JPH11214792A - Semiconductor laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser which is improved in design latitude, capable of controlling a waveguide mechanism lowered in power consumption, improved in output power, and lessened in astigmatism when it is of self-oscill type. SOLUTION: An n-type Alx1 Ga1-x1 As clad layer 2, and Alx2 Ga1-x2 As active layer 3, and p-type Alx1 Ga1-x1 As clad layer 4 are successively laminated on an n-type GaAs substrate 1. An n-type Alx1 Ga1-x1 As current constriction layer 5 and an n-type Alx3 Ga1-x3 As optical waveguide layer 6 which are each provided with stripe-like openings 5a and 6a that are formed at corresponding parts extending in a certain direction are formed on the p-type Alx1 Ga1-x1 As clad layer 4, where a lateral mode is controlled by the n-type Alx3 Ga1-x3 As optical waveguide layer 6. As an example, a waveguide mechanism is controlled corresponding to the composition of the n-type Alx3 Ga1-x3 As optical waveguide layer 6. In another example, the opening 5a is set smaller in width than the opening 5b to realize a self-oscill type semiconductor laser.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor laser, and more particularly, to a semiconductor laser using a III-V compound semiconductor.

[0002]

2. Description of the Related Art FIG. 6 is a sectional view of a conventional AlGaAs semiconductor laser. This conventional AlGaAs semiconductor laser has a SAN (Self Aligned Narrow stripe) structure.

As shown in FIG. 6, this conventional AlGaAs
In an s-based semiconductor laser, an n-type GaAs substrate 101
An n-type Al _x1 Ga _1-x1 As clad layer 102, an undoped Al _x2 Ga _1-x2 As active layer 103, a p-type Al _x1
Ga _1-x1 As clad layers 104 are sequentially stacked.

A p-type Al _x1 Ga _1-x1 As cladding layer 104
Above is a striped opening 1 of a predetermined width extending in one direction.
An n-type GaAs current confinement layer 105 having a layer 05a is provided. On the p-type Al _x1 Ga _1-x1 As clad layer 104 at the portion of the n-type GaAs current confinement layer 105 and the opening 105a, a p-type Al _x1 Ga _1-x1 As clad layer 106 is laminated. This p-type Al _x1 Ga _1-x1 A
On the s cladding layer 106, a p-type GaAs cap layer 10
7 are provided.

[0005] On the p-type GaAs cap layer 107, a p-type electrode 108 such as a Ti / Pt / Au electrode is provided, while on the back surface of the n-type GaAs substrate 101, for example, an AuGe / Ni electrode. An n-side electrode 109 is provided.

Here, _x1 in the n-type Al _x1 Ga _1-x1 As clad layer 102, p-type Al _x1 Ga _1-x1 As clad layer 104 and p-type Al _x1 Ga _1-x1 As clad layer 106, and Al _x2 X _{2 in the} Ga _{1 -x 2} As active layer 103
Satisfies the relationship 0 ≦ x2 <x1 ≦ 1. Also, _x2 in the Al _x2 Ga _1-x2 As active layer 103 is:
Preferably, it is selected so as to satisfy 0.1 ≦ x2 ≦ 0.25. Here, as an example of x1 and x2, x1 = 0.47 and x2 = 0.13, respectively.

Next, a method of manufacturing the conventional AlGaAs semiconductor laser will be described.

First, as shown in FIG. 7, an n-type Al _x1 Ga _1-x1 As clad layer 10 is formed on an n-type GaAs substrate 101.
2, Al _x2 Ga _1-x2 As active layer 103, p-type Al _x1 Ga
_{The 1-x1} As cladding layer 104 and the n-type GaAs current confinement layer 105 are formed by metal organic chemical vapor deposition (MOCV, for example).
It grows sequentially by the method D).

Next, on the n-type GaAs current confinement layer 105, a mask (not shown) having a stripe-shaped opening having a predetermined width and extending in one direction and made of a SiO ₂ film, a SiN _x film or the like is formed. Next, using this mask as an etching mask, the n-type GaAs current confinement layer 105 is selectively etched by a wet etching method or a dry etching method. As a result, as shown in FIG. 8, a stripe-shaped opening 105a extending in one direction is formed in the n-type GaAs current confinement layer 105. Thereafter, the mask used for the etching is removed.

