JP2001284708A - Semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an automatic oscillation type semiconductor laser device in two crystal growth processing steps. SOLUTION: An n-type AlGaInP clad layer 102, an active layer 103, a p-type first clad layer 104 made of a p-type (AlX1Ga1-X1)Z1In1-Z1P (0<=Y<=1 and 0<Z1<1), a current block layer 105 made of an n-type (AlYGa1-Y)Z2In1-Z2P (0<=Y<=1 and 0<Z2<1) having a striped region 105a, a p-type second clad layer 106 made of a p-type (AlX2Ga1-X2)Z3In1-Z3P (0<=X2<=1 and 0<Z3<1), and a p-type GaAs contact layer 107 are formed sequentially on an n-type GaAs substrate 101. In this case, there is a relation of Y>X1 and Y>X2 between aluminum compositions (X1, Y, and X2) included in the p-type first clad layer 104, the current block layer 105, and the p-type second clad layer 106. The excessive saturation absorbing region is formed just under the current block layer 105 in the active layer 103.

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, and more particularly to a self-excited oscillation type semiconductor laser device that emits red laser light.

[0002]

2. Description of the Related Art Red semiconductor lasers are widely used as light sources for DVD devices. In addition, the self-pulsation type semiconductor laser device does not require an external high-frequency superimposing circuit for reducing return light noise, and is therefore a key semiconductor device from the viewpoint of miniaturization and cost reduction.

A typical conventional structure of a self-pulsation type semiconductor laser device will be described below with reference to FIG.

FIG. 8 shows a cross-sectional structure of a conventional semiconductor laser device 10 in which an n-type GaAs substrate 11 has
N-type cladding layer 12 made of p-type AlGaInP layer, active layer 13 having a multiple quantum well structure, p-type AlGaInP
P-type first cladding layer 14 and saturable absorption layer 1
5, and a p-type second cladding layer 16 made of a p-type AlGaInP layer and having a ridge portion is sequentially formed. That is, the saturable absorption layer 15 is inserted between the p-type first cladding layer 14 and the p-type second cladding layer 16.

On the upper side of the p-type second cladding layer 16 and on both sides of the ridge portion, a current blocking layer 17 made of an n-type GaAs layer is formed, and the p-type second cladding layer 1 is formed.
A contact layer 18 is formed on the ridge portion 6 and between the current block layers 17, and a p-type GaAs is formed on the current block layer 17 and the contact layer 18.
A cap layer 19 made of a layer is formed.

On the lower surface of the n-type GaAs substrate 11, n
A mold electrode 20 is formed, and a p-type electrode 21 is formed on the upper surface of the cap layer 19.

In order to manufacture the conventional semiconductor laser device, an n-type cladding layer 12 is formed on an n-type GaAs substrate 11.
N-type AlGaInP layer, active layer 13, p-type AlGaInP layer as first cladding layer 14, saturable absorption layer 1
5. p-type AlGaIn to be the second p-type cladding layer 16
The P layer and the contact layer 18 were sequentially crystal-grown (1
After the second growth step, patterning is performed to etch the second cladding layer 16 and the contact layer 18 to form a ridge, and then the second cladding layer 16 on both sides of the ridge is formed.
After selectively crystal-growing an n-type GaAs layer serving as the current block layer 17 thereon (second growth step), a p-type GaAs layer serving as the cap layer 19 is formed on the contact layer 18 and the current block layer 17. A crystal is grown (third growth step).

The light distribution 22 of the laser light oscillated from the active layer 13 is confined in a region below the ridge portion in the active layer 13, but the saturable absorption layer 14 exists within the range where the light is distributed. Therefore, self-sustained pulsation can be realized.

FIG. 9 shows an optical output-current characteristic in a conventional semiconductor laser device, and curves a and a in FIG.
b, c, d, and e represent characteristics when the temperature of the semiconductor laser device is 20 ° C., 30 ° C., 40 ° C., 50 ° C., and 60 ° C., respectively. As can be seen from FIG. 9, the discontinuity of the characteristic accompanying the self-excited oscillation is seen near the threshold.
The operating current at the time of 5 mW light output at room temperature (25 ° C.) is 86.6 mA.

