JPH10154843A - Semiconductor laser device and optical disk device using the same - Google Patents

Abstract

[PROBLEMS] To provide an improved semiconductor laser device capable of maintaining a high and stable optical output until a kink is generated and having a good production yield. A semiconductor laser having a double hetero structure including an active layer serving as a light emitting region and two cladding layers vertically sandwiching the active layer on a semiconductor substrate, and a stripe structure for current injection provided in the double hetero structure. In the element
The width of the stripe structure has at least one narrow portion, and the width is changed along the length direction of the resonator.

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 for use as a light source for optical information equipment and the like.

[0002]

2. Description of the Related Art Generally, in a semiconductor laser having an oscillation wavelength in the near-infrared to visible range, a deterioration phenomenon that a laser end face emitting light is destroyed when the light output is increased easily occurs. One of the causes of the edge destruction is optical damage due to local thermal destruction. It is necessary to lower the light density inside the active layer in order to suppress the end face breakdown and increase the light output. For example, it is general to widen the region of the laser light guide by using a relatively wide stripe structure having a width of about 5 μm, for example. It is.
The stripe structure is a structure for supplying carriers to the active layer by current injection, and the light emitting region of the active layer has the same stripe shape because it is determined by this structure.

However, as the stripe width is increased, the loss not only for the fundamental mode but also for higher-order modes decreases. In such a case, when the light output is increased by increasing the current, the high gain portion becomes unevenly distributed inside the laser, and a higher-order mode occurs. When a higher-order mode occurs, the linearity of the light output-current characteristic is impaired, and a step change in light output called kink appears in the process of increasing the current. This phenomenon is caused by instability of laser oscillation and is not desirable.

On the other hand, a current blocking layer is provided on the stripe structure to prevent leakage of current to the outside. For example, AlGaInP (aluminum, gallium, indium, phosphorus) semiconductor laser (emission wavelength: 600 to 700 nm)
In this case, a crystal having a relatively small band gap, such as GaAs (As: arsenic), is usually used as a current blocking layer, and this layer is a layer that absorbs laser light.
When the stripe width is reduced to control the waveguide mode, of the light to be reflected by the cladding layer and returned to the active layer,
The amount absorbed by the block layer increases, and the luminous efficiency decreases.

[0005] Therefore, the stripe width is required to have a certain width from the viewpoint of improving the luminous efficiency. However, such a structure is basically required for some higher-order modes such as primary and secondary modes. It must be a multimode waveguide that can be generated. Usually, the current is set so as to oscillate in the fundamental mode with the smallest propagation loss using the same waveguide structure.

As an example of a conventional semiconductor laser having the above waveguide structure, FIG. 13 shows an element disclosed in Japanese Patent Application Laid-Open No. 7-273398. The semiconductor laser has a double hetero structure in which an active layer 3 is sandwiched between two cladding layers 2 and 4. The cladding layer 4 has a mesa-shaped upper portion (having a region protruding in a convex shape with respect to the main surface of the substrate). Shape). A mesa-shaped portion (that is, a protruding portion) of the cladding layer 4 has a stripe structure, whereby a stripe-shaped light emitting region serving as a refractive index waveguide is formed inside the active layer 3. A cross section parallel to the upper surface of the stripe-structured element (see FIG. 13B) has an elongated linear shape with a constant width of W and a length of L (all conventional semiconductor lasers having a stripe-shaped light emitting region have a width of W. Is constant). With this stripe structure, the resonator length becomes L.

However, in a conventional semiconductor laser,
Even if the current is set as described above, kink may occur at a very low light output under certain conditions. It is the case where the primary mode is involved and the following relational expression is satisfied between the basic mode and the primary mode.

(Β ₀ −β ₁ ) L = nπ β ₀ , β ₁ : Propagation constants of the fundamental mode and the primary mode, respectively n: Integer (n = 1, 2, 3,...) It shows that the phase difference between the two modes (transverse mode) while the light makes one round trip through the resonator is exactly an integer multiple of 2π, and at this time, interference occurs between the fundamental mode and the first mode, and therefore, the kink Occurs.

