stripe region is 10 μm.
As described above, the semiconductor lasers which produce the bistable characteristics in the current and light output characteristics are AlGaAs type, InP type, InGaAsP
System, InGaAlP system, GaN system, InGaN system, Al
It goes without saying that it can be obtained using a compound semiconductor material such as GaN-based or ZnSe-based.

[0118]

According to the GaAlAs semiconductor laser device of the first aspect of the present invention, a self-pulsation or bistable characteristic is generated in the current light output characteristic below the discontinuous portion of the stripe region in the active layer. It is possible to form the saturable absorption region necessary for this. Since the volume of this saturable absorption region can be controlled by the length of the discontinuous portion of the stripe region, even if it is a thin active layer suitable for obtaining high output characteristics, high output power that causes self-pulsation is generated. A semiconductor laser device can be obtained with a high yield.

A semiconductor laser device capable of high-power operation and causing self-pulsation is important as a light source for a rewritable optical disc. Due to self-pulsation, the oscillation spectrum during laser oscillation becomes multimode, and low noise characteristics that are not affected by the reflected light from the optical disk can be obtained. Therefore, the high-frequency current that was conventionally required to make the oscillation spectrum multimode is superimposed. Since no circuit is required, the optical pickup head device can be greatly reduced in size and cost.

GaAlAs according to the invention of claim 2 or 3
According to the semiconductor laser device of the system, the AlAs mixed crystal ratio of the second conductivity type current block layer is higher than the AlAs mixed crystal ratio of the first conductivity type stripe region, and the light absorption of the laser light in the current block layer is significantly increased. Therefore, in the semiconductor laser according to claim 1, a semiconductor laser device having a low operating current value, a small astigmatic difference, and a stable lateral mode from a low output to a high output operation can be easily provided. Can be obtained. For this reason, an optical component for correcting the astigmatic difference is not required, so that the optical pickup head device can be simplified and reduced in cost.

In particular, according to the third aspect of the invention, since the active layer has the quantum well structure, a low-noise semiconductor laser device having a stable transverse mode and a small astigmatic difference can be obtained up to a high output of 100 mW.

GaAlAs according to the invention of claim 4 or 5
According to the semiconductor laser device of the system, Al of the second optical guide layer is
Since the As mixed crystal ratio is lower than that of the first optical guide layer,
The interface resistance between the second light guide layer and the stripe region can be easily reduced, and the second light guide layer is transparent to the laser light oscillated by the active layer. Heat generation is suppressed.

Therefore, it is possible to achieve high output and long life of the semiconductor laser device having low operating current, low astigmatism and low noise.

InGaAl according to the invention of claim 6 or 7
According to the P-based semiconductor laser device, the Al mixed crystal ratio of the second conductivity type current block layer becomes higher than the Al mixed crystal ratio of the first conductivity type stripe region, and the light absorption of the laser light in the current block layer is prevented. A semiconductor laser device having a low operating current value, a small astigmatic difference, and a stable transverse mode from low output to high output operation in the semiconductor laser according to claim 1 because it can be greatly reduced. Can be easily obtained. For this reason, an optical component for correcting the astigmatic difference is not required, so that the optical pickup device can be simplified and the cost can be reduced.

In particular, according to the invention of claim 7, since the active layer has a quantum well structure, a low-noise semiconductor laser device having a stable transverse mode and a small astigmatic difference can be obtained up to a high output of 100 mW.

InGaAl according to the invention of claim 8 or 9
According to the P-based semiconductor laser device, A of the second optical guide layer is
Since the l mixed crystal ratio is lower than that of the first light guide layer, the interface resistance between the second light guide layer and the stripe region can be easily lowered, and the second light guide layer is the active layer. Since it is transparent to the laser light oscillated by, the heat generation in the vicinity of the active layer is suppressed.

Therefore, it is possible to achieve a high output and a long life of the semiconductor laser having a low operating current, a low astigmatic difference and a low noise.