[0010]

However, in the conventional semiconductor laser device, the current blocking layer 17
Is made of GaAs, the current blocking layer 17 absorbs a large amount of red laser light oscillated from the active layer 13. For this reason, the internal loss in the optical waveguide is as large as about 20 cm ^−1, causing a problem that the operating current of the semiconductor laser device increases.

Further, due to the large operating current,
Since the heat generated from the semiconductor laser device is increased, the conventional semiconductor laser device cannot be mounted on an optical pickup device for DVD, which is currently mainstream, and is not suitable for practical use.

Further, in the conventional self-pulsation type semiconductor laser device, as described above, three crystal growth steps are required, so that there is a problem that it is difficult to reduce the cost.

In view of the above, a first object of the present invention is to realize a self-pulsation type semiconductor laser device having a low operating current, and a second object of the present invention is to make it possible to manufacture the semiconductor laser device in two crystal growth steps. And

[0014]

In order to achieve the above object, a semiconductor laser device according to the present invention comprises an active layer and a first conductivity type (Al _X1 Ga _{1 -X1)} formed on the active layer. ) _Z1
A first cladding layer made of In _{1 -Z1} P (0 ≦ X1 ≦ 1, 0 <Z1 <1), and a second conductivity type (Al _Y Ga _{1 -Y)} formed on the first cladding layer. ) _Z2 In _1-Z2 P (However,
0 ≦ Y ≦ 1, 0 <Z2 <1), a current block layer having a stripe region, and at least a first conductivity type (Al _X2 Ga _{1 -X 2} ) _{Z 3} In formed in the stripe region.
_A second cladding layer made of _1-Z3 P (0 ≦ X1 ≦ 1, 0 <Z3 <1), and Y is provided between X1, X2 and Y.
> X1 and Y> X2 hold, and a saturable absorption region that absorbs laser light generated from the active layer is formed in a region of the active layer immediately below the current blocking layer.

According to the semiconductor laser device of the present invention,
Since the aluminum composition (Y) of the current blocking layer is larger than the aluminum composition (X1) of the first cladding layer and the aluminum composition (X2) of the second cladding layer, the aluminum composition of the first cladding layer, the current blocking layer, and the second cladding layer is larger. The energy of each band gap can be larger than the energy for the oscillation wavelength of the laser light generated from the active layer.

With this configuration, the first cladding layer, the current blocking layer, and the second cladding layer are transparent to the laser light oscillated from the active layer. In particular, since the absorption of laser light by the current blocking layer can be prevented, the operating current of the semiconductor laser device according to the present invention can be reduced.

At the same time, since the current block layer is transparent to the laser beam, the light distribution of the laser beam oscillating from the region immediately below the sprite region in the active layer easily spreads to the region below the current block layer in the active layer. Thus, a saturable absorption region that absorbs laser light generated from the active layer can be formed in a region of the active layer immediately below the current blocking layer. Therefore, the semiconductor laser device according to the present invention can perform self-pulsation.

Further, since the current blocking layer has a stripe region and the second cladding layer is formed in the stripe region, the crystal growth process may be performed twice, thereby reducing the manufacturing cost of the semiconductor laser device. Can be reduced.

In the semiconductor laser device according to the present invention,
A first effective refractive index determined by the semiconductor multilayer structure including the second clad layer, the first clad layer, and the active layer above and below the stripe region, and the current block above and below the stripe region. The effective refractive index difference between the inside and outside of the stripe region, which is the difference from the second effective refractive index determined from the semiconductor multilayer structure including the layer, the first cladding layer, and the active layer, is 2 × 10 ⁻³ or more and 5 × 1
It is preferably 0 ^-3.

In this case, the size of the saturable absorbing layer formed on the active layer becomes appropriate, so that good self-pulsation can be obtained.

In the semiconductor laser device according to the present invention,
The active layer has a quantum well structure in which a plurality of quantum well layers and a plurality of barrier layers are stacked, and the total thickness of the quantum well layers is preferably 0.03 μm or more. In this way, good self-sustained pulsation can be obtained.