At this time, the light intensity distribution inside the laser has a meandering distribution in the stripe-shaped light emitting region in the active layer, and the emission direction of the beam output from the end face of the laser resonator changes greatly with the light output. I do. This phenomenon is
It is called beam steering [for example, IEICE Technical Report LQE95-84, pp. 15-20]
Pp. (October 1995)]. This beam steering causes a disadvantage that, for example, when a laser beam is coupled to an optical fiber, a coupling loss increases at a certain drive current or more.

The above publication describes a method for setting the resonator length so that the above equation is not satisfied. However, as will be apparent from the above equation, interference occurs even when the propagation constant changes. In addition, the situation of the interference changes due to a slight change in the resonator length or the propagation constant. On the other hand, the propagation constant depends on the carrier concentration and gain distribution inside the laser, operating conditions such as operating temperature and drive current, the width of the stripe structure, and the like. Therefore, in order to keep the light output level (hereinafter referred to as “kink level”) until the occurrence of kink,
It is not enough to set the resonator length alone, so that other dimensions such as the stripe width are strictly controlled so that interference does not occur even if the operating conditions change in the range of use, and the material composition and manufacturing conditions are strictly controlled. Strict process accuracy is required to suppress this, and there is a problem that it is difficult to manufacture an element having good light output-current characteristics with high yield.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, to maintain a high and stable light output until the occurrence of kink, and to improve the production yield with a good improvement. To provide a semiconductor laser device.

[0012]

The object of the present invention is attained by providing at least one narrow portion in the width of the stripe structure in the double hetero structure and changing the width along the length direction of the resonator. Can be settled. By adopting such means, it is possible to increase the propagation loss for higher-order modes and to suppress the occurrence of kink at a low optical output.

FIG. 1 is a sectional view showing an example of a stripe structure having a changed width. In the figure, reference numeral 50 denotes a stripe structure. This figure shows a case where the number N of the narrow portions of the stripe structure 50 is three. The width of the narrow portion is W ₁ , and the width of the opposite wide portion is W ₀ . In this structure, the propagation loss coefficient alpha ₀ and 1 order mode wide section width W ₀ of the difference Δα in propagation loss coefficient alpha ₁ of the fundamental mode with the 1,2,4 or the number N of the narrow portion Difference ΔW of narrow width W ₁
(= W ₀ −W ₁ ) is shown in FIG. In the calculation, the width W ₀ was fixed at 5 μm, and the cavity length L was 600 μm. From the figure, it is understood that the loss difference Δα between the modes increases as the width difference ΔW increases and the number N of the narrow portions increases. When the loss difference Δα increases, interference between the two decreases and the kink level increases.

When ΔW = 0, that is, in the case of the conventional stripe structure having a constant width, the loss difference Δα is about 6 cm ⁻¹ in FIG. For example, in the case of a short-wavelength high-power laser using AlGaInP, when a rewritable optical disk device suitable for the application is adopted, the loss difference Δα is 1.5 times or more from the above 6 cm ⁻¹ (dotted line in FIG. It is desired to increase the range. This is because the kink level may be 20 mW when the width is constant, whereas at least 30 mW of light output is required for rewriting, and from that, 1.5 times or more is calculated. You. In this way, a kink level of 30 mW or more can be secured. Therefore, the number N of narrow portions and the width difference ΔW are set such that the loss difference Δα is equal to or larger than the dotted line in FIG.

On the other hand, when the number N of the narrowed portions is increased, the loss difference Δα is increased, so that the width difference ΔW can be reduced. However, when the number N of the narrowed portions is increased, the propagation loss coefficient α of the fundamental mode is increased. ₀ itself increases. Figure 3 shows the calculation results.
Shown in Since the loss factor alpha ₀ in the case of N = 0 is 12cm ^-1, to increase the kink level without too large a propagation loss coefficient alpha ₀ by the narrow parts N and one to eight ranges Can be. Although not shown,
When the number N of the narrow portions is eight, the width difference ΔW is 0.3 μm.
It has been found that m is possible.

