JP2001148536A - Semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actuate a semiconductor laser device to oscillate in the fundamental transverse mode, over a power range from low power to high power, and obtain high reliability. SOLUTION: After laminating a GaAs buffer layer 32 on a GaAs substrate 31, a GaAs/Al0.7Ga0.3As multilayer optical filter layer 33, a GaAs light-confining layer 34, GaAs/In0.2Ga0.8As multilayer quantum well active layer 35, GaAs light- confining layer 36, Al0.7Ga0.3As carrier confining layer 37 are laminated, an SiO2 antireflection film 38 is laminated by the electron beam deposition, etc., and a Ti film 39 having a center circular opening of 0.4 mm diameter for completing a surface-emitting type semiconductor element 44 is completed. To suppress higher mode oscillations with large side spatial spreads, a control pin-hole formed through the Ti film is 0.4 mm diameter, and the surface-emitting type semiconductor element 44 is excited by a semiconductor laser element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device, and more particularly to a semiconductor laser device in which a surface-emitting type semiconductor device is excited by a semiconductor laser device to obtain laser oscillation.

[0002]

2. Description of the Related Art Heretofore, there has been a problem that the practical output of a stripe type single transverse mode semiconductor laser device having a narrow stripe width and a high quality beam is limited to 200 to 300 mW. The main causes are as follows. First, in a high-power region, the supply of carriers for generating laser light is limited by the diffusion process of the carriers themselves, so that at a location where the laser beam intensity is high, the carrier concentration is reduced, and so-called spatial holes are generated. The burning phenomenon occurs. As a result, the refractive index of the semiconductor increases, affecting the waveguide mode, deteriorating the beam quality and causing a kink in the current-light output characteristics. Second, in the case of a narrow stripe laser, for example, when the stripe width is 4 μm and the equivalent beam diameter in the direction perpendicular to the junction is 0.5 μm, the output is 300 μm.
At mW, the output density is as high as 15 MW / cm ² , so that the load on the semiconductor laser is large and various deteriorations occur. Therefore, there is a problem that it is not easy to obtain high reliability.

For the former, a waveguide structure is optimized, and for the latter, an end face protective film is optimized and an end face window structure is developed. However, these technologies are approaching their limits, and in order to realize a higher-quality high-quality beam in a semiconductor laser, a new mode control technology and a reduction in light density due to an increase in emission area are essential.

For this reason, spatially coherent and several hundred meters
Various attempts have been made to realize a semiconductor laser device having a high output of W or more. For example, published in 1994
The laser device described in "Diode Laser Arreys" by Botez and DRScifres of Camdridge University Press. However, these structures for realizing a high-quality beam monolithically have a drawback that the structure and the manufacturing process are complicated.

As a means for overcoming the drawbacks of the conventional current injection type semiconductor laser described above, US Pat.
No. 37 and U.S. Pat. No. 5,628,853 propose an optically pumped surface-emitting type semiconductor laser device. However, the devices described therein use the thermal lens effect of the semiconductor, that is, the effect of increasing the refractive index when the temperature increases, so that the temperature basically needs to be increased,
There is a disadvantage that the spatial oscillation mode is sensitive to the temperature distribution and becomes unstable. Further, at high power, the plasma effect peculiar to the semiconductor medium, that is, the effect of decreasing the refractive index due to the increase of carriers, is due to the spatial carrier hole effect (spatial hole burning) for generating high-power laser light. ) Has the disadvantage that the spatial mode becomes unstable.

[0006] Also, Jpn.J.Appl.phys.Let issued in 1997
t., Vol.37.pp.L1020, InGaN / GaN /
AlGaN-Based Laser Diodes Grown on GaN Substrares w
InGaN described in itha Fundamental Transverse Mode
It is desired that a high-output single transverse mode operation can be performed even in a short wavelength semiconductor laser of a system.

Further, IEEE Photonics Tecno published in 1999
400mW Single-frequency 660nm semiconductor laser by B. Pezeshki et al. in logy Letter, Vol.11.p791
In the wavelength range of the AlGaInP-based red semiconductor laser described above, it is desired to have higher output and higher quality than before.

On the other hand, in the conventional semiconductor laser-pumped solid-state laser, it is difficult to obtain a high-speed modulated beam of an oscillation beam by direct modulation of the semiconductor laser, which is an excitation light source, because the fluorescence life of the rare earth element in the laser crystal is very long. Met.