[0010] Next, as shown in FIG. 9, the opening 105 of the n-type GaAs current confinement layer 105 is buried so that n
P-type Al _x1 Ga
_{The 1-x1} As cladding layer 106 is sequentially grown by, for example, the MOCVD method, and the p-type GaAs cap layer 107 is grown on the entire surface of the p _- type Al _x1 Ga _1-x1 As cladding layer 106 by, for example, the MOCVD method.

Next, a p-side electrode 108 is formed on the p-type GaAs cap layer 107, and an n-side electrode 109 is formed on the back surface of the n-type GaAs substrate 101. As described above, the intended AlGaAs-based semiconductor laser is manufactured.

[0012]

However, in the conventional AlGaAs semiconductor laser configured as described above, the n-type GaAs current confinement layer 105 is perpendicular to the cavity length direction and parallel to the junction plane. Since the n-type GaAs current confinement layer 105 controls the lateral mode, it also serves as an optical waveguide layer for controlling the optical waveguide in a direction (hereinafter, this direction is referred to as a lateral direction). .

That is, when the semiconductor laser is applied to a recording and / or reproducing apparatus such as an optical disk or a magneto-optical disk, the semiconductor laser is used as one of measures for reducing noise such as reducing return optical noise. There is a method of exciting oscillation. In order for the semiconductor laser to self-oscillate in this manner, the refractive index difference Δn for confining the transverse mode must be 5
By weakening lateral light confinement to about × 10 ^-3, the width of the optical waveguide region is made larger than the width of the carrier injection region in the active layer, and saturable absorbers are formed on both sides of the carrier injection region. This is very important.

However, the n-type GaAs current confinement layer 1
In the above-mentioned conventional AlGaAs-based semiconductor laser 05 also serving as an optical waveguide layer, the thickness of the p-type Al _x1 Ga _1-x1 As cladding layer 104 is controlled so that the n-type GaAs current confinement layer 105 is formed of Al _x2 Ga 0.5-from the _1-x2 As active layer 103
The self-pulsation type semiconductor laser can be realized only by separating the refractive index difference Δn for confining the transverse mode by about 1.0 μm to about 5 × 10 ^−3. There are limitations when designing semiconductor lasers.

As described above, the n-type GaAs current confinement layer 105 is _separated from the Al _x2 Ga _1-x2 As active layer 103 by 0.5
When the laser beam is separated by about 1.0 μm, the position of the beam waist of the laser beam in the lateral direction can be seen within the element about 20 μm from the end face of the resonator. There is a problem that it is difficult to manufacture a product satisfying the required specifications.

Further, in this conventional AlGaAs-based semiconductor laser, it is difficult to reduce power consumption and increase output because the loss of light due to the n-type GaAs current confinement layer 105 is large.

Accordingly, it is an object of the present invention to improve the degree of freedom of design, thereby controlling the waveguide mechanism, reducing power consumption and increasing output, and furthermore, self-excitation. An object of the present invention is to provide a semiconductor laser capable of reducing astigmatism when it is of an oscillation type.

[0018]

In order to achieve the above object, a semiconductor laser according to the present invention comprises a first laser of a first conductivity type.
, An active layer on the first clad layer, and a second conductive type second clad layer on the active layer, and stripe-shaped portions corresponding to each other on the second clad layer. A semiconductor layer including a current confinement layer of the first conductivity type having an opening of a first conductivity type and an optical waveguide layer is provided in a stacked manner, and a second conductivity type of the second conductivity type is formed on the second cladding layer in the opening portion of the semiconductor layer. A third cladding layer is provided, and the transverse mode is controlled by the optical waveguide layer.

In the present invention, the current confinement layer and the optical waveguide layer may be laminated in any order, for example, the current confinement layer and the optical waveguide layer may be laminated on the second clad layer in this order. An optical waveguide layer and a current confinement layer may be laminated in this order on the second clad layer. The conductivity type of the optical waveguide layer is the first.
Any of the conductivity type, the second conductivity type, or the intrinsic type may be used. Further, the width of the opening in the current confinement layer and the width of the opening in the optical waveguide layer can be independently controlled, and the thickness of the current confinement layer and the thickness of the optical waveguide layer can also be independently controlled.