The reason why the propagation loss coefficient α ₀ of the fundamental mode increases as the number N of the narrow portions increases is that modes propagating as the stripe width per unit length increases become scattered. FIG. 4 shows the relationship between the width change per 100 μm and the scattering loss of the fundamental mode. The scattering loss is about 2 dB for a width change of 5 μm. This value is equivalent to the propagation loss in the entire resonator when ΔW = 0. If the scattering loss further increases, the deterioration of device characteristics due to an increase in threshold current and a decrease in efficiency cannot be ignored. Therefore, the width change amount per 20 μm is 1
It has been found that it is desirable to keep the thickness below μm.

From the above conclusions, in the semiconductor laser of the present invention, the range of the width difference ΔW is 0.3 μm to 2 μm, and the number of narrow portions N
From 1 to 8, a high kink level can be obtained, and interference is reduced due to an increase in the propagation loss difference between the fundamental mode and the primary mode. Is possible, and the production yield can be increased.

[0018] In the above has been calculated by fixing the width W ₀ of the wide portion in 5 [mu] m, a width W ₀ can be obtained similar results in the range of 4Myuemu～7myuemu. As described above, if the stripe width is wide, the loss for the higher-order mode is insufficient, and if the stripe width is narrow, the propagation loss of the fundamental mode is increased and the end face is broken. The range of 4 μm to 7 μm is set as an optimum range from these circumstances. In this case, the width W _{1 of the} narrow portion
Is set to _{W 0 -2μm <W 1 <W} 0 -0.3μm.

In an optical disc device, a semiconductor laser may be driven by a pulse current to require a high optical output of about 50 mW. For such a requirement, the loss difference Δα is set to be at least twice the 6 cm ⁻¹ .
As a result, in consideration of the propagation loss of the fundamental mode, the optimal range is such that the range of the width difference ΔW is 1 μm to 1.5 μm and the number N of the narrow portions is 3 to 5.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the semiconductor laser device according to the present invention will be described below in more detail with reference to some embodiments shown in the drawings. The same symbols in FIGS. 1 to 13 denote the same or similar objects.

[0021]

【Example】

Embodiment 1 FIG. 5 shows an AlGaInP semiconductor laser device adopting a stripe structure in which the number N of narrow portions is three. 5A is a perspective view of a laser chip, FIG. 5B is a sectional view of a stripe structure, and FIG. 5C is a sectional view of an element. FIG. 5b,
In 5c, 4a is the first clad layer in contact with the active layer 3 of the bisected clad layer, 4b is the other second clad layer of the bisected clad layer, and 5 is the clad layer 4
a, a buffer layer formed above the cladding layer 4b; 8, a current blocking layer for preventing current flowing through the cladding layer 4b from leaking to the outside; The contact layer 10 formed on the buffer layer 7 and the current block layer 8 is a p-side electrode,
Reference numeral 1 denotes an n-side electrode.

The cladding layer 4b was formed in a ridge shape (trapezoid). A stripe structure is formed at the bottom of the cladding layer, and the stripe width W is shown in the element cross section. Width W varies between the width W ₀ of the constriction width W ₁ and the wide portion. The width difference ΔW was set to 1 μm, and the stripe width W was periodically changed in a tapered shape. The resonator length L is set to 4
It varied between 00 μm and 800 μm.

Next, the manufacturing process of the present element will be described below. First, MOCVD (Metal Organic Chemical Vapor D
eposition) An n-AlGaInP cladding layer 2 (1.8 μm thick) was formed on a GaAs substrate 1 using a crystal growth apparatus.
InP / AlGaInP multiple quantum well structure active layer 3, p-
AlGaInP first cladding layer (film thickness 0.2 μm) 4a, p
-GaInP etching stop layer 5, p-AlGaInP second
A cladding layer (thickness: 1.3 μm) 4b, a p-GaInP buffer layer 7, and an n-GaAs cap layer (not shown because they are removed during the process) were sequentially laminated.