[0009]

It has been very difficult to obtain single transverse mode oscillation in the above-described semiconductor laser device.

Also, it has been very difficult to obtain a high-speed modulated beam of an oscillation beam by direct modulation in a semiconductor laser-pumped solid-state laser.

In view of the above circumstances, it is an object of the present invention to provide a highly reliable semiconductor laser device that oscillates in a fundamental transverse mode from a low output to a high output region.

[0012]

According to the present invention, there is provided a semiconductor laser device comprising: an excitation light source comprising a semiconductor laser element; and an excitation light source which emits laser light having a wavelength longer than that of the excitation light emitted from the excitation light source. A surface-emitting type semiconductor device having an active layer on a substrate and a mirror formed on the substrate side of the active layer or on the side opposite to the substrate; and a surface-emitting type semiconductor device disposed outside the surface-emitting type semiconductor device. In a semiconductor laser device having at least one external mirror forming a resonator, the surface-emitting type semiconductor element has a spatial mode control unit.

It is desirable that the spatial mode control section is a hole-shaped light transmitting section formed on the light emitting end face of the surface-emitting type semiconductor element and transmitting the laser light.

Further, the spatial mode control section may be the mirror partially formed on a plane parallel to a plane from which the laser beam is emitted.

[0015] The spatial mode control section may be the active layer partially formed on a plane parallel to a plane from which the laser beam is emitted.

The size of the spatial mode control unit is desirably 0.1 to 10 times the diameter of the laser beam at the place where the spatial mode control unit is formed.

Further, a wavelength control means may be provided in the external resonator.

Further, a polarization control means may be provided in the external resonator.

Further, the active layer of the semiconductor laser device is formed of In.
consists _v1 Ga _1-v1 N, well active layer of the surface-emitting type semiconductor device is consisted of In _v2 Ga _1-v2 N, in which case, that the composition ratio is 0 <v1 <v2 <1 desirable.

Further, the active layer of the semiconductor laser device has
The active layer of the surface-emitting type semiconductor device may be made of an AlGaInP-based or GaInP-based composition.

The active layer of the semiconductor laser device is formed of In.
consists _w1 Ga _1-w1 As, that the active layer of the surface-emitting type semiconductor device may be comprised of In _w2 Ga _1-w2 As, in which case, the composition ratio is 0 <w1 <w2 <1 Is desirable.

Note that the light transmitting portion has a structure that transmits laser light only through holes and does not transmit laser light through portions other than holes.

Further, the term “InGaN-based” indicates a composition containing at least In element, Ga element and N element. The same applies to AlGaInP-based and GaInP-based.

[0024]

According to the semiconductor laser device of the present invention, in a semiconductor laser device in which a semiconductor laser element is used as an excitation light source and a surface-emitting semiconductor element is excited to perform laser oscillation, a space control unit is provided in the surface-emitting semiconductor element. With this configuration, it is possible to effectively suppress the instability of the spatial mode due to the influence of the thermal lens and the plasma effect. Therefore, in a semiconductor laser device in various wavelength bands, it is possible to obtain high-quality laser light that maintains a stable fundamental transverse mode in a wide output range from low output to high output, particularly in a high output region.

More specifically, by forming a hole-shaped light transmitting portion or a partially active layer on the light emitting surface as a spatial mode control portion, it is possible to increase the resonator loss in a higher-order mode than in the fundamental mode. Therefore, the higher-order transverse mode is controlled, and the fundamental transverse mode oscillation can be obtained.

Further, by partially forming the reflection film, the fundamental mode can be selectively reflected highly, and the resonator loss in the higher-order mode can be increased more than in the fundamental mode. Higher order transverse modes can be controlled.

By setting the size of the spatial mode control unit to be 0.1 to 10 times the diameter of the laser beam at the place where the spatial mode control unit is formed, a good beam shape and good characteristics can be obtained. Obtainable.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings.

A description will be given of a semiconductor laser device according to the first embodiment of the present invention. FIG. 3 is a configuration diagram of the semiconductor laser device, and FIG. 1 is a cross-sectional view of an excitation 810 nm band semiconductor laser device included in the semiconductor laser device.
FIG. 2 is a cross-sectional view of a surface-emitting type semiconductor device which oscillates in a single transverse mode by excitation of the semiconductor laser device.

