WO1997041625A1

WO1997041625A1 - Semiconductor laser and method for manufacturing the same

Info

Publication number: WO1997041625A1
Application number: PCT/JP1997/001426
Authority: WO
Inventors: Isao Kidoguchi; Hideto Adachi; Yasuhito Kumabuchi; Masahiro Kitoh; Masahiro Kume
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 1996-04-26
Filing date: 1997-04-24
Publication date: 1997-11-06

Abstract

A semiconductor laser is provided with an active layer and a pair of clad layers formed so as to hold the active layer in between. The laser also has a stripe structure to form a carrier injecting area to the active layer in a stripe-like state toward a resonator. The stripe structure is constructed so that a relation W1∫W2 can be satisfied between the width W1 of the structure at the emitting-side end face of the resonator and the width W2 of the structure at the opposite end face of the resonator and, in additon, the width of the structure can be reduced to W1 from W2 in the direction of the resonator. The W2 is set at about 2 νm or wider.

Description

Description Semiconductor laser and method of manufacturing the same

Technical field

The present invention relates to a semiconductor laser used for an optical information processing device such as an optical disk, and more particularly to a semiconductor laser having a high COD level and a high optical output. Background art

An example of the configuration of a conventional semiconductor laser is disclosed in, for example, Japanese Patent Application Laid-Open No. Sho 62-73667. The configuration of this semiconductor laser 900 is schematically shown in FIG. In the conventional semiconductor laser 900 shown in FIG. 9, on an n-type GaAs substrate 901, an n-type AIG GaAs cladding layer 902, GaAs or A1 GaAs is formed. An active layer 903 made of s and a p-type A〗 GaAs cladding layer 904 are stacked in this order. On the p-type cladding layer 904, an n-type A 1 GaAs current blocking layer 905 having a larger bandgap than the p-type cladding layer 904 is formed. The current block layer 905 is provided with a stripe-shaped groove (also referred to as a "stripe structure") 905a. Further, the p-type A 1 GaAs buried layer 906 and the p-type GaAs contact layer 90 0 are covered so as to cover the current block layer 905 including the stripe-shaped groove 905 a. 7 is crystal-grown. A p-side electrode 909 is provided on the p-type contact layer 907, and an n-side electrode 908 is provided on the back surface of the n-side GaAs substrate 91.

In this semiconductor laser 900, a difference in effective refractive index is provided in a direction parallel to the surface of the active layer 903, and the refractive index of the waveguide region is higher than the refractive index outside the waveguide region. This constitutes a wave-shaped stripe laser. As a result, the confinement of light inside the waveguide region is enhanced, the differential quantum efficiency is high, and oscillation occurs in a single transverse mode. In general, semiconductor lasers that emit light in the visible light region, particularly in the red region in the wavelength range of about 630 nm to about 700 nm, use A] GaInP-based materials. A] Ga I _n p type semiconductor laser having an oscillation wavelength in such a visible light region, has application as a light source for devices such as an optical disc, recently been增its importance. When a semiconductor laser is used as a light source for a device such as an optical disk, a high light output is generally required. For example, when a semiconductor laser is used as a light source for a writable optical disk, an optical output of about 3 OmW or more is generally required.

And power, and, A 1 Ga I _n p type semiconductor laser, due to the nature of its constituent materials, Gwangsan force of C OD: limited by (Catastrophic Optical Daiiiag Ji Shun 0夺光Science injury). Force will the level of the optical output had been "COD level" produced by COD, ', COD levels of the above A 1 G a I n P-based material, comparison of about 1 MW cm ² ~ about 2 MW / cm ² Value and value.

Generally, COD is caused by heat generation near the resonant mirror of a semiconductor laser. In the configuration of the conventional semiconductor laser, COD is likely to be generated if a stable high output is to be obtained. When COD occurs, the cavity facet of the semiconductor laser is destroyed, and the desired operation of the semiconductor laser cannot be realized. Thus, it is difficult for conventional semiconductor lasers to achieve high output due to COD generation. Disclosure of the invention

A semiconductor laser according to an aspect of the present invention includes: an active layer made of an A 1 GaInP-based material; and a pair of cladding layers provided so as to sandwich the active layer. A stripe structure is further provided to make the carrier injection region for the layer stripe-shaped in the direction of the resonator, and the width of the stripe structure is determined by the value W1 at the emission-side end surface of the resonator and the emission-side end surface. At the end face opposite to W2 satisfies the relationship of Wl and W2, and is set to decrease from the value W2 to the value W1 with respect to the resonator direction, and the value W2 is about 2 μιη or more. In one embodiment, the active layer is made of an A1GaAs-based material.

Preferably, said value W2 is in the range from about 2 jum to about 5.

In one embodiment, the semiconductor device further includes a current block layer in which a stripe-shaped groove is formed, and the groove functions as the stripe-shaped structure.

Preferably, the effective refractive index difference in a direction parallel to the surface of the active layer is in the range of about 0.03 to about 0.02.

Preferably, said value W1 is about 2 m or less.

According to another aspect of the present invention, there is provided a semiconductor laser including an active layer, a pair of cladding layers provided so as to sandwich the active layer, and a stripe structure for injecting a carrier into the active layer in a stripe shape. Wherein the current blocking layer is made of a dielectric material, and the width of the stripe structure is opposite to the value W1 at the emission-side end face of the resonator and the width of the emission-side end face. The value W2 at the side end face satisfies the relationship of W1 and W2, and is set so as to decrease from the value W2 to the value W1 with respect to the resonator direction. 2 m or more.

The dielectric may be A〗 NO or SION.

Preferably, said value W2 is in the range from about 2 ^ m to about 5.

In one embodiment, a stripe-shaped groove is formed in the current block layer, and the groove functions as the stripe-shaped structure.

Preferably, the effective refractive index difference in a direction parallel to the surface of the active layer is in a range from about 0.003 to about 0.02.

Preferably, said value W1 is about 2 m or less.

The semiconductor laser according to another aspect of the further of the present invention includes a substrate, formed on the substrate,] I n _{_a} G _a - _a N and an active layer comprising a (0 <a <1), the active Upper and lower A 1 _b G a _b N cladding layers (0 <b <1) formed above and below A current blocking layer having an opening formed on the pad layer, and a third cladding layer formed so as to fill the opening, wherein the refractive index of the current blocking layer is The width of the opening is smaller than the refractive index of the upper cladding layer and smaller than the refractive index of the third cladding layer. Is set so that the value W2 at the opposite end face satisfies the relationship of W1 and W2, and decreases from the value W2 to the value W1 with respect to the resonator direction. The value W2 is about 2 or more.

Preferably, said value W2 is in the range from about 2 m to about 5.

Preferably, said value W1 is about 2 m or less.

The substrate may be a SiC substrate or a sapphire substrate.

Further, according to the present invention, a light source, a condensing optical system for condensing laser light emitted from the light source on a recording medium, and a photodetector for detecting laser light reflected by the recording medium An optical disc device is provided, wherein the light source is a semiconductor laser having the configuration as described above.