Next, TCVD (Thermal Chemical Vapor)
Deposition) After forming the SiO ₂ film (not shown) by a device, to process the SiO ₂ film in a stripe shape via a photolithography process. In the photolithography process, SiO ₂
A mask whose film shape was the shape of the lower surface of the second cladding layer 4b in FIG. 5C was used. Using the SiO ₂ film as a mask,
aAs cap layer, GaInP buffer layer 7 and AlGaIn
The P cladding layer 4b was removed by chemical etching to form a ridge-like normal mesa stripe.

Subsequently, n-GaAs is formed by burying twice.
After forming the current blocking layer 8 and the p-GaAs contact layer 9, a p-side electrode was formed on the contact layer 9, and an n-side electrode 11 was formed on the back surface of the substrate 1. Finally, it was cleaved into chips.

The light output current characteristics of the device manufactured by the pulse current were evaluated. FIG. 6 shows the result. Resonator length L
However, the kink level periodically changed, but the minimum value of the kink level was as high as 50 mW. Also, in the element in which the resonator length L was set to 700 μm, no kink was generated up to an optical output of 60 mW or more even when the operating temperature and the pulse width were changed, and good optical output current characteristics could be obtained.

Next, a semiconductor laser having the active layer 3 having a GaInP single quantum well structure was manufactured. Other structures were the same as above. As a result of evaluation, the same result as described above was obtained in the case of this element.

For comparison, a conventional device having a linear stripe structure and the same structure as the above-mentioned AlGaInP laser was manufactured and its characteristics were measured. Fig. 6 shows the results.
At the same time. With the change of the resonator length L, the kink level periodically changed and distributed in the range of 20 to 60 mW. There are few cases where the kink level exceeds 50 mW, and these are concentrated in a limited range of the resonator length L. Also,
When the operating temperature and the drive current waveform were changed, there were many devices where kink occurred at a very low light output. In the structure of the conventional device, in order to secure a kink level of 50 mW or more, the device manufacturing process must be strictly controlled.
It was difficult to obtain a device having good characteristics with good yield.

In the above description, a tapered shape is adopted as a method of changing the stripe width.
For example, as long as the rate of change does not exceed 1 μm, it may be a sinusoidal waveform with a smooth change, or a straight line parallel to the direction of the resonator length may be provided between the tapers. The same effect as in the case of the tapered shape can be obtained.

In the present embodiment, the device has a stripe structure at the bottom of the second cladding layer 4b.
The stripe-shaped light emitting region is applicable to all semiconductor lasers formed in the active layer (for example, a buried hetero semiconductor laser), and the width of the stripe structure for supplying carriers to the active layer is set in the same manner as described above. It is needless to say that the same effect can be obtained.

Example 2 A semiconductor laser having a stripe structure in which two narrow portions were provided at the center and the width W ₂ at the end face of the stripe width was wider than the width W _{0 of the} wide portion was manufactured. FIG. 7 shows a cross section of the stripe structure.
The reason why the width is increased at the end face is to reduce the light density near the end face. The element structure other than the stripe structure and the manufacturing process were the same as those in the first embodiment. The kink level of the manufactured device was 50 mW or more, and it was found that even if a narrow portion was provided in a central portion, a higher-order mode could be suppressed. In addition, due to the reduction of the light density near the end face,
The light output level causing end face damage was increased, and the effective light output was improved. At 60 ° C., the light output level causing end face damage exceeded 140 mW. On the other hand, in the conventional linear stripe structure, the output was about 100 mW, so that an output improvement of 40% or more could be obtained by the present invention.