In the present invention, the current confinement layer is typically formed of the second cladding from the viewpoint of not contributing to the control of the transverse mode and from the viewpoint of not absorbing light from the active layer. It is made of a material having the same composition as the layer.

According to the semiconductor laser of the present invention configured as described above, the first conductive type current confinement layer having the openings at the corresponding portions and the optical waveguide layer are provided on the second cladding layer. Since the semiconductor layer is provided and the transverse mode is controlled by the optical waveguide layer, the composition of the current confinement layer and the composition of the optical waveguide layer can be selected as necessary. The degree of freedom in design can be improved as compared with a conventional semiconductor laser also serving as a layer.

By improving the degree of freedom in designing a semiconductor laser, for example, Al _x1 Ga _{1 -x1}
A first cladding layer and a second cladding layer made of As, and an active layer made of Al _x2 Ga _1-x2 As (where 0 ≦
x2 <x1 ≦ 1), the current confinement layer is made of Al _x1 Ga _1-x1 As having the same composition as that of the second cladding layer, so that light loss in the current confinement layer is achieved. , Power consumption and output of the semiconductor laser can be reduced, and the optical waveguide layer is made of Al _x3 Ga _1-x3 As (where 0 ≦ x3 ≦ 1). Thereby, the waveguide mechanism of the semiconductor laser can be controlled. Specifically, the waveguide mechanism of this semiconductor laser is controlled such that _x3 in Al _x3 Ga _1-x3 As constituting the optical waveguide layer is 0 ≦ x3 ≦ x2
In the case of the above, a loss guided type absorbing light from the active layer, x2 <x
When 3 <x1, a refractive index anti-guided type (self-excited oscillation type) that does not absorb light from the active layer can be used, and when x1 <x3 ≦ 1, a real refractive index guided type can be used.

Also, for example, (Al _x1 Ga _1-x1 ) _1-y I
a first cladding layer and a second cladding layer made of n _y P, and an active layer made of (Al _x2 Ga _1-x2 ) _1-y In _y P (where 0 ≦ x2 <x1 ≦ 1, 0 ≦ y ≦ 1), the current confinement layer has the same composition as the second cladding layer (Al _x1 Ga _1-x1 ).
_{By using 1-y} In _y P, the loss of light from the active layer can be suppressed, whereby the power consumption and output of the semiconductor laser can be reduced. (Al _x3 Ga _1-x3 ) _1-y In _y P (where 0 ≦ x3 ≦ 1) makes it possible to control the waveguide mechanism of the semiconductor laser. _X3 in (Al _x3 Ga _1-x3 ) _1-y In _y P constituting the optical waveguide layer is 0.
When ≦ x3 ≦ x2, a loss-guided type that absorbs light from the active layer, when x2 <x3 <x1, a refractive index anti-guided type (self-excited oscillation type) that does not absorb light from the active layer, x1 <x3 When ≦ 1, it can be a real refractive index waveguide type.

Further, in this semiconductor laser, the width of the opening in the current confinement layer and the width of the opening in the optical waveguide layer can be controlled independently, and the width of the opening in the current confinement layer is made smaller than the width of the opening in the optical waveguide layer. When the width is reduced, the width of the optical waveguide region becomes larger than the width of the carrier injection region in the active layer, and the portions on both sides of the carrier injection region act as saturable absorbers, so that the semiconductor laser oscillates self-excited. For this reason, the semiconductor laser can be of a self-pulsation type without separating the current confinement layer from the active layer as in a conventional semiconductor laser in which the current confinement layer also serves as an optical waveguide layer. A small self-excited oscillation type semiconductor laser can be obtained.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the embodiments, the same or corresponding portions are denoted by the same reference numerals.

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

As shown in FIG. 1, in this AlGaAs semiconductor laser, an n-type Al _x1 Ga _1-x1 As clad layer 2 and an Al _x2 Ga _1-x2 As
An active layer 3 and a p-type Al _x1 Ga _1-x1 As clad layer 4 are sequentially stacked.