In one embodiment of the optical disk device, the semiconductor laser oscillates in a single mode when recording information on a recording medium, and a self-excited oscillation mode when reproducing information recorded on the recording medium. Works with

The photodetector may be arranged near the semiconductor laser.

The method of manufacturing a semiconductor laser according to the present invention includes a step of forming a stacked structure including at least a first clad layer, an active layer, a second clad layer, and a predetermined semiconductor layer on a substrate; Forming the second cladding layer and the predetermined semiconductor layer into a stripe shape, and forming an insulating film on the second cladding layer and the predetermined semiconductor layer processed into the stripe shape. And removing the predetermined semiconductor layer and the insulating film thereon. In the processing step for forming the stripe shape, the width of the stripe shape is such that the value W 1 at the emission-side end face of the resonator and the value W 2 at the end face opposite to the emission-side end face are W 1 < W2 is satisfied, and the width of the stripe shape is set to decrease from the value W2 to the value W1 with respect to the resonator direction, and the value W2 is set to about 2 μτη. As described above, a step of processing the second clad layer and the predetermined semiconductor layer may be included.

Preferably, said value W2 is in the range from about 2 m to about 5 m.

Preferably, said value W1 is about 2 or less.

A method of manufacturing a semiconductor laser according to another aspect of the present invention includes a step of forming a laminated structure including at least a first clad layer, an active layer, a second clad layer, and a first insulating film on a substrate. Processing the second cladding layer and the first insulating film into a stripe shape; and forming a stripe-shaped second cladding layer and the first insulating film on the second cladding layer and the first insulating film. Forming a second insulating film; and removing the first insulating film and the second insulating film thereon.

In the processing step for forming the stripe shape, the width of the stripe shape is such that the value W 1 at the emission-side end face of the resonator and the value W 2 at the end face opposite to the emission-side end face are W 1 <W 2. And the width of the stripe shape is set to decrease from the value W2 to the value W1 with respect to the resonator direction, and the value W2 is about 2 m or more. Processing the second cladding layer and the first insulating film.

Preferably, said value W2 is in the range from about 2 m to about 5 m.

Preferably, said value W 1 is about 2 μm or less.

Preferably, the effective refractive index difference in a direction parallel to the surface of the active layer is about 0.0.

Range from 0.3 to about 0.02. According to still another aspect of the present invention, there is provided a method of manufacturing a semiconductor laser, comprising: forming a laminated structure including at least a first cladding layer, an active layer, and a second cladding layer on a substrate; Forming a current blocking layer made of a dielectric on the cladding layer, and forming a stripe structure in the current blocking layer for injecting carriers into the active layer in a stripe shape. In the step of forming the stripe structure, the width of the stripe structure is such that the value W1 at the emission end face of the resonator and the value W2 at the end face opposite to the emission end face are W1 and W2. The width of the stripe structure is set to decrease from the value W2 to the value W1 with respect to the resonator direction, and the value W2 is about 2 m or more. Then, a process for processing the current block layer Including the.

Preferably, said value W2 is in the range from about 2 m to about 5 m.

Preferably, said value W1 is about 2 μιη or less.

The dielectric may be A 1 NO or SION.

In one embodiment, the step of forming the stripe structure includes a step of providing a stripe-shaped opening in the current block layer, and the opening functions as the stripe structure.

Accordingly, it is an object of the present invention to (1) provide a semiconductor laser having a high COD level and a high output, and (2) to provide a method for manufacturing such a semiconductor laser. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view schematically showing a configuration of an emission-side end face of a resonator in a semiconductor laser according to an embodiment of the present invention.

FIG. 2A, FIG. 2B, FIG. 2C, and FIG. FIG. 4 is a top perspective view schematically illustrating various changes in the width of the rip structure.

FIG. 3 is a diagram schematically showing a change in a waveguide mode due to a change in the width of a stripe structure in the semiconductor laser of the present invention.

FIG. 4 is a diagram showing the relationship between the width of the stripe structure and the threshold current density. FIG. 5 is a cross-sectional view schematically showing a configuration of an emission-side end face of a resonator in a semiconductor laser according to another embodiment of the present invention.

6A to 6C are cross-sectional views of the emission-side end face, schematically showing each step of the method for manufacturing the semiconductor laser of FIG.

FIG. 7 is a cross-sectional view schematically illustrating a configuration of an emission-side end face of a resonator in a semiconductor laser according to still another embodiment of the present invention.

8A to 8E are cross-sectional views of an emission-side end face, schematically illustrating steps of a method for manufacturing a semiconductor laser according to still another embodiment of the present invention.

FIG. 9 is a cross-sectional view schematically showing a configuration of an emission-side end face of a resonator in a semiconductor laser according to a conventional technique.

FIGS. 10A and 10B are perspective perspective views schematically showing various changes in the width of the stripe structure in a semiconductor laser according to the related art.

FIG. 11 is a diagram schematically showing a configuration of an optical disk device according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings.

(First Embodiment)

FIG. 1 is a cross-sectional view schematically showing a structure of a lateral mode control type semiconductor laser 100 according to the first embodiment of the present invention.

In the semiconductor laser 100, as shown in FIG. 1, on the n-GaAs substrate 101, an n-GaAs buffer layer 102 is used to form A1GaInP. Η-type cloud consisting of Layer 103, multiple quantum well active layer 104 including a well layer composed of GaInP, p-type first cladding layer 105 composed of A1GaInP, etching stop layer composed of p-type Ga1nP 106 are sequentially formed. Further thereon, a current block layer 107 made of n-type A] G a In P is formed, and the current block layer 10 Ί has a stripe-shaped opening 107 a (hereinafter referred to as “ Stripe structure 107a ”). On the etching stop layer 106 exposed through the current blocking layer 107 and the striped opening 107 a of the current blocking layer 107, a p-type second cladding made of A 1 G a In P is formed. Layer 108, further p-type GaAs cap layer 109, is formed. A p-side electrode 111 made of Cr / PtZAu is provided on the cap layer 109, and an n-side electrode 110 made of Au / Ge / Ni is provided on the back surface of the substrate 101. ing.

The composition and thickness of each of the above layers are as shown in Table 1 below. The active layer 104 has a multiple quantum well structure including three GaInP well layers and four A1GaInP barrier layers.

Table 1 Name Composition thickness cap layer 109 G a A s to about 3 mp type second clad layer _{_{108 (A 1 0. 6 G}} a 0. D) 0. 5 I n 0. 5 P about 0.9 m current block Layer 1 07 (A 1 _{0 7} Ga _{0 3} ) _{0 s} I n _{0 5} P About 0.