Next, an element was fabricated in which the cross-sectional structure of the second cladding layer 4b was in the shape of an inverted mesa ridge. FIG. 8 shows a cross-sectional structure of the element. By increasing the volume of the cladding layer 4b, the element resistance was reduced, and an element which can be driven at a low voltage was obtained.

In the above description, the width of both the front end face from which the light output is taken out and the rear end face opposite thereto are increased. However, the present invention is not limited to this, and the same applies if only the width of the front end face is increased. The effect of can be obtained. This is because the light density is lower on the rear side than on the front side.

In the description of the first and second embodiments, 600 n
AlGaInP laser with emission wavelength in m-band and similar Ga
Although an InP laser has been described, the present invention can be applied to a high-power laser using another material system. In that case, since the refractive index of the laser structure and the laser structure itself are different, it is necessary to change various constants according to each structure. Hereinafter, as examples of other materials, two examples of ZnSe-based and GaN-based materials will be described, and the laser will be described.

<Embodiment 3> FIG. 9 shows a ZnCdSSe semiconductor laser device employing a stripe structure in which the number N of narrow portions is three. FIG. 9a is a cross-sectional view of the stripe structure, FIG.
Is a sectional view of an element. This device emits blue-green laser light. In this embodiment, first, a ZnSe buffer layer 312, a ZnMgSSe cladding layer 302, a ZnC
A dSSe quantum well active layer 303, a ZnMgSSe cladding layer 304, a ZnSe buffer layer 307, and a p-GaAs contact layer 309 were sequentially laminated by molecular beam epitaxy.

Next, an SiO ₂ film (not shown) is formed on the substrate having the multilayer structure formed as described above, and the contact layer 30 is formed by photolithography using the SiO ₂ film as a mask.
9. Processing the buffer layer 307 into a ridge-shaped stripe;
The clad layer 304 was partially processed into a ridge-shaped stripe. After the insulating film 308 was embedded in the side surfaces of the ridge-shaped stripe, the p-side electrode 10 and the n-side electrode 11 were formed and cleaved into a laser chip.

The stripe structure of this embodiment is formed on the lower surface of the ridge-shaped stripe portion of the cladding layer 304. The change amount ΔW of the stripe width was 1.5 μm.
Further, the resonator length is set to 5 in the range of 400 μm to 1000 μm.
A plurality of devices with 0 μm each were manufactured.

The light output current characteristics were evaluated by driving with a pulse current. Resonator length 450μm, 650μm, 850μ
The minimum value of the kink level was about 45 mW in the device of m, but was 50 mW or more in all the other devices, and a light output current characteristic with good linearity could be obtained.

Embodiment 4 FIG. 10 shows an InGaN / AlGaN semiconductor laser device adopting a stripe structure in which the number N of narrow portions is six. 10A is a perspective view of a laser chip, FIG. 10B is a cross-sectional view of a stripe structure, and FIG.
Is a sectional view of an element. This device is obtained by laminating a GaN-based semiconductor crystal on a sapphire substrate, and emits laser light in a blue to ultraviolet range.

In this embodiment, first, a GaN buffer layer 412, an AlGaN cladding layer 402, and an InGaN / Al layer are formed on a sapphire substrate 401 by metal organic chemical vapor deposition.
GaN quantum well active layer 403, AlGaN cladding layer 40
4. A GaN contact layer 409 was sequentially formed.

Next, a silicon nitride film (not shown) was formed on the substrate having the multilayer structure formed as described above by a CVD method, and the silicon nitride film was processed into a stripe shape through a photolithography process. Subsequently, using the silicon nitride film as a mask, the contact layer 409 is processed into a ridge-like stripe by dry etching, and the cladding layer 40 is formed.
4 was processed into a ridge-shaped stripe halfway. After the crystal surface was chemically treated, an insulating layer 408 was formed on a side surface of the ridge-shaped stripe by a CVD method. Thereafter, a contact portion for forming an electrode was provided through a photolithography process and an etching process, and a p-side electrode 410 and an n-side electrode 411 were deposited on the contact portion. Finally, the resonator end faces of the element were formed by dry etching, and divided into chips by dicing.