According to the method of manufacturing a GaAlAs-based semiconductor laser device of the tenth aspect of the present invention, the current blocking layer formed on the first conductivity type optical guide layer is formed into a discontinuous stripe shape in the cavity direction. After the removal, the first conductivity type region is formed in the region of the light guide layer where the current block layer is removed, and thus a stripe region discontinuous in the cavity direction may be formed on the light guide layer. Because you can
It is possible to discontinuously and selectively inject current into the active layer in the cavity direction and to form a saturable absorption region below the stripe region in the active layer selectively in the cavity direction.

The stripe-shaped GaAlAs layer formed on the light guide layer has a refractive index of GaA of the current block layer.
Since the refractive index is higher than that of the 1As layer, an effective refractive index difference is formed inside and outside the stripe region, so that a refractive index guiding mechanism can be obtained.

According to the method of manufacturing a GaAlAs-based semiconductor laser device of the eleventh aspect of the present invention, the current block layer formed on the second optical guide layer of the first conductivity type has stripes discontinuous in the cavity direction. Stripes, the stripes discontinuous with respect to the cavity direction are formed on the second optical guide layer in order to form a first conductivity type area in the area of the second optical guide layer where the current blocking layer is removed. Since the region can be formed, a current can be selectively and discontinuously injected into the active layer in the cavity direction, and the saturable absorption region is selectively formed in the cavity direction below the stripe region in the active layer. Can be formed.

Further, since the AlAs mixed crystal ratio of the second light guide layer is set to be lower than the AlAs mixed crystal ratio of the first light guide layer, the interface resistance between the second light guide layer and the stripe region is easy. Since the second light guide layer is transparent to the laser light oscillated by the active layer, heat generation in the vicinity of the active layer is suppressed.

The stripe-shaped GaAlAs layer formed on the second optical guide layer has a refractive index of G of the current block layer.
Since the refractive index is higher than that of the aAlAs layer, an effective refractive index difference is formed inside and outside the stripe region, so that a refractive index guiding mechanism can be obtained.

According to the method of manufacturing an InGaAlP-based semiconductor laser device according to the twelfth aspect of the present invention, the current block layer formed on the first conductivity type optical guide layer is formed into a discontinuous stripe shape in the cavity direction. After the removal, the first conductivity type region is formed in the region of the light guide layer where the current block layer is removed, and thus a stripe region discontinuous in the cavity direction may be formed on the light guide layer. Therefore, the current can be selectively and discontinuously injected into the active layer in the cavity direction, and the saturable absorption region can be selectively formed in the cavity direction below the stripe region in the active layer. . Further, since the refractive index of the stripe-shaped InGaAlP layer formed on the optical guide layer is higher than that of the InGaAlP layer of the current blocking layer, an effective refractive index difference is formed inside and outside the stripe region, so that the refractive index guiding is performed. The mechanism is obtained.

According to the method of manufacturing an InGaAlP-based semiconductor laser device of the thirteenth aspect, the current block layer formed on the second optical guide layer of the first conductivity type has stripes discontinuous in the cavity direction. And then removing the first light guide layer in the region where the current blocking layer is removed in the second light guide layer.
Since the conductive type region is formed, a stripe region which is discontinuous in the cavity direction can be formed on the second optical guide layer, and therefore, it is discontinuous in the cavity direction with respect to the active layer and selected. It is possible to selectively inject current and to form a saturable absorption region selectively in the resonator direction below the stripe region in the active layer.

The Al mixed crystal ratio of the second optical guide layer is set to the first
Since it is lower than the Al mixed crystal ratio of the light guide layer,
The interface resistance between the light guide layer and the stripe region can be easily reduced, and since the second light guide layer is transparent to the laser light oscillated by the active layer, heat generation in the vicinity of the active layer is suppressed. It

Since the refractive index of the stripe-shaped InGaAlP layer formed on the second optical guide layer is higher than that of the InGaAlP layer of the current block layer, an effective refractive index difference is formed inside and outside the stripe region. , A refractive index guiding mechanism is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the optical characteristics of the semiconductor laser device according to the first embodiment during laser oscillation, the effective refractive index difference inside and outside the stripe region, and the structural parameter.