First, a description will be given of a semiconductor laser device for excitation in the 810 nm band. As shown in FIG. 1, an n-GaAs buffer layer 12 and n-Al _0.63 Ga _{0.37 are formed} on an n-GaAs (001) substrate 11 by metal organic chemical vapor deposition.
As clad layer 13, n or i-InGaP optical waveguide layer
14, InGaAsP single quantum well active layer 15, p or i-InGaP optical waveguide layer 16, p-Al _0.63 Ga _0.37 As
A cladding layer 17 and a p-GaAs cap layer 18 are formed.
After removing the cap layer 18 with an ammonia-based etchant except for a width of 100 μm corresponding to the oscillation stripe, an insulating film 19 is formed, and the cap layer is formed by ordinary lithography.
The region of the stripe on 18 is removed, and a p-side electrode 20 is formed. Thereafter, the substrate is polished to form an n-side electrode 21,
After forming a resonator by cleavage, a high-reflection coat and a low-reflection coat are applied to each end face, and the semiconductor laser device 24 is completed by chipping.

Next, a description will be given of a surface emitting type wavelength conversion element to be excited. FIG. 2 (a) is a sectional view and FIG. 2 (b) is a top view.

As shown in FIG. 2A, a GaAs buffer layer 32 is laminated on a GaAs (001) substrate 31 by a metal organic chemical vapor deposition method, and then a multilayer optical filter layer made of GaAs / Al _0.7 Ga _0.3 As is formed. 33 (Bragg reflector), GaAs
s light confinement layer _{34, GaAs / In 0.2 Ga 0.8} As multiple quantum well active layer 35, GaAs light confinement layer 36, Al _{0. 7}
A Ga _0.3 As carrier confinement layer 37 is laminated. Thereafter, the SiO ₂ anti-reflection film 38 is formed by an electron beam evaporation method or the like.
Are laminated. A Ti film 39 excluding a circular portion having a central portion having a diameter of 0.4 mm is formed thereon by a lift-off method using electron beam evaporation and photoresist patterning. Thereafter, the GaAs substrate 31 is polished, and the GaAs substrate 31 and the GaAs buffer layer 32 in a region wider than the region corresponding to the oscillating portion are selectively etched away to form a hole through which the excitation light is transmitted. Thereafter, an SiO ₂ layer 40 serving as an anti-reflection film is formed for 810 nm which is the excitation light, and finally a chip is formed by cleavage to complete the surface-emitting type semiconductor element 44. As shown in FIG. 2B, the surface-emitting type semiconductor element 44 has a hole-shaped Ti film 39 formed thereon.

Here, the multilayer optical filter layer 33 is designed to have, for example, a high reflectance of 90% or more at 980 nm for laser oscillation and a low reflectance of 5% or less for 810 nm as excitation light. For example, for a wavelength longer than the oscillation wavelength, GaAs / Al becomes １ ／ wavelength in the crystal.
A structure in which about 20 pairs of a _0.7 Ga _0.3 As multilayer structure are stacked is adopted.

Next, the semiconductor laser device will be described with reference to FIG. This semiconductor laser device uses the semiconductor laser element 24 for excitation, and a perforated heat sink in which the GaAs substrate 31 side of the surface emitting semiconductor element 44 is mounted.
52, a concave mirror 54 as an output mirror, and a concave mirror 54
AlGaAs / GaAs of surface-emitting type semiconductor device 44
An external resonator (resonator length L) constituted by the s multilayer optical filter 33 and a wavelength selection element 53 in the external resonator. The AlGaAs / GaAs multilayer optical filter 33 functions as a mirror.

By forming the heat sink 52 as shown in FIG. 3A, heat can be dissipated. The 810 nm excitation light 55 of the excitation semiconductor laser 24 is applied to the surface-emitting type semiconductor element 44.
Are efficiently absorbed by the light confinement layers 34 and 36 and the multiple quantum well active layer 35, and laser oscillation 56 occurs at a wavelength of about 980 nm.

As shown in FIG. 3B, the laser beam 55 of the device 24 of the semiconductor laser for excitation is a surface-emitting type semiconductor device.
The light 44 may be incident at an angle.