In the semiconductor laser device according to the present invention,
The thickness of the first cladding layer is 0.10 μm or more and 0.4
Preferably it is 5 μm or less. This way,
Good self-excited oscillation is obtained.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a semiconductor laser device according to one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross-sectional structure of a semiconductor laser device 100 according to one embodiment. As shown in FIG.
On an n-type GaAs substrate 101, an n-type cladding layer 102 composed of an n-type AlGaInP layer, an active layer 103 having a multiple quantum well structure, and a p-type (Al _X1 Ga _{1 -X1} ) _Z1I
a p-type first cladding layer 104 made of n _{1 -Z1} P (0 ≦ X1 ≦ 1, 0 <Z1 <1); and an n-type (Al _Y G
a _1-Y ) _Z2 In _{1 -Z2} P (where 0 ≦ Y ≦ 1, 0 <Z2 <
1), a current block layer 105 having a stripe region 105a, and a p-type (Al _X2 Ga _1-X2 ) Z ₃ In
_A p-type second cladding layer 106 made of _1-Z3 P (where 0 ≦ X2 ≦ 1, 0 <Z3 <1) and a contact layer 107 made of a p-type GaAs layer are sequentially formed. The active layer is composed of eight quantum well layers composed of a GaInP layer and Al _x
It has a multiple quantum well structure consisting of nine barrier layers consisting of Ga _1-X InP layers (where 0 ≦ X ≦ 1). An n-type electrode 108 is provided on the lower surface of the n-type GaAs substrate 101.
Are formed, and a p-type electrode 109 is formed on the upper surface of the contact layer 107.

The method for manufacturing the semiconductor laser device according to this embodiment is as follows.

First, on an n-type GaAs substrate 101, n
N-type AlGaInP layer to be the
GaInP layer (quantum well layer) to be the conductive layer 103 and
And Al_XGa_1-XInP layer (however, 0 ≦ X ≦ 1) (barrier
Layer), p-type (Al) to be the p-type first cladding layer 104_X1
Ga_1-X1) Z₁In_1-Z1P (however, 0 ≦ X1 ≦ 1, 0 <
Z1 <1) layer and n-type to be the current blocking layer 105
(Al_YGa_1-Y)_Z2In _1-Z2P (however, 0 ≦ Y ≦ 1, 0
<Z2 <1) layers were sequentially crystal-grown (first growth step)
After that, the n-type (Al_YGa_1-Y)_Z2In_1-Z2P for Pattani
Block having striped region 105a
The layer 105 is formed.

Next, after exposing to the stripe region 105a,
P-type first cladding layer 104 and current blocking layer 1
05 on the p-type second cladding layer 106
(Al _X2Ga_1-X2)_Z3In_1-Z3P (however, 0 ≦ X2 ≦
1, 0 <Z3 <1) layer and p serving as contact layer 107
Type GaAs layers are grown sequentially (second growth process)
Process), and the semiconductor laser device according to the present embodiment is obtained.
You.

Therefore, the semiconductor laser device according to the present embodiment can be formed by two crystal growth steps, so that the cost can be reduced.

In the semiconductor laser device according to the present embodiment, the p-type (Al
_{X1Ga1 -X1} ) _{Z1In1 -Z1P} (provided that 0 ≦ X1 ≦ 1, 0 <
Z1 <1) layer, n-type (Al
_{Y Ga 1-Y) Z2 In} 1-Z2 P ( where, 0 ≦ Y ≦ 1,0 <Z2
<1) p-type (Al _X2 Ga _1-X2 ) _Z3 In _{1 -Z3} P (0 ≦ X2 ≦
1, 0 <Z3 <1) Aluminum composition (X
1, Y, X2) have a relationship of Y> X1 and Y> X2.

According to the semiconductor laser device of this embodiment, the aluminum composition (Y) of the current block layer 105
Is larger than the aluminum composition (X1) of the p-type first cladding layer 104 and the aluminum composition (X2) of the p-type second cladding layer 106, so that the p-type first cladding layer 104, the current blocking layer 105, and the The energy of each band gap of the p-type second cladding layer 106 can be made larger than the energy for the oscillation wavelength of the laser light generated from the active layer 103.

In this case, the p-type first cladding layer 104, the current blocking layer 105, and the p-type second cladding layer 106 are transparent to the laser light oscillated from the active layer 103. The light distribution of the laser light oscillating from the region immediately below the sprite region 105a in
It can be easily extended to the region under the current block layer 105 in the active layer 103.