FIG. 3 is a diagram showing each step of the method of manufacturing the semiconductor laser device according to the first embodiment.

FIG. 4 is a diagram showing current-light output characteristics of the semiconductor laser device according to the first embodiment.

FIG. 5 is a diagram showing a light output dependency of a horizontal divergence angle of the semiconductor laser device according to the first embodiment.

FIG. 6 is a diagram showing the optical output dependence of the astigmatic difference of the semiconductor laser device according to the first embodiment.

FIG. 7 is a diagram showing current-light output characteristics of the semiconductor laser device according to the second embodiment of the present invention.

FIG. 8 is a sectional view of a semiconductor laser device according to a third embodiment of the present invention.

FIG. 9 is a diagram showing the relationship between the optical characteristics of the semiconductor laser device according to the third embodiment during laser oscillation, the effective refractive index difference between the inside and outside of the stripe region, and the structural parameter.

FIG. 10 is a diagram showing each step of the method for manufacturing the semiconductor laser device according to the third embodiment.

FIG. 11 is a diagram showing current-light output characteristics of the semiconductor laser device according to the third embodiment.

FIG. 12 is a diagram showing the optical output dependence of the horizontal divergence angle of the semiconductor laser device according to the third embodiment.

FIG. 13 is a diagram showing the optical output dependence of the astigmatic difference of the semiconductor laser device according to the third embodiment.

FIG. 14 is a diagram showing current-light output characteristics of a semiconductor laser device according to a fourth embodiment of the present invention.

FIG. 15 is a sectional view of a conventional semiconductor laser device.

[Explanation of symbols]

 1 Semiconductor Substrate 2 Buffer Layer 3 First Cladding Layer 4 Active Layer 5 First Optical Guide Layer 6 Second Optical Guide Layer 7 Current Blocking Layer 7a Stripe Region 8 Second Cladding Layer 9 Contact Layer 11 Semiconductor Substrate 12 First Cladding Layer 13 Active layer 14 First light guide layer 15 Second light guide layer 16 Current blocking layer 16a Stripe region 17 Second clad layer 18 Contact layer 21 Semiconductor substrate 22 Buffer layer 23 First clad layer 24 Active layer 25 First light guide layer 26 Second light guide layer 27 Current blocking layer 27a Stripe region 28 Protective layer 29 Second clad layer 30 Contact layer

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akio Yoshikawa 1-1, Sachimachi Takatsuki City, Osaka Prefecture Matsushita Electronics Industrial Co., Ltd. (72) Inventor Hiroki Naito 1-1, Sachimachi Takatsuki City, Osaka Matsushita Electronics Industry Within the corporation

Claims (13)