[0028] p-type on the AlGaAs cladding layer 4, n-type Al _x1 Ga having a stripe-shaped opening 5a and the opening 6a of a predetermined width extending in one direction in a portion corresponding to each other
_{A 1-x1} As current confinement layer 5 and an n-type Al _x3 Ga _1-x3 As optical waveguide layer 6 are sequentially laminated. Here, n-type Al _x3 G
The a _1-x3 As optical waveguide layer 6 is for controlling the transverse mode. In this AlGaAs-based semiconductor laser, the _x3 in the n-type Al _x3 Ga _1-x3 As optical waveguide layer 6 will be described later. It is possible to control the waveguide mechanism according to the value of. The n-type Al _x1 Ga _1-x1 As current confinement layer 5
Is made of a material having the same composition as the p-type Al _x1 Ga _1-x1 As cladding layer 4 and does not contribute to the control of the transverse mode.

The width of the opening in the n-type Al _x1 Ga _1-x1 As current confinement layer 5 and the width of the opening in the n-type Al _x3 Ga _1-x3 As optical waveguide layer 6 can be controlled independently.
In this case, the width of the opening 5a and the width of the opening 6a are substantially equal to each other. Also, n-type Al _x1 G
a _1-x1 As Thickness of As Current Constriction Layer 5 and n-type Al _x3 Ga
The thickness of the _1-x3 As optical waveguide layer 6 can also be independently controlled.
In this case, the thickness of the n-type Al _x1 Ga _1-x1 As current confinement layer 5 is 1 / th of the thickness of the n-type GaAs current confinement layer 105 also serving as the optical waveguide layer in the conventional AlGaAs-based semiconductor laser.
It can be 10 or less.

On the p-type Al _x1 Ga _1-x1 As cladding layer 4 at the opening 5a of the n-type Al _x3 Ga _1-x3 As optical waveguide layer 6 and the n-type Al _x1 Ga _1-x1 As current confinement layer 5 _Has a p-type Al _x1 Ga _1-x1 As clad layer 7 laminated thereon. On the p-type Al _x1 Ga _1-x1 As clad layer 7, a p-type GaAs cap layer 8 is provided.

A p-side electrode 9 such as a Ti / Pt / Au electrode is provided on the p-type GaAs cap layer 8. On the other hand, on the back surface of the n-type GaAs substrate 1, for example, I
An n-side electrode 10 such as an n-electrode is provided.

Here, the n-type Al _x1 Ga _1-x1 As clad layer 2, the p-type Al _x1 Ga _1-x1 As clad layer 4, the n-type Al
_x1 Ga _1-x1 As current confinement layer 5 and p-type Al _x1 Ga _1-x1
X1 in the As cladding layer 7 and Al _x2 Ga _1-x2 As
X2 in the active layer 3 satisfies the relationship of 0 ≦ x2 <x1 ≦ 1. Further, _x2 in the Al _x2 Ga _1-x2 As active layer 3 is preferably, for example, 0.1 ≦ x2 ≦ 0.25
Are chosen to satisfy Here, as an example of these x1 and x2, x1 = 0.4, respectively.
7, x2 = 0.13.

In this AlGaAs semiconductor laser, the waveguide mechanism may be controlled according to the value of x3 (0 ≦ x3 ≦ 1) in the n-type Al _x3 Ga _1-x3 As optical waveguide layer 6. It is possible. Specifically, this AlGa
The waveguide mechanism of an As-based semiconductor laser is an n-type Al _x3 Ga _1-x3
When x3 in the As optical waveguide layer 6 is 0 ≦ x3 ≦ x2,
Al _x2 Ga _{1 -x2} As is a loss-guided type absorbing light from the active layer 3, and when x2 <x3 <x1, Al _x2 Ga _1-x2
It becomes a refractive index anti-guiding type that does not absorb light from the As active layer 3, and becomes a real refractive index guiding type when x1 <x3 ≦ 1. When _x3 in the n-type _{Alx3Ga1 -x3As} optical waveguide layer 6 satisfies x2 <x3 <x1, the AlGaAs-based semiconductor laser oscillates by itself.