Etch stop layer 1 06 G a 0 ₅ I n _{0 5} P About 50

P-type first clad layer _{105 (A 10 6 G a 0.} 4) 0 5 I η 0., P about 0, 15 // m multi-quantum well active layer 104

Well layer Ga _{0 5 In} . . ₅ P about 50A barrier layer _{(A 1 o. 5 G a} 0. S). _s I n. . ₅ P about 50A n-type clad layer 103 (A] _{_{_{_{0. 7 G a 0. 3}}}} ) o. 5 I n 0 S P about lO m

2A to 2D show top perspective views of various configurations of the semiconductor laser 100. FIG. Specifically, in each of FIGS. 2A to 2D, the shape of the stripe structure 107a of the current block layer 107 when the semiconductor laser 100 is viewed from the side of the p-side electrode 111 is indicated by a dotted line. ing.

As can be seen from FIG. 2A, the individual chips of the semiconductor laser 100 typically have a resonator length of about 700 and a width perpendicular to the resonator length of about 300. The overall size of about 700 mx about 300 is the same in the configurations shown in FIGS. 2B to 2C.

In the configuration shown in Fig. 2A, the width of the stripe structure 107a is as strong as \ ¥ 1 == approximately 1. at the emission end face 10 ϋa, and continuously increases toward the opposite end face 100b. The width W2 of the stripe structure 107a at the opposite end face 100b is about 3.0. m. Thus, when the width W 1 of the stripe structure 107 a at the emission end face 100 a is reduced, the width of the laser light propagating inside the waveguide is reduced by the width of the stripe structure 107 a (W 1) Can be expanded. As a result, laser light is not concentrated near the emission side end face 100a of the semiconductor laser 100, and the COD level can be increased.

Further, with reference to FIG. 3, the manner in which the laser light can be expanded by setting the width of the stripe structure 107a as described above will be described.

FIG. 3 schematically shows how the waveguide mode changes in the semiconductor laser 100 due to a change in the width of the stripe structure 107a. Specifically, (I) in FIG. 3 shows a stripe structure near the end face 100b of the semiconductor laser 100; In the region where the width of 07a is wide), and (Π) in FIG. 3 is close to the emission end face 100a of the semiconductor laser 100, and the width of the stripe structure 107a is narrow. This is the waveguide mode in region Π.

According to Fig. 3, (I) shows a state in which the guided modes are densely packed in the thickness direction of the active layer, but (Π) shows a state in which such guided modes are not densely packed. The waveguide mode has a substantially circular shape. Thus, as the width of the stripe structure 107a becomes narrower as approaching the emission end face 100a of the resonator, the spot size of the laser beam of the semiconductor laser 100 becomes smaller in FIG. From (I) it can be seen that it spreads out as (Π). As described above, as the spot size of the laser beam increases as the width of the stripe structure 107a decreases, the emission side end face 100a of the semiconductor laser 100 is destroyed until a high output level is reached. Disappears.

In general, when the amount of current injected into the active layer of a semiconductor laser is increased, the optical output increases accordingly. In the semiconductor laser 100 of the present embodiment having the configuration shown in FIG. 1, an effective refractive index difference Δn-about 0.05 is provided in a direction parallel to the surface of the active layer 104. As a result, light is confined in the active layer 104 in a region corresponding to the stripe structure (opening) 107 a provided in the current blocking layer 107. Can be Further, the light emitted from the semiconductor laser 100 has a wavelength that is hardly absorbed by the current blocking layer 107 due to the difference in band gap. Therefore, in the semiconductor laser 100, the differential quantum efficiency is increased, and high output is realized. In the semiconductor laser 100, the width W2 of the stripe structure 107a in the vicinity of the end face 100b opposite to the emission end face 100a is preferably in the range of about 2 to about 5. Is set. The reason will be described with reference to FIG. FIG. 4 is a graph showing the relationship between the width of the stripe structure 101a in the semiconductor laser 100 (that is, the "stripe width") and the threshold current density.

When the width W2 of the stripe structure 107a is reduced and W2 is reduced to about 2 μm or less, the laser beam is emitted into the region of the active layer 104 immediately below the stripe structure 107a. You will not be trapped. As a result, the efficiency of laser oscillation decreases, and the threshold current density increases. As shown in FIG. 4, this increase in the threshold current density occurs particularly remarkably when the stripe width is about 1.5 m or less. On the other hand, when the stripe width is about 5 or more, kinks are likely to occur due to the presence of higher-order modes in addition to the first-order modes, which is not suitable for high output. Thus, the width W2 of the stripe structure 107a at the end face 100b opposite to the emission end face 100a of the semiconductor laser 100 is about 2 m to about 5 m. Is preferably set in the range.

Further, the effective refractive index difference in the direction parallel to the surface of the active layer 1 0 4 △ _n is about 0. 0 0 3 to about 0. 0 is preferably in the 2 range. Here, the effective refractive index difference Δn refers to a region of the active layer 104 into which a current is injected (specifically, a stripe structure (opening) 107 a of the current blocking layer 107). The difference between the effective refractive index in the horizontal direction (i.e., the stacking), and the effective refractive index in the area covered by the current blocking layer 107 and where no current is injected. In the direction parallel to the surface of each layer). When such an effective refractive index difference Δn is about 0.003 or less, the active layer 104 directly under the stripe structure 101 a is formed. The light cannot be sufficiently confined inside the region, the laser oscillation efficiency decreases, and the threshold current density increases. On the other hand, if the effective refractive index difference Δη is about 0.02 or more, the light confinement in the above region becomes too large (that is, light is excessively confined), and the COD level, which is the original purpose, is reduced. It is difficult to ascend.

The side electrodes 11 1 and 11 of the semiconductor laser 100 having the configuration described above

When a voltage is applied between the I-side electrodes 110, oscillation occurs in single transverse mode at an oscillation wavelength of about 650 nm. When measuring the current-voltage characteristics at this time, an output of about 10 OmW is obtained at room temperature. Even when the ambient temperature of the semiconductor laser 100 is changed from room temperature to about 80 ° C., the output does not reach the COD level until the output reaches about 6 OmW, and a stable output can be obtained.

In the configuration of FIG. 2A described above, the width of the stripe structure 107 a changes continuously between both end faces 100 a and 100 b of the semiconductor laser 100. I have. Alternatively, the semiconductor laser 100 may have a configuration as shown in FIGS. 2B to 2D. In the configuration shown in FIG. 2B, the width of the stripe structure 107a is constant in a region having a length of about 20 m from both end faces 100a and 100b of the semiconductor laser 100. In this way, by making the width of the strip structure 107 a constant in a predetermined area near the emission side end face 100 a and the opposite side end face 100 b, processing during resonator formation can be performed. This has the effect of increasing the allowable range of accuracy.

In the configuration of FIG. 2C, the stripe structure 107a is tapered in the region of about 100 in length on the side of the emission-side end face 100a, and its width is continuously changed. On the other hand, except for the tapered region (region closer to the opposite end face 100b), the width of the stripe structure 107a is constant at about 3 μπι. The configuration shown in FIG. 2C has an effect of reducing the scattering loss of the guided light due to the change in the width of the stripe structure 107a.