[Claims] 1. An active layer made of a semiconductor layer, a light guide layer made of a semiconductor layer of a first conductivity type formed on the active layer, and a first conductivity type formed on the light guide layer. In the semiconductor laser device, the stripe region is formed of a semiconductor layer, and the second conductivity type current blocking layer is formed on both sides of the stripe region on the light guide layer. A semiconductor laser device having at least one discontinuous portion. 2. An active layer composed of a Ga _1-x Al _x As layer, and a Ga _{1 -Y 1} A of the first conductivity type formed on the active layer.
a light guide layer composed of l _Y1 As layer, a stripe region made of the first conductivity type Ga _1-Y2 Al _Y2 As layer formed on the light guide layer, the stripe region in on the optical guide layer Conductivity type Ga ₁ -Z formed on both sides of the
In a semiconductor laser device including a current block layer made of an Al _Z As layer, X, Y1, Y of respective mixed crystal ratios of the active layer, the light guide layer, the stripe region and the current block layer are provided.
The relationship of Z>Y2> X ≧ 0 and Y1> X is established between 2 and Z, and the stripe region has at least one discontinuity in the cavity direction. Semiconductor laser device. 3. An active layer having a quantum well structure, an optical guide layer made of a Ga _{1 -Y 1} Al _{Y 1} As layer of the first conductivity type formed on the active layer, and an optical guide layer on the optical guide layer. The formed stripe region of the first conductivity type Ga _{1 -Y 2} Al _{Y 2} As layer and the second conductivity type Ga _{1 -Z} Al _Z As formed on both sides of the stripe region on the light guide layer.
In a semiconductor laser device including a current block layer, the relationship of Y1> 0 and Z>Y2> 0 between Y1, Y2, and Z of the mixed crystal ratios of the optical guide layer, the stripe region, and the current block layer. The semiconductor laser device is characterized in that the stripe region has at least one discontinuous portion in the cavity direction. 4. An active layer composed of a Ga _1-x Al _x As layer and a Ga _{1 -Y 1} A of the first conductivity type formed on the active layer.
a first light guide layer made of a _{Y 1} As layer, a second light guide layer made of a first conductivity type Ga _{1 -Y 2} Al _{Y 2} As formed on the first light guide layer, and a second light guide layer. A stripe region formed of a Ga _{1 -Y 3} Al _{Y 3} As layer of the first conductivity type formed on the guide layer, and a stripe region of the second conductivity type formed on both sides of the stripe region on the second optical guide layer. Ga _1-Z
In a semiconductor laser device including a current block layer made of an Al _Z As layer, X, Y1 of respective mixed crystal ratios of the active layer, the first light guide layer, the second light guide layer, the stripe region and the current block layer, Z>Y3> between Y2, Y3 and Z
The semiconductor laser device is characterized in that the relations of Y2> X ≧ 0 and Y1> Y2 are established, and the stripe region has at least one discontinuous portion in the cavity direction. 5. An active layer having a quantum well structure, a first light guide layer made of a Ga _{1 -Y 1} Al _{Y 1} As layer of a first conductivity type formed on the active layer, and the first light guide. A second optical guide layer formed of a Ga _{1 -Y 2} Al _{Y 2} As layer of the first conductivity type formed on the layer, and a Ga _{1 -Y 3} of the first conductivity type formed on the second light guide layer. A stripe region made of an Al _Y3 As layer and a second conductivity type Ga _{1 -Z} Al _Z A formed on both sides of the stripe region on the second light guide layer.
In the semiconductor laser device including a current block layer made of s, Y of each mixed crystal ratio of the active layer, the first light guide layer, the second light guide layer, the stripe region, and the current block layer.
Z>Y3>Y2> 0 and Y between 1, Y2, Y3 and Z