Here, an example of the thickness of each semiconductor layer constituting this AlGaAs semiconductor laser is given below.
The thickness of the l _x1 Ga _1-x1 As cladding layer 2 is, for example, about 2 μm, and the thickness of the Al _x2 Ga _1-x2 As active layer 3 is, for example, 10 n.
The thickness of the m, p-type Al _x1 Ga _1-x1 As cladding layer 4 is, for example, 0.2 to 0.5 μm, and the thickness of the n-type Al _x1 Ga _1-x1 As current confinement layer 5 is, for example, 0.05 to 0. .1 μm, n-type Al
The thickness of _x3 Ga _1-x3 As optical waveguide layer 6 is, for example 0.1~2μ
m. The n-type Al _x1 Ga _1-x1 As current confinement layer 5
The width of the opening 5a and the width of the opening 6a in the n-type Al _x3 Ga _1-x3 As optical waveguide layer 6 are, for example, 1 respectively.
６6 μm.

Next, the AlGa according to the first embodiment is
A method for manufacturing an As-based semiconductor laser will be described.

First, as shown in FIG. 2, an n-type Al _x1 Ga _1-x1 As clad layer 2
_x2 Ga1 _-x2 As active layer 3, p-type _Alx1 Ga1 _-x1 As cladding layer 4, n-type _Alx1 Ga1 _-x1 As current confinement layer 5, and n-type _Alx3 Ga1 _-x3 As optical waveguide layer 6. For example, MOCV
Grow sequentially by D method.

Next, the n-type Al _x3 Ga _1-x3 As optical waveguide layer 6
A mask (not shown) having a stripe-shaped opening having a predetermined width and extending in one direction and made of a SiO ₂ film, a SiN _x film, or the like is formed thereon. Next, using this mask as an etching mask, n-type A
l _x3 Ga _1-x3 As optical waveguide layer 6 and n-type Al _x1 Ga _1-x1
The As current confinement layer 5 is selectively etched. Thereby, as shown in FIG. 3, the n-type Al _x1 Ga _1-x1 As current confinement layer 5 and the n-type Al _x3 Ga _1-x3 As optical waveguide layer 6 have:
A stripe-shaped opening 5a and an opening 6a extending in one direction are formed, respectively. Thereafter, the mask used for the etching is removed.

Next, as shown in FIG. 4, n-type Al _x3 Ga
_The p-type Al _x1 Ga _1-x1 As clad layer 7 is grown by, for example, MOCVD so that the openings 5 a and 6 a are buried in the entire surface of the _1-x3 As optical waveguide layer 6.
A p-type GaAs cap layer 8 is grown on the entire surface of the l _x1 Ga _1-x1 As clad layer 7 by, for example, MOCVD.

Next, a p-side electrode 9 is formed on the p-type GaAs cap layer 8 by, for example, a vacuum deposition method or a sputtering method, and an n-side electrode 10 is formed on the back surface of the n-type GaAs substrate 1. As described above, the target AlGaAs
An s-based semiconductor laser is manufactured.

According to the AlGaAs-based semiconductor laser according to the first embodiment configured as described above, the n-type A
l _x1 Ga _1-x1 As current confinement layer 5 and n-type Al _x3 Ga _1-x3 A
s optical waveguide layer 6 is provided independently, and n-type Al _x3 Ga
_{Since the} transverse mode is controlled by the _1-x3 As optical waveguide layer 6, the waveguide mechanism can be changed to a loss waveguide type (0 ≦ 0) according to the composition of the n-type Al _x3 Ga _1-x3 As optical waveguide layer 6. x3 ≦ x
2), a self-oscillating refractive index anti-guided type (x2 <x3 <x
1) or a real refractive index waveguide type (x1 <x3 ≦ 1).

As a current confinement layer, Al _x2 Ga _{1 -x2}
Since the n-type Al _x1 Ga _1-x1 As current confinement layer 5 having a band gap larger than the band gap of the As active layer 3 is used, the n-type Al _x1 Ga _1-x1 As current confinement layer 5 and the n-type Al _In the portion of the x3Ga1 _-x3As optical waveguide layer 6, light loss due to the n-type _{Alx1Ga1 -x1As} current confinement layer 5 can be eliminated, so that the conventional current confinement layer also serves as the optical waveguide layer. Compared with a semiconductor laser, lower power consumption and higher output can be achieved.