Here, due to the design, the beam diameter at the location of the spatial filter of the pinhole made of the Ti film is 1 / e ^2.
The diameter of the control pinhole formed in the Ti film was set to 0.4 mm in diameter in order to suppress the higher-order mode oscillation having a large spatial spread. The smaller the hole diameter, the better the spatial mode controllability. However, if the hole diameter is too small, the amount of blocking of the fundamental mode light increases and the loss increases, so that the beam diameter can be obtained by optimization to obtain desired characteristics. Is preferably in the range of 0.1 to 10 times.

Further, in order to obtain a single longitudinal mode, for example, a Rio filter, an etalon, or a plurality of these may be inserted as the wavelength selection element 53.

The polarization can be controlled by inserting a Brewster plate.

Further, by directly modulating the semiconductor laser element 24 for excitation, a modulated signal modulated at high speed can be obtained. This is a characteristic that cannot be realized by a conventional solid-state laser.

As shown in this embodiment, the excitation light
Use broad area semiconductor laser device as source
High output, for example, 1W to 10W or more
It is. Therefore, the obtained oscillation output is several hundred mW to several
High output of W or more is possible. The aforementioned stripe type single
The beam area at the light emitting end face of the mode laser is generally
2 μm^TwoAbout 0.15mm²
× π = 70650 μm ²And 10⁴More than twice as large beam
Because of the area, high output can be achieved.

Further, since the surface emitting semiconductor device of this embodiment is optically pumped, it differs from a normal current injection semiconductor laser in that heat generation due to an increase in electric resistance in a semiconductor multilayer reflector or the like and reduction in efficiency are caused. There is no problem, such as a conventional surface emitting laser, a complicated composition such as providing a composition gradient layer at the interface between the layers constituting the multilayer optical filter or reducing the resistance by local doping. No structure is required, and the creation process is simpler.

Further, since the semiconductor laser device according to the present embodiment is optically pumped, there is no problem of diffusion of doping material such as Mg, unlike a normal current injection semiconductor laser device, and deterioration with time due to short-circuit is prevented. No, it can extend the life.

Next, a semiconductor laser device according to a second embodiment of the present invention will be described.

FIG. 4 is a cross-sectional view in the stacking direction of a surface-emitting type semiconductor element oscillating at 980 nm constituting the semiconductor laser device according to the second embodiment, and FIG. 5 is a structural view of the semiconductor laser device.

First, the surface-emitting type semiconductor device will be described. As shown in FIG. 4, G was grown by metalorganic chemical vapor deposition.
A GaAs buffer layer 62 is laminated on an aAs (001) substrate 61, and 20 pairs of GaAs (thickness: λ / 4n _GaAs ) /
Al _0.7 Ga _0.3 As (thickness: λ / 4n _{Al0.7Ga0.3As)} Bragg reflector 63, GaAs light confinement layer 64, GaAs /
After growing the In _0.2 Ga _0.8 As multiple quantum well active layer 65, the multiple quantum well active layer is formed into a cylindrical shape with a diameter of about 0.5 mm by a chemical etchant in which sulfuric acid, hydrogen peroxide and water are mixed. Etch 65. This etching may reach part or all of the thickness of the multiple quantum well active layer or the GaAs light confinement layer 64 underneath. Thereafter, a GaAs light confinement layer 66 and an Al _0.7 Ga _0.3 As carrier confinement layer 67 are stacked by a second metal organic chemical vapor deposition method. Then, by electron beam evaporation,
An SiO ₂ (thickness: λ / 4n _{SiO 2} ) antireflection film 68 is laminated. Thereafter, the GaAs substrate 61 is polished, and cut into chips by cleavage to complete the surface-emitting type semiconductor element 74.
Unlike the first embodiment, the GaAs substrate 61 and the GaAs buffer layer 62 are not partially removed.

Next, the semiconductor laser device will be described.
As shown in FIG. 5, the surface emitting semiconductor element 74 is made of GaAs.
The s substrate 61 side is attached to a heat sink. Excitation is performed by the wide 810 nm band semiconductor laser device 24 as in the first embodiment. The light emitted from the surface-emitting type semiconductor device 74 is composed of a 20-pair AlGaAs / GaAs Bragg reflecting mirror 63 and an external mirror, which serve as a mirror.
Resonating with an external resonator (resonator length L) constituted by 84 and laser oscillation 86 in the 980 nm band. A Brewster plate 83 for controlling the polarization is arranged in the external resonator, and controls the polarization.