Further, in the configuration of FIG. 2D, the strip structure 107 a is formed in a region of about 100 m in length on the side of the emission-side end face 100 a as in FIG. 2C. Make it pat The width is continuously changed. However, unlike the configuration of FIG. 2C, the taper shape is curved. On the other hand, in the area other than the tapered area (area closer to the opposite end face 100b), the width of the stripe structure 107a is constant at about 3 m. In the configuration shown in FIG. 2D, by forming the taper shape of the striped structure 107a into a curved shape, a higher output semiconductor laser with less waveguide loss of laser light is obtained. It becomes possible.

According to a striped structure which functions for the purpose of forming a waveguide structure inside a resonator, the configuration of a semiconductor laser in which the width of a part of the region is tapered in the horizontal direction is as follows. The one shown in Figure 1OA or Figure 10B has been proposed.

FIG. 1OA is a perspective view schematically showing a configuration of a semiconductor laser 110 disclosed in Appl. Phys. Lett., Vol. 64, pp. 539-541 (1994). Specifically, the semiconductor laser 10010 is provided with a stripe structure 11013 filled with a p-type doped layer 11012 on the n-type substrate 101. Is an InGaAsP-based semiconductor laser that oscillates at a wavelength of about 1.55 m, and the stripe structure inside one laser resonator is a region with a uniform width. 1013 b and a region 1013 a of which width changes. The uniform width of the stripe structure 101 in the region 103 b is about 2.0 m. On the other hand, in the region 103a, the width of the stripe structure 103 is gradually reduced from about 2.0; / m to about 0.7m. On the other hand, FIG. 10B is a perspective view schematically showing a configuration of a semiconductor laser 120 disclosed in Electron Lett., Vol. 31, No. 17, pp. 1439/1440 (1995). is there. Specifically, the semiconductor laser 102 is an InGaAsP-based laser that oscillates at a wavelength of about 1. μm, and has a stripe structure (strained multiple quantum well active layer). Part of the region 102 is formed to have a tapered shape. The width of the striped structure 1021 is constant outside of the tapered region 1022, but in the tapered region 1022, the stripe structure 1ϋ2 1 Is gradually narrowing from about 1. ◦ "m to about 0.6 μπι. As described above, also in the conventional semiconductor lasers 1010 and 10020, a configuration is provided in which the stripe structure includes a region having a tapered shape. However, each of these conventional semiconductor lasers 11010 and 10020 is a laser having an oscillation wavelength of about 1 m or more. In such a long-wavelength semiconductor laser, due to the properties of the constituent materials, the effective refractive index difference in a direction (horizontal direction) parallel to the surface of each stacked layer is only about 0.1. For this reason, in the semiconductor lasers 1010 and 10020, as in the present invention, a configuration is formed in which the width W2 at the end face opposite to the emission end facet of the stripe structure is about 2 / m or more. Then, laser oscillation in the basic transverse mode becomes difficult.

Further, the purpose of providing a tapered region in the stripe structure with these semiconductor lasers 110 and 102 is to increase the spot size of the laser light and to increase the size of the semiconductor lasers. This is to couple outgoing light to an optical fiber without using a lens. In any case, it is not intended to increase the COD level as in the present invention.

As described above, according to the present invention, the width of the stripe structure at the exit side end face of the resonator is reduced to about 2 m or less, so that light guided in the resonator is more lateral than the stripe structure. It has a configuration that spreads in the direction. As a result, there is no light concentration at the emission-side end face, the COD level is increased, and a highly reliable and high-output semiconductor laser can be obtained.

In addition, the width of the stripe structure on the end face opposite to the end face on the emission side of the resonator should be approximately

By setting the length to 2 m or more, oscillation in the fundamental transverse mode is possible without increasing the waveguide loss or the threshold current density.

(Second embodiment)

The semiconductor laser 1 0 0 in the first embodiment is A 1 G a I n P-based laser, the semiconductor laser 2 0 0 in this _{_{embodiment, A 1 X G a y I}} n Bok _xy N (0x≤l and 0≤y≤l) laser. In the semiconductor laser 200, like the semiconductor laser 100, the stripe structure has a shape that is narrow on the emission side end face and wide on the opposite side end face as described with reference to FIGS. 2A to 2D. Yes.

FIG. 5 is a cross-sectional view schematically illustrating a configuration of the emission-side end face of the semiconductor laser 200.

In the semiconductor laser 200, an n-type A] N buffer layer 203 (having a thickness of about 100 μm) is formed on a π-type nm), n type A] _X G a have _X n clad layer 204 (thickness: about 1 m>,及beauty I n _{_Z} G a _Z n active layer 205 (thickness: about 50 nm) is formed.

In A 1 _X Ga to _X N constituting the n-type cladding layer 204, the energy gap of AIG a N increases and the refractive index decreases as the composition ratio x of A 1 N increases. In determining the composition ratios X and z, first, when a desired oscillation wavelength is determined, the composition ratio z of InN of the active layer 205 is determined accordingly, and the A 1 of the n-type cladding layer 204 is determined accordingly. The value of the composition ratio x of N is determined. For example, when the oscillation wavelength is about 410 nm (purple), z = about 0.15, and x uses a value in the range of about 0.1 to about 0.2.

The active layer 205 may have a multiple quantum well structure instead of being constituted by a single layer. In that case, for example, five layers of In. . _s G a. . ₉₅ N well Toso and six layers _{_{_{I n 0. 2 G a 0}}} . Using ₈ N barrier layer. In this case, a multiple quantum well structure can be grown only by changing the composition of In between the barrier layer and the well layer, and there is no need to change the growth temperature. Therefore, the growth of the multiple quantum well structure can be easily performed, and the In composition can be strictly controlled.

Above the active layer 205, p-type A 1 _y G a Bok _y N first clad layer 206 (thickness of about 0. 2 m), the n-type G a N etch stop layer 212, and n-type A 1 _u G a _{U U A} current blocking layer (gouge layer) 207 is formed. In the current block layer 207, Stripe-shaped openings (stripe structures) 207a reaching the GaN etching stopper layer 212 with a width of about 111 to about 10 m are formed. The thickness of the n-type current block layer 207 is, for example, about 0.7 m. The current is blocked by the n-type current blocking layer 207 and flows only through the opening 207 a, and is injected into only the region of the active layer 205 directly below the opening 207 a.

Over the opening 2 0 7 a of the inner and n-type鼋流Bed-locking layer 2 0 7, p-type A 1 _v G a have _V N second clad layer 2 0 8 are formed. The p-type second cladding layer 208 has a thickness force of about 0.5 m on the current blocking layer 207. Here, by setting the composition ratio of each related layer so that u> y and u> v, the refractive index of the current block layer 207 becomes the p-type first cladding layer 206 and p It becomes smaller than the refractive index of the mold second cladding layer 208. As a result, light is confined in a direction parallel to the surface of the active layer 205, optical waveguide is realized by the effective refractive index difference of the active layer 205, and laser light without any difference is obtained.