Although the current confinement is performed by the insulating layer 408 in this structure, the layer may be embedded in a semiconductor such as GaN or AlGaN.

The stripe structure of this embodiment is formed on the lower surface of the ridge-shaped stripe portion of the cladding layer 404. The change amount ΔW of the stripe width was 1.5 μm.
In this structure, since the insulating layer 408 is used for current confinement,
The amount of change ΔW and the number of narrow portions N compared to the first and second embodiments.
Is taking a large amount.

As a result of evaluating the light output current characteristics of the device,
A kink level of 40 mW or more could be obtained even though the element had an extremely short wavelength.

<Embodiment 5> FIG. 11 shows an optical disk apparatus to which the semiconductor laser device of the present invention is applied. In the figure, 31 is a semiconductor laser device of the present invention, and 32 is a well-known waveform conversion circuit. For others, a general structure [for example, Hitachi Review Journal, Vol. 65, No. 10, pp. 691 to 6
96 (October 1983)].

At the time of recording, in the waveform conversion circuit 32, the pulse portion of the pulse-like input signal is divided into a plurality of narrow pulses. The semiconductor laser element 31 is driven by the output signal of such a plurality of pulses of the waveform conversion circuit 32, and emits a laser beam intermittently in a portion having a pulse. The laser light is applied to a recording layer 38 on an optical disk substrate 37 via a coupling lens 33, a beam splitter 34, a galvanometer mirror 35, and a focusing lens 36, and a pit (hole) 42 corresponding to an input signal is formed in the recording layer 38. Is formed in the recording groove 41.

As described above, it is a well-known technique that the drive signal is converted into a signal including a plurality of pulses in a portion having a pulse, thereby improving the shape of the pit 42 and the recording density. The amplitude of each of the multiple pulses must naturally be higher than for a single pulse. For example, while the light output of a single pulse is about 30 mW, in the case of a plurality of pulses, 40 mW to 50 mW is required.

In this case, the following method is often used for setting the laser drive current in order to simplify the laser drive circuit. Extrapolating from the _two operating currents I ₁ and I ₂ to obtain the optical outputs P ₁ and P ₂ , the optical output P ₀ required for recording is obtained.
It is a method of determining the operating current I ₀ to obtain.
However, if a kink appears in the light output current characteristic as in the conventional case shown in FIG. 12, a light output required for recording cannot be obtained, and an operation failure occurs. In a device having a conventional structure, if an operating temperature or a drive current waveform changes, a kink may occur at a low optical output as shown in FIG. 12, and reliability may be lacking in some cases. According to the semiconductor laser of the present invention, it is possible to avoid the occurrence of kink regardless of the operating conditions at the optical output required for recording as shown in FIG. An optical disk device can be realized.

At the time of reproduction, the semiconductor laser element 31 is continuously oscillated with a low optical output, and the light beam reflected and reflected by the recording film 38 of the disk substrate 37 is changed to the signal detector 3.
At 9, it is extracted as an electric signal. A part of the light beam is sent to the focus detector 40, and the focusing lens 36 is focused.

[0050]

According to the present invention, by employing a stripe structure having a varied width, it is possible to increase the light output until the occurrence of a kink, thereby suppressing the occurrence of beam steering at a low output. . Further, in the structure in which the stripe width is increased near the laser end face, the light density near the end face can be reduced, so that the light output until the end face is destroyed can be increased. Further, by using the optical disk as a light source for optical disk recording, a high-density optical disk can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view for explaining a stripe structure of a semiconductor laser device according to the present invention.

FIG. 2 is a curve diagram for explaining a relationship between a width change amount of a stripe structure and a propagation loss difference between modes.

FIG. 3 is a curve diagram for explaining a relationship between a propagation loss coefficient of a fundamental mode and the number of narrow portions in a stripe structure.