On the other hand, the current injected into the active layer 103 is
Since the current block layer 105 limits the region to a region immediately below the stripe region 105a, no current flows in a region of the active layer 103 immediately below the current block layer 105,
A saturable absorption region that absorbs laser light generated from the active layer 103 can be formed. Therefore, the semiconductor laser device according to the present embodiment can perform self-pulsation.

Table 1 shows a contact layer 107, a p-type second cladding layer 106, a current blocking layer 105, a p-type first cladding layer 104, an active layer, which constitute a semiconductor laser device according to one embodiment. The aluminum composition and the film thickness of the layer 103 and the n-type cladding layer 102 are shown.

[0034]

[Table 1]

As shown in [Table 1], the current blocking layer 1
05 (Y = 1.0) is larger than the aluminum composition (X1 = 0.7) of the p-type first cladding layer 104, and the aluminum composition (Y = 1.0) of the current blocking layer 105 is p It is larger than the aluminum composition (X2 = 0.6) of the second cladding layer 104 of the mold. [Table 1] shows that the current blocking layer 105 is an n-type (Al _Y Ga
Although _{1-Y) Z2 In 1-} Z2 P of aluminum composition (Y) indicates the case where 1, may contain gallium in the current blocking layer 105 aluminum composition is not one.

The active layer 103 includes a quantum well layer made of a GaInP layer and an Al _x Ga ₁ -x InP layer (X = 0.
5), the laser beam emitted from the active layer 103 has an oscillation wavelength of about 670 nm (energy: 1.85 eV).

The band gap energy of the p-type first cladding layer 104, the current blocking layer 105, and the p-type second cladding layer 106 is larger than the energy of the laser light oscillated from the active layer 103. Since the first cladding layer 104, the current blocking layer 105, and the p-type second cladding layer 106 become transparent to laser light oscillated from the active layer 103, the internal loss in the optical waveguide is several c.
m ^-3 and the operating current is reduced.

In the semiconductor laser device according to the present embodiment, p
-Type second cladding layer 106, p-type first cladding layer 10
The first effective refractive index determined by the semiconductor multilayer structure including the active layer 103 and the active layer 103, and the semiconductor including the current blocking layer 106, the p-type first cladding layer 104, and the active layer 103 existing above and below the stripe region 105a. The difference between the effective refractive index inside and outside the stripe region, which is a difference from the second effective refractive index determined from the multilayer structure, is 2 × 10 ⁻³ or more and 5 × 10 ⁻³ or more.
It is preferably ^-3 or less.

Hereinafter, the p-type second cladding layer 106 and the p-type first cladding layer 106 which are present above and below the stripe region 105a.
A first effective refractive index n ₁ determined by a semiconductor multilayer structure including a cladding layer 104, an active layer 103 and an n-type cladding layer 102, a current blocking layer 106 existing above and below the stripe region 105 a, and a p-type 1 cladding layer 104, active layer 103 and n-type cladding layer 102
Effective refractive index n determined from the semiconductor multilayer structure consisting of
_{2, which} is the difference between the effective refractive index inside and outside the stripe region (hereinafter simply referred to as the effective refractive index difference) Δn (= n ₁ −)
The relationship between n ₂ ) and self-pulsation will be described. In the present embodiment, the effective refractive index difference Δn is 3.2 × 10 ^−3.
Is set to

First, the principle of self-sustained pulsation of the semiconductor laser device according to this embodiment will be described with reference to FIGS.

FIG. 2A shows a range of a light distribution 110 of laser light oscillated from the active layer 103 in the semiconductor laser device according to the present embodiment, and FIG. 2B shows an effective refractive index difference. 2C shows the light distribution, FIG. 2D shows the gain distribution, and FIG. 2E shows the mode gain distribution.

In the semiconductor laser device according to this embodiment, as described above, since the current blocking layer 105 is transparent to the laser light oscillated from the active layer 103,
Since the laser beam is hardly absorbed by the current block layer 105, the laser beam considerably seeps into the current block layer 105. In the present embodiment, the effective refractive index difference Δn
Is set to a small value of 3.2 × 10 ⁻³ , as shown in FIG. 2A, the light distribution 110 is formed by the p-type first cladding layer 104 and the current blocking layer 105 in the active layer 103. To the lower area.