The effective refractive index difference of the active layer 205 is the refractive index between the area of the active layer 205 immediately below the opening 207a and the area covered by the current blocking layer 207. Make a difference. The effective refractive index difference to be set is determined in consideration of the width of the opening 207a. For example, when the width of the opening 207a is about 1 m to about 8 m as in the semiconductor laser 200 of the present embodiment, the effective refractive index difference of the active layer 205 is about Preferably, it is in the range of 0.003 to about 0.02. The reason is that if the effective refractive index difference of the active layer 205 is too large, a higher-order mode will be established, while if the effective refractive index difference is too small, the propagating light will spread.

On the p-type second cladding layer 208, a p-type GaN cap layer 209 (about 0.5 m thick) and an impurity concentration of about 1 × ^{10 18} cm ³ or more are provided. A _p- type GaN contact layer 210 (having a thickness of about 0.5 ^ τη) having the following structure is formed.The upper surface of the ρ-type contact layer 210 and the back surface of the substrate 202 are A ρ-side electrode 211 and an η-side electrode 201 are formed, respectively. The electrode material of the η-side electrode 201 is typically T i and A u The electrode material of the p-side electrode 211 is typically Ni and An.

The impurity doped in each layer having the n-type conductivity is typically Si, and the impurity doped in each layer having the p-type conductivity is typically Mg. The width of the opening 207a and the refractive index difference between the p-type cladding layers 206 and 208 and the current blocking layer 207 determine the intensity distribution of the light confined in the active layer 205. Therefore, these parameters must be set to appropriate values. In the semiconductor laser 200 of the present embodiment, the width of the opening 207a is typically about 2 m. Regarding the composition ratio of each layer that determines the refractive index difference between the p-type cladding layers 206 and 208 and the current block layer 207, the A 1 N composition ratio u of the current block layer 207 is typically Is u = 0.25, and the A〗 N composition ratios y and V of the p-type cladding layers 206 and 208 are typically 0.15 like the AIN composition ratio X of the n-type cladding layer 204. It is.

By the above, p-type first and second clad layers 206 and 208 (both _{_{_{A 1 0 15 G a 0. 8S}}} N layer) and the current blocking layer _{_{207 (A 1 0. 25 G}} a 0. 7S N layer) Due to the difference in refractive index between the two, laser light in a direction parallel to the surface of the active layer 205 is confined inside the active layer 205, and oscillates in a single mode. As a result, a GaN-based semiconductor laser that provides a laser beam having a low threshold value, a low current density, and no aberration is realized.

In the semiconductor laser 200 of the present embodiment described above, the substrate 202 is formed of the S i C inclined substrate inclined about 3.5 degrees from the (0001) direction to the [111-120] direction. This is to ensure good flatness of the surface of the deposited layer when a semiconductor deposited layer is formed on the SiC substrate (particularly when depositing an A1GaN mixed crystal layer). [0001] The flatness of the crystal surface of the deposited layer is better when an inclined substrate is used than when a just substrate is used. In particular, when the angle of inclination is set in the range of about 3 degrees to about 12 degrees, extremely good flatness of the crystal surface of the deposited layer can be obtained. The application of the present invention is not limited to a semiconductor laser using an inclined substrate, but is also applicable to a configuration using a just substrate such as a (001) just substrate. is there.

6A to 6C are cross-sectional views schematically showing each step of the method of manufacturing the semiconductor laser 200 of the present embodiment described above. 6A to 6, the same components as those shown in FIG. 5 are denoted by the same reference numerals, and detailed description thereof may be omitted here.

More specifically, as shown in FIG. 6A, each layer from an n-type A 1 N buffer layer 203 to an n-type current block layer 207 is formed on an n-type SiC substrate 202. Is grown using the MOVPE method. After that, a photomask (not shown) is formed on the n-type current block layer 207. The photomask has a stripe-shaped opening in which the width of a portion corresponding to the emission-side end surface of the semiconductor laser to be formed is smaller than the width of a portion corresponding to the opposite end surface. Then, using the photomask, the current blocking layer 207 is removed by etching until the etching stop layer 221 is exposed as shown in FIG. 6B, and the current blocking layer 207 is striped on the current blocking layer 207. Opening (stripe structure) 207a is formed.

Next, the layers from the p-type second cladding layer 208 to the p-type contact layer 210 are sequentially grown again by the MOVPPE method, as shown in FIG. 6C.

Finally, a p-side electrode 211 is formed on the ρ-type contact layer 210, and an η-side electrode 201 is formed on the back surface of the n-type SίC substrate 202, thereby forming a semiconductor. Laser 200 is completed.

(Third embodiment)

Next, a semiconductor laser 300 according to a third embodiment of the present invention will be described with reference to FIG.

In the semiconductor laser 3 0 0, the A 1 ₂ 0 ₃ (sapphire) substrate as the substrate 3 0 2 A GaN layer (about 100 nm thick) is used as the buffer layer 303 formed on the substrate 302. On the buffer layer 303, the same laminated structure as the semiconductor laser 200 in the second embodiment, that is, the n-type cladding layer 304, the active layer 305, and the p-type first cladding Layer 306, current blocking layer 307 having stripe-shaped openings (stripe structure) 307a, p-type second cladding layer 308, p-type cap layer 309, and p The mold contact layers are formed in the order of 310 layers. In these stacked structures, the layers corresponding to the respective layers included in the semiconductor laser 200 described above are denoted by similar reference numerals, and detailed description thereof will be omitted here.

The semiconductor laser 300 is different from the semiconductor laser 200 in that the n-side electrode 301 is formed. Specifically, in the semiconductor laser 300, the thickness of the n-type cladding layer 304 is increased to about 2 m, and an opening (striped structure) 307a is formed in the current block layer 307. The semiconductor layered structure corresponding to the region where is not present is removed by etching until the thickness of the n-type cladding layer 304 becomes about 1 // m. An n-side electrode 301 is formed on the surface of the n-type cladding layer 304 exposed by this etching. Note that the P-side electrode 311 is formed on the upper surface of the p-type contact layer 310 as in the case of the semiconductor laser 200.

In the semiconductor laser 300 as well, the effective refractive index difference in the direction parallel to the surface of the active layer 300 is about 0.003 to about 0.02 for the same reason as in the previous embodiments. Is preferably set in the range. Further, as described above with reference to FIGS. 2A to 2D, the stripe-shaped opening (stripe structure) 307 a of the current blocking layer 307 has a narrow width at the emission-side end face. The width at the opposite end face is wide. '

The semiconductor laser 300 having the above configuration has a low threshold current density and an optical output with a good linearity with respect to the driving current in a wide optical output range up to a level of about 2 OmW or more. Characteristics are obtained. In the semiconductor lasers 100 to 300 of the first to third embodiments described above, the active layer may have another structure instead of the structure described above. For example, instead of an active layer having a quantum well structure, an active layer consisting of a single InGaN layer having a thickness of about 50 nm can be provided. Alternatively, using an active layer having a single quantum well structure in which an InGaN layer having a thickness of about 10 nm is sandwiched between a pair of A1Gan layers having a thickness of about 50 nm, Value current density can be further reduced.