FIG. 4 is a curve diagram for explaining the relationship between the scattering loss of the fundamental mode and the amount of change in the stripe width.

FIG. 5 is a perspective view and a cross-sectional view for explaining a first embodiment of the semiconductor laser device according to the present invention.

FIG. 6 is a diagram for explaining evaluation results of the first embodiment.

FIG. 7 is a sectional view for explaining a second embodiment of the present invention.

FIG. 8 is a sectional view for explaining a modification of the second embodiment of the present invention.

FIG. 9 is a sectional view for explaining a third embodiment of the present invention.

FIG. 10 is a perspective view and a cross-sectional view for explaining a fourth embodiment of the present invention.

FIG. 11 is a perspective view and a waveform diagram for explaining a fifth embodiment of the present invention.

FIG. 12 is a curve diagram showing light output current characteristics.

FIG. 13 is a perspective view and a sectional view for explaining a conventional semiconductor laser device.

[Explanation of symbols]

1 ... substrate 2,4,4a, 4b, 302,304,402,404
... clad layer 3, 303, 403 ... active layer 31 ... semiconductor laser element 50 ... stripe structure L ... resonator length W ... stripe width W ₀ ... wide part width W ₁ ... narrow part width W ₂ ... stripe width at end face

Claims (12)

[Claims] 1. A semiconductor device comprising a semiconductor substrate having a double heterostructure comprising an active layer serving as a light emitting region and cladding layers sandwiching the active layer above and below, and a stripe structure for injecting current into the active layer. In a semiconductor laser device provided in a double hetero structure, the stripe structure has at least one narrow portion in its width, so that the width changes along the length direction of the resonator. Semiconductor laser device. Wherein said stripe structure is to the width W ₀ of the wide portion opposite to the width W ₁ of the narrow section, 4 [mu] m <W ₀ <7 [mu] m, W
2. The semiconductor laser device according to claim 1, wherein ₀₋₂ μm <W ₁ <W ₀ −0.3 μm. 3. The stripe structure according to claim 1, wherein the number of narrow portions is 1 to 3.
3. The semiconductor laser device according to claim 1, wherein the number is in the range of eight. 4. The stripe structure according to claim 1, wherein the number of narrow portions is three to three.
4. The semiconductor laser device according to claim 3, wherein the number is in five ranges. 5. The device according to claim 1, wherein the width of the stripe structure does not change more than 1 μm with respect to a distance of 20 μm in the longitudinal direction of the resonator. Semiconductor laser device. 6. The semiconductor according to claim 1, wherein the stripe structure has a stripe width at a laser end face on a front side from which light is output is wider than a width of a wide portion. Laser element. 7. The stripe structure according to claim 1, wherein the stripe width at the laser end face on both the front side and the opposite rear side from which light is output is larger than the width of the wide portion. The semiconductor laser device according to any one of the above. 8. The semiconductor device according to claim 1, wherein said semiconductor substrate is a GaAs substrate, said active layer has a GaInP / AlGaInP quantum well structure, and said cladding layer is an AlGaInP layer. The semiconductor laser device according to any one of the above. 9. The semiconductor device according to claim 1, wherein said semiconductor substrate is a GaAs substrate, said active layer has a GaInP single quantum well structure, and said cladding layer is an AlGaInP layer. The semiconductor laser device according to any one of the above. 10. The semiconductor substrate is a GaAs substrate,
8. The semiconductor laser device according to claim 1, wherein said active layer has a ZnCdSSe quantum well structure, and said cladding layer is a ZnMgSSe layer. 11. The semiconductor substrate is a GaN substrate formed on a sapphire substrate, and the active layer is formed of InGaN / Al.
It has a GaN quantum well structure, and the cladding layer is made of AlGa.
The semiconductor laser device according to claim 1, wherein the semiconductor laser device is an N layer. 12. An optical disk device comprising the semiconductor laser device according to claim 1 as a recording / reproducing light source.