The semiconductor laser device is characterized in that the relation of 1> Y2 is established, and the stripe region has at least one discontinuous portion in the cavity direction. 6. An active layer comprising an In _0.5 (Ga _1-X Al _X ) _0.5 P layer, and a first conductivity type In _0.5 (Ga _{1 -Y1} Al _Y1 ) _0.5 P layer formed on the active layer. And a first conductivity type I formed on the light guide layer.
n _0.5 (Ga _{1 -Y 2} Al _{Y 2} ) _0.5 P layer stripe region, and second conductivity type In _0.5 (Ga _{1 -Z} ) formed on both sides of the stripe region on the light guide layer.
In a semiconductor laser device including a current block layer made of Al _Z ) _0.5 P layer, X, Y of each mixed crystal ratio of the active layer, the light guide layer, the stripe region and the current block layer.
The relationship of Z> Y2 ≧ X ≧ 0 and Y1> X is established between 1, Y2 and Z, and the stripe region has at least one discontinuous portion in the resonator direction. Characteristic semiconductor laser device. 7. An active layer having a quantum well structure, and a first conductivity type In _0.5 (Ga _{1 -Y1} A) formed on the active layer.
l _{Y1) 0.5} and the light guide layer composed of P layer, an In _0.5 the first conductivity type formed on the light guide layer (Ga _1-Y2 A
current block composed of a stripe region formed of a layer of _{Y 2} ) _0.5 P and a second conductivity type In _0.5 (Ga _{1 -Z} Al _Z ) _0.5 P layer formed on both sides of the stripe region on the light guide layer. In the semiconductor laser device including a layer, Z> Y2 ≧ 0 between Y1, Y2, and Z of the mixed crystal ratios of the light guide layer, the stripe region, and the current block layer.
And Y1 ≧ 0, and the stripe region has at least one discontinuity in the cavity direction. 8. An active layer composed of an In _0.5 (Ga _1-X Al _X ) _0.5 P layer, and a first conductivity type In _0.5 (Ga _1-Y1 Al _Y1 ) _0.5 P layer formed on the active layer. a first optical guide layer composed of a layer, a first conductivity type _{in 0. 5 (Ga 1-Y2} Al Y2) formed on the first optical guide layer and the second light guide layer composed of _0.5 P layer A stripe region of a first conductivity type In _0.5 (Ga _{1 -Y 3} Al _{Y 3} ) _0.5 P layer formed on the second light guide layer, and a stripe region of the stripe region on the second light guide layer. Second conductivity type I formed on both sides
A semiconductor laser device comprising a current blocking layer made of an n _0.5 (Ga _{1 -Z} Al _Z ) _0.5 P layer, the active layer, the first optical guide layer, the second optical guide layer, the stripe region and the current block. X, Y1, Y of each mixed crystal ratio of the layer
2, Y3 and Z between Z>Y3> Y2 ≧ X ≧ 0 and Y1
The semiconductor laser device is characterized in that the relation of> Y2 is established, and the stripe region has at least one discontinuous portion in the cavity direction. 9. An active layer having a quantum well structure and a first conductivity type In _0.5 (Ga _{1 -Y1} A) formed on the active layer.
and a first conductivity type In _0.5 (Ga) formed on the first light guide layer, and the first light guide layer is formed of a 1 _{Y 1} ) _0.5 P layer.
_1-Y2 Al _Y2 ) _0.5 P second light guide layer, and a first conductivity type In formed on the second light guide layer
_0.5 (Ga _{1 -Y 3} Al _{Y 3} ) _0.5 P layer stripe region and the second conductivity type In _0.5 (Ga) formed on both sides of the stripe region on the second optical guide layer.
_1-Z Al _Z ) _0.5 P current blocking layer comprising a semiconductor laser device, the first optical guide layer, the second optical guide layer, the stripe region and the current blocking layer Y1 of each mixed crystal ratio, Z>Y3> Y2 between Y2, Y3 and Z
The semiconductor laser device is characterized in that the relations ≧ 0 and Y1> Y2 are established, and the stripe region has at least one discontinuous portion in the cavity direction. 10. An active layer made of a semiconductor layer and a first conductivity type Ga are formed on a semiconductor substrate by an epitaxial growth method.