When the active layer has a multiple quantum well structure, a multiple quantum well structure in which an AIG aN layer having a thickness of about 10 nm is provided between each of two or more InGaN layers may be used. .

Furthermore, the p-type GaN contact, which is in contact with the p-side electrode, has a p-type impurity concentration of typically 1 × ^{10 18} cm ³ or more in order to form a low-resistance homogenous contact. And Alternatively, the G a small energy formic Yap than N I _n G a N be used as a constituent material of the contactor coat layer, it is possible to further reduce the contactor Bok resistance. However, also in this case, in order to realize a low contact resistance, it is preferable to set the p-type impurity concentration to about 1 × ^{10 18} Z _C m ³ or more.

Further, the p-side electrode itself is preferably made of a material having a large work function in order to reduce the contact resistance. Specifically, the p-side electrode may be formed using Pt.

As described above, in the semiconductor laser of the present invention, the injected current is narrowed in a stripe shape and supplied to the active layer by using the current block layer having the stripe-shaped opening (striped structure). Thereby, the efficiency of laser oscillation is improved and a low threshold current can be obtained. At the same time, by using the effective refractive index distribution in the direction parallel to the surface of the active layer to confine the laser beam in the above-mentioned direction, laser beam without aberration can be obtained. As a result, the semiconductor laser of the present invention described above can be used as a light source for a high-density optical disk. (Fourth embodiment)

The first to third embodiments described so far are of a so-called “inner stripe type” in which a strip-shaped opening (that is, a groove-shaped stripe structure) is formed in the current blocking layer. It has a structure. On the other hand, the semiconductor laser 400 of the present embodiment described below is a so-called “ridge stripe type” semiconductor laser having a ridge-shaped stripe structure (also simply referred to as “ridge”). In such a ridge stripe type structure, the ridge has a shape that is narrow at the emission end surface and wide at the opposite end surface, as described above with reference to FIGS. 2A to 2D. I have.

A method for manufacturing the semiconductor laser 400 of the present embodiment will be described below with reference to FIGS. 8A to 8E. 8A to 8E are cross-sectional views schematically showing each step of the method for manufacturing the semiconductor laser 400 of the present embodiment.

First, as shown in FIG. 8 A, on the n-type G a A s the substrate 401, and more MOVP E method, n-type G a A s carbonochloridate Ffa layer 402, n-type (A l _{₀ 7} G a ₀ _{_{_{. 3) 0. 5 I n}}} 0 5 P clad layer 403, the active layer 404, p-type _{_{(A 1 0. 7 G a}} 0. 3) 0. 5 I n 0. 5 P clad layer 405, p-type the _{_{_{G a 0. 5 I n 0}}} 5 P layer 406, p-type Ga a s contactor coat layer 407 and a] a s layer 408, are laminated in this order.

The active layer 404 has, for example, a multiple quantum well structure. In this case, specifically, G a thickness of about _{_{50 A 0. S I n 0}} . 5 P well layer and the thickness of about 50 people _{_{(A 1 0. 5 G a}} 0 5) 0. 5 I π _0. ₅ ρ by combining the barrier layer to form a multi-quantum well structure, also, eta type clad layer 403 and the ρ-type clad layer 405 together, as previously described (a 1 _{0 7} G and _{_{a 0 3) 0. 5 I n}} 0 5 P layer.

Next, the Te Pa like S i 0 ₂ mask layer 409, you formed on the A l A s layer 408. This SiO ₂ mask layer 409 has a width of approximately 2 at a position corresponding to the emission-side end surface of the semiconductor laser to be formed, and has a width of approximately 4 μπι at a position corresponding to the opposite-side end surface. Then, dry etching is performed using this mask layer 409. The A 1 A s layer 408, the p-type GaAs contact layer 407, and the p-type G a _{0 ε} I n _{0 in the} area not covered by the mask layer 409 _The SP layer 406 and the P-type AlGaInP cladding layer 405 are partially removed to form a ridge 407a as shown in FIG. 8B.

Next, as shown in FIG. 8 C, by ECR sputtering, on the p-type A] G a I n P click rats de layer 4 0 5 and S I_〇 ₂ mask layer 4 0 9, A 1 N layer Deposit 4 10. Subsequently, as shown in FIG. 8 D, by a lift-off method, the ridge 4 0 7 A 1 N layer 4 1 0 contained in a, S i 〇 ₂ mask layer 4 0 9, and A 1 A s layer 4 08 is removed to expose the p-type contact layer 407 on the top surface of the ridge 407a.

Thereafter, the p-side electrode 4 is placed on the p-type GaAs contact layer 407 included in the ridge 407a and the A1N layer 410 located on both sides of the ridge 407a. Form 1 2 An n-side electrode 411 is formed on the back surface of the n-type GaAs substrate 401. As a result, as shown in FIG. 8E, the semiconductor laser 400 is completed.

In the semiconductor laser 400 having the above configuration, since the A 1 N layer 410 is an insulating layer, it functions as a current blocking layer. Further, since the A 1 N layer 410 has a lower refractive index than the n-type cladding layer 400 and the p-type cladding layer 405, it is parallel to the surface of the active layer 404. The effective refractive index difference in different directions. Further, the A 1 N layer 410 has a large band gap and hardly absorbs the laser light emitted from the active layer 404. Therefore, the differentiation efficiency can be increased and a high level of light output can be realized. In addition, since A1N is a material with excellent heat dissipation, it enables laser oscillation at high temperatures.

Even in the semiconductor laser 400 described above, the ridge 407a is formed to have a narrow width at the end face on the emission side, and therefore, as described above with reference to FIG. The spot size of the light spreads at the end face on the emission side, and an increase in the COD level can be achieved. (Fifth embodiment)

Next, as a fifth embodiment of the present invention, an optical disk device 500 configured using a semiconductor laser formed according to the present invention will be described with reference to FIG. Specifically, in the optical disc device 500 of the present embodiment, the semiconductor laser described in each of the above embodiments is used as the light source 501. The light source 501 emits a laser beam 502 having a wavelength of about 650 nm. This laser beam 502 is collimated by a collimator lens 503 and then split into three beams by a diffraction grating 504 (however, in FIG. 11, a single beam is used for simplicity). Shown as a beam). Thereafter, the light beam passes through a half prism 505 that selectively transmits or reflects only a specific component of the laser light, and is condensed by a condenser lens 506, and the optical disk (recording medium) 5 Connect a spot about 1 m in diameter on 07. As the optical disk 507, a rewritable disk can be used in addition to a read-only disk.

The reflected light from the optical disk 507 passes through the condenser lens 506 again, is reflected by the half prism 505, and travels to the light receiving lens 508. Then, the light passes through the light receiving lens 508 and the cylindrical force sensor 509 and enters the light receiving element 510. The light receiving element 5100 has a plurality of divided photodiodes, and converts a detected optical signal into an electric signal to generate an information reproduction signal, a tracking signal, and a focus error signal. .