Next, a second embodiment of the present invention will be described. FIG. 5 shows an AlGa according to the second embodiment.
FIG. 2 is a sectional view of an As-based self-pulsation type semiconductor laser.

As shown in FIG. 5, in this AlGaAs-based self-pulsation type semiconductor laser, an n-type Al _x1 Ga _1-x1
The width of the opening 5a in the As current confinement layer 5 is n-type Al _x3
The width is smaller than the width of the opening 6a in the Ga _1-x3 As optical waveguide layer 6. Further, the n-type Al _x3 Ga _1-x3 As optical waveguide layer 6
Is selected so that x1 ≦ x3 is satisfied, for example, and the effective refractive index difference Δn satisfies Δn ≦ 5 × 10 ⁻³ . The thickness of the p-type Al _x1 Ga _1-x1 As clad layer 4 is selected to be, for example, 0.2 to 0.3 μm. This Al
Other configurations of the GaAs self-excited oscillation type semiconductor laser are as follows.
Since this is the same as the AlGaAs semiconductor laser according to the first embodiment, the description is omitted.

In the AlGaAs-based self-excited oscillation semiconductor laser according to the second embodiment, Al _x2 Ga _1-x2 As
The width of the carrier injection region in the active layer 3 is n-type Al
The width of the optical waveguide region in the Al _x2 Ga _1-x2 As active layer 3 is determined by the width of the opening 5a of the _x1 Ga _1-x1 As current confinement layer 5 and the n-type Al _x3 Ga _1-x3 As optical waveguide layer 6 Opening 6a
Is determined by the width of In this case, n-type Al _x1 Ga _1-x1 As
The width of the opening 5a in the current confinement layer 5 is n-type _Alx3Ga.
Are narrower than the width of the opening 6a in the _1-x3 As optical guide layer 6, the width of the optical waveguide region in Al _x2 Ga _1-x2 As active layer 3 is larger than the width of the carrier injection region, on both sides of the carrier injection region The AlGaAs-based self-sustained pulsation type semiconductor laser oscillates by self-oscillation because the optical waveguide region in the portion acts as a saturable absorber.

In manufacturing the AlGaAs-based self-excited oscillation semiconductor laser according to the second embodiment, n-type GaAs
After growing the n-type Al _x3 Ga _1-x3 As optical guide layer 6 on s substrate 1, first, n-type Al _x3 Ga _1-x3 As optical using a mask having an opening of a predetermined width extending in one direction By selectively etching the wave layer 6, the n-type Al _x3 G
The opening 6a is formed in a _1-x3 As optical guide layer 6, then, the portion corresponding to the opening 6a of the n-type Al _x3 Ga _1-x3 As optical guide layer 6, a mask having a narrow opening from the opening 6a by selectively etching the n-type Al _x1 Ga _1-x1 as current confinement layer 5 is used to form an opening 5a in the n-type Al _x1 Ga _1-x1 as current confinement layer 5. The other points are the same as those of the method of manufacturing the AlGaAs semiconductor laser according to the first embodiment, and the description is omitted.

According to the second embodiment configured as described above, the width of the opening 5a in the n-type Al _x1 Ga _1-x1 As current confinement layer 5 is changed to the n-type Al _x3 Ga _1-x3 As optical waveguide. Layer 6
By making the width smaller than the width of the opening 6a, a self-pulsation type AlGaAs-based semiconductor laser can be realized. For this reason, as in the prior art, n-type Al _x3 Ga _1-x3 A
It is not necessary to separate the s optical waveguide layer 6 from the Al _x2 Ga _1-x2 As active layer 3 and, therefore, the thickness of the p-type Al _x1 Ga _1-x1 As clad layer 4 can be reduced, so that astigmatism is obtained. Can be reduced to, for example, about 5 μm. Further, this AlGaAs-based self-pulsation type semiconductor laser has a
Because of the thickness of the mold Al _x1 Ga _1-x1 As cladding layer 4 can be self-oscillating independently, depending on the thickness of the p-type Al _x1 Ga _1-x1 As cladding layer 4, the astigmatism magnitude Can also be controlled. Also, unlike the case where a conventional AlGaAs-based semiconductor laser is of a self-pulsation type, it does not require delicate control of the structure, and thus has an advantage that design and manufacture are easy.