_1-Y1 Al _Y1 As layer a light guide layer, and Ga _1-Z Al Z As layer current blocking layer made of the second conductivity type formed of said Ga _1-Y1 Al _Y1 As layer and Ga _1-Z Al Z As A step of sequentially forming so that the relations of Y1> 0 and Z> 0 are established in each mixed crystal ratio of the layers; and by selectively etching the current block layer, at least the current block layer is formed. A step of removing one non-removed portion so as to expose the light guide layer in a stripe shape extending in the cavity direction; and a stripe shape in which the current block layer on the light guide layer is removed. In the region, a Ga _{1 -Y 2} Al _{Y 2} As layer of the first conductivity type is formed on the region by an epitaxial growth method.
_And a step of forming a _1-Z Al _Z As layer and a Ga _1-Y2 Al _Y2 As layer so that a relation of Z>Y2> 0 is established between respective mixed crystal ratios. Laser device manufacturing method. 11. An active layer made of a semiconductor layer and a first conductivity type Ga are formed on a semiconductor substrate by an epitaxial growth method.
_{From a first} optical guide layer made of a _1-Y1 Al _Y1 As layer, a second optical guide layer made of a first conductivity type Ga _{1 -Y2} Al _Y2 As layer and a second conductivity type Ga _1-Z Al _Z As layer The Ga _{1 -Y 1} Al _{Y 1} As layer and the Ga _{1 -Y 2} Al _{Y 2} As layer.
Z> Y2 between the mixed crystal ratios of the layer and the Ga _1-Z Al _Z As layer.
>Y1> 0, and by selectively etching the current blocking layer, at least one non-removed portion remains in the current blocking layer and A step of removing the second light guide layer in a stripe shape extending in the cavity direction so as to be exposed; and a region of the second light guide layer in which the current block layer is removed in a stripe shape, by an epitaxial growth method. the Ga _1-Y3 Al _Y3 as layer of the first conductivity type, the Ga _1-Z Al _Z as layer and Ga _1-Y3 Al _Y3 as layer Z between each mixing ratio of> so that Y3 relationship is established And a step of forming the semiconductor laser device. 12. An active layer made of a semiconductor layer and In of a first conductivity type are formed on a semiconductor substrate by an epitaxial growth method.
_An optical guide layer made of a _0.5 (Ga _{1 -Y 1} Al _{Y 1} ) _0.5 P layer and a current blocking layer made of a second conductivity type In _0.5 (Ga _{1 -Z} Al _Z ) _0.5 P layer are added to the In _0.5 (Ga _{1- Y1} Al
_{Forming a Y1} ) _0.5 P layer and an In _0.5 (Ga _{1 -Z} Al _Z ) _0.5 P layer so that the respective mixed crystal ratios satisfy Y1> 0 and Z>0; Selectively removing the current block by stripes extending in the cavity direction so that at least one non-removed portion remains and the light guide layer is exposed. A first conductivity type In _0.5 (Ga _{1 -Y 2} Al _{Y 2} ) _0.5 P layer was formed on the guide layer on the striped region from which the current blocking layer was removed by an epitaxial growth method.
The In _0.5 (Ga _{1 -Z} Al _Z ) _0.5 P layer and the I layer.
n _0.5 (Ga _{1 -Y 2} Al _{Y 2} ) _0.5 P between the mixed crystal ratios in the P layer
And a step of forming so as to satisfy the relation of> Y2 ≧ 0. 13. An active layer made of a semiconductor layer and In of a first conductivity type are formed on a semiconductor substrate by an epitaxial growth method.
_0.5 (Ga _{1 -Y 1} Al _{Y 1} ) _0.5 P-type first optical guide layer, first conductivity type In _0.5 (Ga _{1-Y 2} Al _{Y 2} ) _0.5 P-type second optical guide layer and second conductivity type In _0.5 (G
a _1-Z Al _Z ) _0.5 P layer, the In _0.5 (Ga _{1-Y 1} Al _{Y 1} ) _0.5 P layer, In _0.5 (G
a _{1-Y 2} Al _{Y 2} ) _0.5 P layer and In _0.5 (Ga _1-Z A
l _Z ) _0.5 P between the mixed crystal ratios of the P layer, Z> Y2 ≧ 0 and Y1
A step of forming so that the relation of> Y2 is established, and by selectively etching the current blocking layer, at least one non-removed portion remains in the current blocking layer and the second blocking layer is formed. A step of removing the light guide layer in a stripe shape so as to be exposed so as to be exposed in the cavity direction; and a first area formed on the second light guide layer in a stripe shape area where the current block layer is removed by an epitaxial growth method. Conductive type In _0.5 (Ga _1-Y3 Al _Y3 )
The _0.5 P layer, the _{In 0.5 (Ga 1-Z Al} Z) 0.5 P layer and _{In 0.5 (Ga 1-Y3 Al} Y3) 0.5 Z between each mixed crystal ratio of P layer> to Y3 relationship is established And a step of forming the semiconductor laser device.