To further describe the generation of the tracking signal and the focus error signal, the light beam spot on the optical disk 507 can be obtained by using the divided three beams at the time of the light detection in the light receiving element (photodiode) 501. Detects deviation (tracking error) of the disk in the disk radial direction. In addition, the cylindrical lens 509 detects a displacement (focusing error) of the focal point of the light beam spot in a direction perpendicular to the surface of the optical disk 507. Based on these detected deviations (tracking error and focusing error), the tracking signal and focusing error are detected. An occasella signal is generated. Then, the position of the optical beam spot on the optical disk 507 is finely adjusted by the drive system 511 based on the generated tracking signal and focus error signal, and the deviation is corrected. Specifically, for example, the position is corrected by finely adjusting the position of the condenser lens 506 with the drive system 511.

As described above, the optical disk device 503 shown in FIG. 11 includes a semiconductor laser 501 functioning as a light source and a condensing optic for guiding the laser beam 502 from the semiconductor laser 501 to the optical disk 507. And an optical detector 510 for detecting light reflected from the optical disk 507, and reads (reproduces) information signals recorded on the optical disk 507. In addition, writing (recording) to the optical disk 507 can be performed by increasing the optical output from the semiconductor laser 501. That is, it is possible to realize an optical disk device 500 having a simple configuration and excellent characteristics, which can perform both reading and writing functions while using one semiconductor laser 501 as a light source. .

In particular, when the semiconductor laser of the present invention described in each of the above embodiments is used as the semiconductor laser 501 as a light source, the oscillation wavelength is about 650 nm and about 5 OmW. Output laser light can be used. Therefore, information can be stably written on the optical disk 507.

On the other hand, in reproducing information recorded on the optical disk 507, it is not necessary to operate the semiconductor laser 501 at high output. Specifically, the semiconductor laser 501 is adjusted to operate at a low output of about 5 mW. Further, by driving the semiconductor laser 501 in a self-sustained pulsation mode using, for example, a high frequency superposition method, noise is reduced even in a state where return light from the optical disk 507 exists. In addition, reproduction processing with low distortion can be realized.

As described above, by using the semiconductor laser of the present invention as a light source of an optical disc device, a wavelength of about 65 nm can be obtained by using one semiconductor laser (light source) 501. Thus, high-density information recording and reproduction can be realized. This realizes a high-performance optical disk device 500 with a simple configuration.

In a configuration in which the semiconductor laser (light source) 501 and the light receiving element 501 are arranged close to each other, the semiconductor laser (light source) 501 and the light receiving element 501 are integrated. This makes it possible to further reduce the size of the optical disk device 500. Industrial applicability

As described above, according to the semiconductor laser of the present invention, the width of the strip structure at the emission end face of the resonator is reduced to about 2 or less, so that light guided through the resonator has a stripe structure. Spreads sideways from. As a result, the light concentration at the emission-side end face disappears, the COD level increases, and a high output can be obtained. Also, by setting the width of the stripe structure at about 2 πι or more, preferably at about 2 πι to about 5 m at the resonator end face opposite to the emission end facet, the waveguide loss and the threshold are increased. The increase in the current density is suppressed, and oscillation in the fundamental transverse mode is enabled. Thus, a highly reliable semiconductor laser can be obtained. In addition, an effective refractive index difference is provided in a direction parallel to the surface of the active layer so that the refractive index in the region inside the stripe structure is higher than the refractive index in the region outside the stripe structure. The composition ratio of the constituent materials of the related layers is set appropriately so that the current block layer hardly absorbs. As a result, the differential quantum efficiency is high, and oscillation is possible even in a single transverse mode.

Here, what defines the single transverse mode is the value of the width (wider width) W2 of the stripe structure at the end face of the resonator opposite to the output end face. Specifically, by setting the width W2 to about 2 to about 5 m, a semiconductor laser free of kink during operation can be obtained.

As described above, in the semiconductor laser of the present invention, the generation of COD is suppressed, Light output can be obtained.

Furthermore, in the optical disk device of the present invention, by using the semiconductor laser of the present invention as a semiconductor laser as a light source, a laser beam having a wavelength of about 650 rim and a high output of about 50 mW can be produced. Available. Therefore, information can be stably written on the optical disc. On the other hand, in reproducing information recorded on an optical disk, it is not necessary to operate a semiconductor laser at a high output. Specifically, the semiconductor laser is adjusted to operate at a low output of about 5 mW. Further, by driving the semiconductor laser in a self-excited oscillation mode using, for example, a high-frequency superposition method, it is possible to realize a reproduction process with low noise and low distortion even in the presence of return light from the optical disk.

In addition, by using the semiconductor laser of the present invention as the light source of the optical disk drive S, it is possible to record and reproduce high-density information at a wavelength of about 600 nm using one semiconductor laser (light source). Is done. This realizes a high-performance optical disk device with a simple configuration.

Claims

The scope of the claims

1. an active layer made of A 1 G a In P material;

A pair of cladding layers provided so as to sandwich the active layer,

With

A stripe structure for forming a carrier injection region for the active layer in a stripe shape with respect to a resonator direction is further provided;

The width of the stripe structure is such that the value W1 at the emission-side end face of the resonator and the value W2 at the end face opposite to the emission-side end face satisfy a relationship of W1 and W2, and the width with respect to the resonator direction. A semiconductor laser configured to decrease from the value W2 to the value W1, wherein the value W2 is about 2 / m or more.

2. The semiconductor laser according to claim 1, wherein the active layer is made of an A1GaAs-based material.

3. The semiconductor laser according to claim 1, wherein said value W2 is in a range from about 2 to about 5 m.

4. The semiconductor laser according to claim 1, further comprising a current block layer in which a stripe-shaped groove is formed, wherein the groove functions as the stripe-shaped structure.

5. The semiconductor laser according to claim 1, wherein an effective refractive index difference in a direction parallel to a surface of the active layer is in a range from about 0.003 to about 0.02.

6. The semiconductor laser according to claim 1, wherein the value W1 is about 2 or less.

7. an active layer;

A pair of cladding layers provided so as to sandwich the active layer,

A current block layer having a stripe structure for injecting a carrier into the active layer in a strip shape;

With

The current block layer is composed of a dielectric,

The width of the stripe structure is such that the value W1 at the emission-side end face of the resonator and the value W2 at the end face opposite to the emission-side end face satisfy a relationship of W1 and W2, and the width with respect to the resonator direction. A semiconductor laser configured to decrease from the value W2 to the value W1, wherein the value W2 is about 2 m or more.

8. The semiconductor laser according to claim 7, wherein the dielectric is A 1 NO or SION.

9. The semiconductor laser according to claim 7, wherein said value W2 is in a range from about 2 m to about 5 m.

10. The semiconductor laser according to claim 7, wherein a stripe-shaped groove is formed in the current block layer, and the groove functions as the stripe-shaped structure.