As a current confinement layer, Al _x2 Ga _{1 -x2}
By using the n-type Al _x1 Ga _1-x1 As current confinement layer 5 having a band gap larger than the band gap of the As active layer 3, low power consumption and high power consumption can be achieved as in the first embodiment. Output can be achieved.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above embodiments, and various modifications based on the technical idea of the present invention are possible. For example, the numerical values, materials, structures, and the like described in the embodiments are merely examples, and the present invention is not limited thereto. Specifically, for example, the first
And n-type Al _x3 Ga _1-x3 As in the second embodiment
Instead of the optical waveguide layer 6, a p-type Al _x3 Ga _1-x3 As optical waveguide layer can be used.

[0049] Further, Okeite the first and second embodiments described above, p-type Al _x1 Ga on _1-x1 As cladding layer 4, n-type Al _x1 Ga _1-x1 As current blocking layer 5 and the n Type A
The l _x3 Ga _1-x3 As optical waveguide layer 6 is sequentially laminated. This is because the p-type Al _x1 Ga _1-x1 As cladding layer 4 is formed.
An n-type Al _x3 Ga _1-x3 As optical waveguide layer 6 and an n-type A
The l _x1 Ga _1-x1 As current confinement layer 5 may be sequentially stacked.

For example, in the first and second embodiments described above, the conductivity types of the semiconductor layers constituting the substrate and the semiconductor laser may be reversed.

In the first and second embodiments, the present invention is applied to a DH structure (Double Heterostructu).
re) was applied to an AlGaAs-based semiconductor laser, but the present invention relates to an SCH structure (Separate C).
The present invention can also be applied to an AlGaAs-based semiconductor laser having an onfinement heterostructure. Further, the active layer may have a multiple quantum well (MQW) structure.

Further, the present invention relates to the above-described AlGaAs.
The present invention can be applied to a semiconductor laser using another group III-V compound semiconductor such as an AlGaInP semiconductor laser in addition to the semiconductor laser.

[0053]

As described above, according to the present invention, the semiconductor layer including the first conductive type current confinement layer and the optical waveguide layer having openings in the corresponding portions on the second cladding layer. Is provided, and since the transverse mode is controlled by the optical waveguide layer, the composition of the current confinement layer and the composition of the optical waveguide layer can be selected as necessary. The degree of freedom in design can be improved as compared with a conventional semiconductor laser that also serves as a conventional semiconductor laser. And, in this way, by improving the degree of freedom of design, control of the waveguide mechanism, low power consumption and high output can be achieved,
Moreover, it is possible to realize a semiconductor laser that can reduce astigmatism when it is a self-pulsation type.

[Brief description of the drawings]

FIG. 1 shows an AlGaAs according to a first embodiment of the present invention.
It is sectional drawing of an s-system semiconductor laser.

FIG. 2 shows AlGaAs according to the first embodiment of the present invention.
FIG. 6 is a cross-sectional view for describing the method for manufacturing the s-based semiconductor laser.

FIG. 3 shows AlGaAs according to the first embodiment of the present invention.
FIG. 6 is a cross-sectional view for describing the method for manufacturing the s-based semiconductor laser.

FIG. 4 shows AlGaAs according to the first embodiment of the present invention.
FIG. 6 is a cross-sectional view for describing the method for manufacturing the s-based semiconductor laser.

FIG. 5 shows an AlGaAs according to a second embodiment of the present invention.
FIG. 3 is a cross-sectional view of an s-system self-excited oscillation type semiconductor laser.

FIG. 6 is a cross-sectional view of a conventional AlGaAs semiconductor laser.

FIG. 7 is a cross-sectional view for explaining a method for manufacturing a conventional AlGaAs-based semiconductor laser.

FIG. 8 is a cross-sectional view for explaining a method for manufacturing a conventional AlGaAs-based semiconductor laser.

FIG. 9 is a cross-sectional view illustrating a method for manufacturing a conventional AlGaAs-based semiconductor laser.