Most of the introduced current is confined in the stripe region 105a and the p-type first cladding layer 1
4, the current distribution (gain distribution) is reduced to the stripe region 105 as shown in FIG.
It spreads only as much as.

Accordingly, the light distribution shown in FIG.
The mode gain distribution represented by the product of the gain distribution shown in (d) is as shown in FIG. That is, although the light distribution 110 extends to the outside of the stripe region 105a, the gain distribution becomes a loss outside the stripe region 105a.
A loss occurs in a region outside the region 05a (a region indicated by hatching in FIG. 2E). Therefore, as shown in FIG. 2A, the stripe region 105a in the active layer 103 is formed.
Saturable absorption regions 111 are formed on both sides.

FIG. 3 shows the light output when the semiconductor laser device according to the present embodiment is self-oscillated at room temperature (25 ° C.) when the emitting end face is in an uncoated state (a state in which no coating layer is formed). 3 shows a time response waveform of the time chart. As can be seen from FIG. 3, a stable optical pulse train is obtained,
Satisfactory self-excited oscillation is realized. The frequency of self-excited oscillation is 613 MHz.

FIG. 4 shows the results of measuring the optical output-current characteristics when the semiconductor laser device according to the present embodiment is self-oscillated at room temperature when the emitting end face is in an uncoated state. In the graph, the solid line represents the characteristics of the semiconductor laser device according to the present embodiment, and the broken line represents the characteristics of the conventional semiconductor laser device.

As can be seen from FIG. 4, according to the conventional semiconductor laser device, the operating current at the time of light output of 5 mW is 86.
According to the semiconductor laser device according to the present embodiment, the operating current at the time of light output of 5 mW is 56.
It was 6 mA, and it was confirmed that the operating current could be reduced to about two thirds of the conventional one.

By the way, in order to cause the semiconductor laser device to self-oscillate, the saturable absorption region 111 is required. In the present embodiment, the current blocking layer 105 is
Since it is transparent to the laser light oscillating from 03, the effective refractive index difference Δn can be set to a small value. For this reason, the light distribution 110 can be greatly expanded to the outside of the stripe region 105a, so that the saturable absorption region 111 having a size sufficient for self-pulsation can be obtained.

The preferred range of the effective refractive index difference Δn for causing good self-sustained pulsation will be described below.

When the effective refractive index difference Δn is smaller than 2 × 10 ⁻³ , the light distribution 110 becomes large, and the area of the saturable absorption region 111 becomes too large. Does not saturate. That is, the saturable absorption region 111 has only a function as a simple absorber, and self-pulsation does not occur. On the other hand, when the effective refractive index difference Δn is smaller than 2 × 10 ⁻³ , the waveguide structure becomes anti-refractive index, and the transverse mode becomes very unstable.

On the other hand, when the effective refractive index difference Δn is larger than 5 × 10 ⁻³ , the light distribution 110 becomes small, and the saturable absorption region 111 does not function sufficiently, so that self-pulsation does not occur.

Therefore, in order to cause good self-sustained pulsation, the effective refractive index difference Δn must be 2 × 10 ⁻³ or more and 5 × 10 ⁻³ or more.
It must be less than 10 ^-3 .

FIG. 5A shows the semiconductor laser device according to the present embodiment, in which the number of quantum well layers of the active layer 103 and the thickness of the p-type first cladding layer 104 are changed to change the effective refractive index difference. The result of measuring the relationship between Δn and the half width of the spectrum during laser oscillation is shown. FIG. 5B shows the spectrum of the laser beam oscillating in the vertical single mode, and FIG. 5C shows the spectrum of the laser beam oscillating in the vertical multimode. At the time of self-sustained pulsation, the spectrum of the laser beam is in a vertical multi-mode, so that the half width of the spectrum is about 1 nm. Therefore, whether or not self-sustained pulsation has occurred can be determined by measuring the half-width of the spectrum.

In FIG. 5A, ◆ indicates that the number of well layers is seven.
Indicates the case where the thickness of the first cladding layer 104 is 0.15 μm.
Indicates a case where the number of well layers is 7 and the thickness of the first cladding layer 104 is 0.25 μm, and ○ indicates a case where the number of well layers is 8 and 1 clad layer 10
4 shows a case where the thickness is 0.20 μm, ☆ shows a case where the number of well layers is eight and the first cladding layer 104 has a thickness of 0.25 μm, and Δ shows a case where the number of well layers is eight. First cladding layer 1
04 shows a case where the thickness is 0.30 μm.