1 1. The semiconductor laser according to claim 7, wherein an effective refractive index difference in a direction parallel to a surface of the active layer is in a range of about 0.003 to about 0.02.

12. The semiconductor laser according to claim 7, wherein the value W1 is about 2 m or less.

13. With the substrate

Formed on the _{_{substrate, I n a G aia N (}} 0 <a <1) active layer and an upper formed above and below the active layer and the lower A 1 _b G a L bN clad layer comprising (0 <b <1)

A current blocking layer formed on the upper cladding layer and having an opening; and a third cladding layer formed to fill the opening.

With

A refractive index of the current blocking layer is smaller than a refractive index of the upper cladding layer and smaller than a refractive index of the third cladding layer;

The width of the opening is such that the value W1 at the emission-side end face of the resonator and the value W2 at the end face opposite to the emission-side end face satisfy the relationship of Wl <W2, and the width in the direction of the resonator. A semiconductor laser configured to decrease from the value W2 to the value W1, wherein the value W2 is about 2 m or more.

14. The semiconductor laser of claim 13, wherein said value W2 is in a range from about 2 m to about 5 in.

15. The semiconductor laser according to claim 13, wherein an effective refractive index difference in a direction parallel to a surface of the active layer is in a range from about 0.003 to about 0.02.

16. The semiconductor laser according to claim 13, wherein said value W1 is about 2 μm or less.

17. The semiconductor laser according to claim 13, wherein the substrate is a SiC substrate or a sapphire substrate.

1 8. Light source and

A focusing optical system that focuses the laser light emitted from the light source on a recording medium; a photodetector that detects the laser light reflected by the recording medium;

With

An optical disc device, wherein the light source is the semiconductor laser according to claim 1.

19. The semiconductor laser oscillates in a single mode when information is recorded on the recording medium, and operates in a self-excited oscillation mode when reproducing information recorded on the recording medium. 18. The optical disk device according to item 8.

20. The optical disc device according to claim 18, wherein the photodetector is arranged near the semiconductor laser.

2 1. Light source and

A focusing optical system that focuses laser light emitted from the light source on a recording medium, a photodetector that detects the laser light reflected by the recording medium,

With

An optical disc device, wherein the light source is the semiconductor laser according to claim 7.

22. The semiconductor laser oscillates in a single mode when information is recorded on the recording medium, and operates in a self-excited oscillation mode when reproducing information recorded on the recording medium. 2. The optical disc device according to 1.

23. The optical disc device according to claim 21, wherein the photodetector is arranged near the semiconductor laser.

2 4. Light source and

A condensing optical system for condensing laser light emitted from the light source on a recording medium,

A photodetector for detecting a laser beam reflected by the recording medium,

With

An optical disk device, wherein the light source is the semiconductor laser according to claim 13.

25. The semiconductor laser oscillates in a single mode when information is recorded on the recording medium, and operates in an S excitation mode when reproducing information recorded on the recording medium. 24. The optical disk device according to item 4.

26. The optical disk device according to claim 24, wherein the photodetector is arranged near the semiconductor laser.

27. A step of forming a stacked structure including at least a first clad layer, an active layer, a second clad layer, and a predetermined semiconductor layer on the substrate;

Processing the second cladding layer and the predetermined semiconductor layer into a stripe shape; and forming an insulating film on the second cladding layer and the predetermined semiconductor layer processed into the stripe shape. Forming a;

Removing the predetermined semiconductor layer and the insulating film thereon;

A method for manufacturing a semiconductor laser, comprising:

28. In the processing step for forming the stripe shape, the width of the stripe shape is such that the value W 1 at the emission end face of the resonator and the value W 2 at the end face opposite to the emission end face are W 1 And the width of the stripe shape is set to decrease from the value W2 to the value W1 with respect to the resonator direction, and the value W2 is set to about 2 m. As described above, the second clad layer and the predetermined semiconductor layer are processed. 28. The method of manufacturing a semiconductor laser according to claim 27, further comprising the step of:

29. The method of manufacturing a semiconductor laser according to claim 28, wherein the value W2 is in a range of about 2 μπ to about 5 m.

30. The method for manufacturing a semiconductor laser according to claim 28, wherein the value W1 is about 2 / ^ m or less.

31. The method for manufacturing a semiconductor laser according to claim 27, wherein an effective refractive index difference in a direction parallel to a surface of the active layer is in a range of about 0.003 to about 0.02.

32. a step of forming a laminated structure including at least a first clad layer, an active layer, a second clad layer, and a first insulating film on the substrate;

Processing the second cladding layer and the first insulating film into a stripe shape; and forming a second Forming an insulating film of

Removing the first insulating film and the second insulating film thereon;

A method for manufacturing a semiconductor laser, comprising:

33. In the processing step for forming the stripe shape, the width of the stripe shape is such that the value W 1 at the emission end face of the resonator and the value W 2 at the end face opposite to the emission end face are W 1 W2, and the width of the stripe shape is set to decrease from the value W2 to the value W1 with respect to the resonator direction, and the value W2 is set to about 2 μm. 33. The method for manufacturing a semiconductor laser according to claim 32, comprising a step of processing the second cladding layer and the first insulating film so that the length is at least m.

34. The method of manufacturing a semiconductor laser according to claim 33, wherein the value W2 is in a range of about 2 m to about 5.

35. The method for manufacturing a semiconductor laser according to claim 33, wherein the value W1 is about 2 m or less.

36. The method for manufacturing a semiconductor laser according to claim 32, wherein an effective refractive index difference in a direction parallel to a surface of the active layer is in a range of about 0.003 to about 0.02.

37. Forming a laminated structure including at least a first cladding layer, an active layer, and a second cladding layer on a substrate;

Forming a current block layer made of a dielectric on the second cladding layer; and forming a stripe structure in the current block layer for injecting a carrier into the active layer in a stripe shape. When,

And

In the step of forming the stripe structure, the width of the stripe structure is such that the value W1 at the emission end face of the resonator and the value W2 at the end face opposite to the emission end face are Wl <W2. Is satisfied, and the width of the stripe structure is reduced from the value W2 to the value W] with respect to the resonator direction, and the value W2 is about 2 m or more. Thus, a method for manufacturing a semiconductor laser including a step of processing the current block layer.

38. The method of manufacturing a semiconductor laser according to claim 37, wherein the value W2 is in a range of about 2 to about 5.

39. The method of manufacturing a semiconductor laser according to claim 37, wherein the value Wl is about 2 or less.

40. The method according to claim 37, wherein an effective refractive index difference in a direction parallel to a surface of the active layer is in a range of about 0.003 to about 0.02.

4 1. The method for manufacturing a semiconductor laser according to claim 37, wherein the dielectric is A 1 NO or SION.

42. The method according to claim 37, wherein the step of forming the stripe structure includes a step of providing a stripe-shaped opening in the current block layer, and the opening functions as the stripe structure.