[Explanation of symbols]

1 ... n-type GaAs substrate, 2 ... n-type Al _x1 Ga
_1-x1 As clad layer, 3 ... Al _x2 Ga _1-x2 As active layer, 4,7 ... p-type Al _x1 Ga _1-x1 As clad layer,
5... N-type Al _x1 Ga _1-x1 As current confinement layer, 5a, 6
a: opening, 6: n-type Al _x3 Ga _1-x3 As optical waveguide layer, 8: p-type GaAs cap layer, 9: p-side electrode, 10: n-side electrode

Claims (9)

[Claims] 1. A first cladding layer of a first conductivity type, an active layer on the first cladding layer, and a second cladding layer of a second conductivity type on the active layer, On the second cladding layer, a semiconductor layer including a first-conduction-type current constriction layer having an opening in a portion corresponding to each other and an optical waveguide layer is provided, and the semiconductor layer in the opening portion of the semiconductor layer is provided. A semiconductor laser, wherein a third cladding layer of a second conductivity type is provided on a second cladding layer, and a lateral mode is controlled by the optical waveguide layer. 2. The semiconductor laser according to claim 1, wherein said current confinement layer is made of a material having the same composition as said second cladding layer. 3. The semiconductor laser according to claim 1, wherein a waveguide mechanism of said semiconductor laser is controlled according to a composition of said optical waveguide layer. 4. The semiconductor laser according to claim 1, wherein said semiconductor laser is a semiconductor laser using a group III-V compound semiconductor. 5. The semiconductor laser according to claim 1, wherein said Al _x1 Ga _1-x1 A
An AlGaAs-based semiconductor laser comprising the first cladding layer and the second cladding layer made of s, and the active layer made of Al _x2 Ga _1-x2 As (where 0 ≦ x2 <x1 ≦ 1). The current confinement layer is made of Al _x1 Ga _1-x1 As having the same composition as the second cladding layer, and the optical waveguide layer is made of Al _x3 Ga _1-x3 As (where 0 ≦
x3 ≦ 1), and Al _x3 G constituting the optical waveguide layer
2. The semiconductor laser according to claim 1, wherein the waveguide mechanism is controlled according to the value of x3 in a1 _-x3As . 6. The waveguide mechanism of the semiconductor laser, wherein _x3 in Al _x3 Ga _1-x3 As constituting the optical waveguide layer is 0.
When ≦ x3 ≦ x2, it becomes a loss guided type that absorbs light from the active layer, and when x2 <x3 <x1, it becomes a refractive index anti-guided type that does not absorb light from the active layer, and x1 <x3 ≦
6. The semiconductor laser according to claim 5, wherein the semiconductor laser is of a real refractive index waveguide type when the value is 1. 7. The semiconductor laser according to claim 1, wherein (Al _x1 G
a _1-x1 ) _1-y The first clad layer and the second clad layer made of In _y P, and (Al _x2 Ga _1-x2 ) _1-y
The active layer of In _y P (where 0 ≦ x2 <x1
≦ 1, 0 ≦ y ≦ 1), wherein the current confinement layer is made of (Al _x1 Ga _1-x1 ) _1-y In _y P having the same composition as the second cladding layer. At the same time, the optical waveguide layer is composed of (Al _x3 Ga _1-x3 ) _1-y In
x in (Al _x3 Ga _1-x3 ) _1-y In _y P which is composed of _y P (where 0 ≦ x3 ≦ 1) and constitutes the optical waveguide layer.
2. The semiconductor laser according to claim 1, wherein the waveguide mechanism is controlled according to the value of 3. 8. The waveguide mechanism of the semiconductor laser is such that when _x3 in (Al _x3 Ga _1-x3 ) _1-y In _y P constituting the optical waveguide layer is 0 ≦ x3 ≦ x2, the waveguide from the active layer is It becomes a loss guided type that absorbs light, and becomes a refractive index anti-guided type that does not absorb light from the active layer when x2 <x3 <x1,
8. The semiconductor laser according to claim 7, wherein the semiconductor laser is of a real refractive index waveguide type when x1 <x3≤1. 9. The semiconductor laser according to claim 1, wherein the width of the opening in the current confinement layer is smaller than the width of the opening in the optical waveguide layer. Semiconductor laser.