From FIG. 5 (a), it was confirmed that self-oscillation occurred when the value of the effective refractive index difference Δn was 2.5 × 10 ⁻³ or more and 4.2 × 10 ⁻³ or less. According to the results shown in FIG. 5A, when the value of the effective refractive index difference Δn is 2.5 × 10 ⁻³ or less and 4.2 × 10 ⁻³ or more, no self-excited oscillation occurs. If the effective refractive index difference Δn is not less than 2 × 10 ^{−3 and not} more than 5 × 10 ⁻³ , the number of quantum well layers and the number of active layers 10
By optimizing the total thickness of the quantum well layers constituting the third or the thickness of the p-type first cladding layer 104, self-pulsation can be caused.

Hereinafter, the relationship between the total thickness of the quantum well layers constituting the active layer 103 (total thickness of the well layers) and the self-excited oscillation characteristics will be described.

FIG. 6 shows that the value of the effective refractive index difference Δn is 3.2 ×
The graph shows the relationship between the total thickness of the well layer and the full width at half maximum when the ^wavelength is set to about 10 ⁻³ . ○ in FIG.
Are, in order from the left, 6 well layers having a thickness of 0.0053 μm.
When there are seven layers (total thickness: 0.0053 × 6 μm), and when there are seven well layers with a thickness of 0.0053 μm (total thickness: 0.0053 × 7 μm), the thickness is 0. 0053
When there are eight μm well layers (total thickness: 0.005
3 × 8 μm) and six well layers having a thickness of 0.0080 μm (total thickness: 0.0080 × 6 μm).

FIG. 6 shows that the total thickness of the quantum well layers is 0.0
It can be seen that self-oscillation occurs when the thickness is about 35 μm or more. In other words, by increasing the total thickness of the quantum well layer,
It can be seen that self-excited oscillation occurs when the volume of the saturable absorption region 111 is secured.

FIG. 6 shows that the effective refractive index difference Δn is 3.2 × 10 ^-3.
The effective refractive index difference Δn is 2
If the total thickness of the quantum well layers is 0.030 μm or more, self-sustained pulsation occurs when the thickness is reduced to about × 10 ^{−3 to} 3 × 10 ⁻³ .

The relationship between the thickness of the p-type first cladding layer 104 and the self-sustained pulsation characteristics will be described below.

FIG. 7 shows that the value of the effective refractive index difference Δn is 3.2 ×
When the active layer 103 is set to about 10 ⁻³ and the active layer 103 is set to a quantum well structure in which eight well layers each having a thickness of 0.0053 μm are stacked, the thickness of the p-type first cladding layer 104 is reduced. It shows the relationship with the maximum self-oscillation temperature (the highest temperature at which self-oscillation occurs). In FIG. 7, ○ indicates a case where self-sustained pulsation occurs, and x indicates a case where self-sustained pulsation does not occur.

As can be seen from FIG. 7, if the thickness of the p-type first cladding layer 104 is about 0.1 μm, the room temperature (2
(5 ° C). p-type first cladding layer 104
With the increase in thickness of about 0.3 μm,
Self-excited oscillation occurs even at about 0 ° C.

On the other hand, when the thickness of the p-type first cladding layer 104 becomes larger than about 0.3 μm, the maximum self-excited oscillation temperature decreases, and the thickness of the p-type first cladding layer 104 becomes zero. Self-excited oscillation up to about .45 μm
When it is larger than about m, self-excited oscillation stops.

Therefore, in order to cause self-excited oscillation,
The thickness of the p-type first cladding layer 104 is preferably 0.1 μm or more and 0.45 μm or less. In order to cause self-excited oscillation at a temperature of about 60 ° C. or more, the p-type first
When the thickness of the cladding layer 104 is 0.2 μm or more and 0.4
It is preferable to set it to μm or less.

[0065]

According to the semiconductor laser device of the present invention, the current blocking layer is made of a semiconductor material that is transparent to the oscillation wavelength of the laser light generated from the active layer.
Since a saturable absorbing layer that absorbs laser light generated from the active layer is formed in a region of the active layer immediately below the current blocking layer, self-pulsation can be performed.

Further, since the current blocking layer has a stripe region and the second cladding layer is formed in the stripe region, the crystal growth step may be performed twice, so that the manufacturing cost of the semiconductor laser device is reduced. Can be reduced.

[Brief description of the drawings]

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

FIGS. 2A to 2E are diagrams illustrating the principle of self-excited oscillation of a semiconductor laser device according to an embodiment of the present invention, and FIG. The distribution range is shown, (b) shows the effective refractive index difference, (c) shows the light distribution, (d) shows the gain distribution, and FIG. 2 (e) shows the mode gain distribution.

FIG. 3 is a diagram showing a time response waveform of an optical output when the semiconductor laser device according to one embodiment of the present invention self-oscillates at room temperature.

FIG. 4 is a diagram showing light output-current characteristics when the semiconductor laser device according to one embodiment of the present invention self-oscillates at room temperature.

FIG. 5A is a diagram illustrating a relationship between an effective refractive index difference and a spectral half width at the time of laser oscillation in a semiconductor laser device according to an embodiment of the present invention, and FIG. FIG. 4 is a diagram illustrating a spectrum of a laser beam oscillating in the vertical multi-mode, and FIG.

FIG. 6 is a diagram showing a relationship between the total thickness of a well layer and a spectral half width in a semiconductor laser device according to an embodiment of the present invention.

FIG. 7 is a diagram showing the relationship between the thickness of the p-type first cladding layer and the maximum self-excited oscillation temperature in the semiconductor laser device according to one embodiment of the present invention.

FIG. 8 is a sectional view of a conventional semiconductor laser device.

FIG. 9 is a diagram showing light output-current characteristics in a conventional semiconductor laser device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 semiconductor laser device 101 n-type GaAs substrate 102 n-type cladding layer 103 active layer 104 p-type first cladding layer 105 current blocking layer 105 a stripe region 106 p-type second cladding layer 107 contact layer 108 n-type electrode 109 p Type electrode 110 Light distribution 111 Saturable absorption layer

Claims (5)

[Claims] An active layer and a first conductive type (Al _X1 Ga _{1 -X 1} ) _Z1 In _{1 -Z1} P formed on the active layer (wherein
A first cladding layer composed of 0 ≦ X1 ≦ 1, 0 <Z1 <1) and a second conductivity type (Al _Y Ga _1-Y ) _Z2 In _1-Z2 P formed on the first cladding layer. (However, 0 ≦ Y ≦ 1, 0
<Z2 <1), a current block layer having a stripe region, and at least a first conductivity type (Al _X2 Ga _1-X2 ) _Z3 In _{1 -Z3} P (0 ≦ X1) formed in the stripe region. ≦ 1, 0 <Z3 <1), and a relationship of Y> X1 and Y> X2 is established between X1, X2, and Y, and the active layer is directly below the current blocking layer. A saturable absorption region for absorbing a laser beam generated from the active layer in the region (a). 2. A first effective refractive index determined by a semiconductor multilayer structure including the second clad layer, the first clad layer, and the active layer existing above and below the stripe region, and an upper and lower region outside the stripe region. The effective refractive index difference between the inside and outside of the stripe region, which is the difference from the second effective refractive index determined from the semiconductor multilayer structure including the current blocking layer, the first cladding layer, and the active layer, is 2 × 10
^2. The semiconductor laser device according to claim 1, wherein the value is not less than ^{−3 and not} more than 5 × 10 ⁻³ . 3. The energy of a band gap of each of the first cladding layer, the current blocking layer, and the second cladding layer is larger than energy with respect to an oscillation wavelength of laser light generated from the active layer. The semiconductor laser device according to claim 1. 4. The active layer has a quantum well structure in which a plurality of quantum well layers and a plurality of barrier layers are stacked, and the total thickness of the quantum well layers is 0.03 μm or more. The semiconductor laser device according to claim 1, wherein: 5. The thickness of the first cladding layer is 0.10.
2. The semiconductor laser device according to claim 1, wherein the diameter is not less than μm and not more than 0.45 μm.