Since the surface-emitting type semiconductor element 74 has no structure for blocking the excitation light on the opposite side of the GaAs substrate 61, the semiconductor laser device of the present embodiment is configured to perform excitation from the front side opposite to the substrate. . By partially forming the active layer corresponding to the beam diameter, higher-order transverse mode oscillation is suppressed, and stable fundamental transverse mode oscillation can be realized.

Since the entire surface of the surface-emitting type semiconductor element 74 is held by the heat sink, the heat radiation is good and the output can be further increased.

Next, a description will be given of a semiconductor laser device according to a third embodiment of the present invention. FIG. 6 is a cross-sectional view in the stacking direction of a 370 nm band semiconductor laser element for excitation which constitutes the semiconductor laser device. FIG. 7A is a cross-sectional view of a surface-emitting type semiconductor element which is excited by the semiconductor laser element and realizes single transverse mode oscillation, FIG. 7B is a top view, and FIG. FIG.

First, the semiconductor laser device for excitation will be described. Jpn.J.Appl.phys.Lett., Vol. 3 issued in 1997
7.pp.L1020 InGaN / GaN / AlGaN-Based La by Nakamura et al.
ser Diodes Grown on GaN Substrares with a Fundamen
n-GaN by the method described in tal Transverse Mode
A (0001) substrate is formed.

As shown in FIG. 6, a semiconductor laser for excitation is formed on an n-GaN (0001) substrate 91 by a metal organic chemical vapor deposition method on an n-Ga _1-z1 Al _z1 N / GaN superlattice cladding layer 92. (0 <z1 <1), n or i-Ga
_1-z2 Al _z2 N optical waveguide layer 93 (z1>z2> 0), Ga
_{1-z4 Al z4} N _{(Si-doped) / In} x0 Ga
_1-x0 N multiple quantum well active layer 94 (z4> 0, x0 ≧ 0), p
-Ga _{1-z3 Al} z3 N carrier confinement layer (0.35>
z3> z2) 95, p or _{i-Ga 1-z2 Al z2} N optical waveguide layer _{96, p-Ga 1-z1} Al z1 N / GaN superlattice cladding layer 97 (0 <z1 <1) , p-GaN contact Tier 98
To form An insulating film 99 is formed, a stripe region of about 100 μm width of the insulating film 99 is removed by ordinary lithography, and a p-side electrode 100 is formed. Thereafter, the substrate is polished to form an n-side electrode 101, a resonator is formed by cleavage, and a high-reflection coat and a low-reflection coat are applied to each end face to form a chip, thereby completing the semiconductor laser element 104.

Next, the surface emitting semiconductor device will be described. λ is a wavelength oscillated by light excitation, n _AlN ,
_nGaN , _nSiO2 , and _nZrO2 are AlN,
This is the refractive index at the oscillation wavelength of GaN, SiO ₂ , and ZrO ₂ .

As shown in FIG. 7A, metalorganic vapor phase epitaxy
20 pairs on the GaN (0001) substrate 111
GaN (thickness: λ / 4n_GaN) / AlN (thickness: λ /
4n _AlN) Bragg reflector 112, GaN light confinement layer 1
13, In_x2Ga_1-x2N / In_x3Ga_1-x3N
Multiple quantum well active layer 114 (0 <x2 <x3 <0.5), GaN light
Confinement layer 115, Al_x4Ga_1-x4N carrier closed
The embedding layer 116 (x4> 0) is laminated. After that, electron beam steaming
ZrO₂(Thickness: λ / 4n_{Zr 02})Nothing
A reflective coating film 117 is laminated, and the same as in the first embodiment.
Using a similar process, a pinhole
A Ti film 118 is formed. Next, polishing of the substrate 111 is performed.
The excitation light of 370 nm on the back surface of the GaN substrate 111
ZrO of thickness to be anti-reflection film₂Form film 119 and cleave
To complete the surface-emitting semiconductor device 124
You. This surface-emitting type semiconductor element 124 is as shown in FIG.
Thus, the hole-shaped Ti film is formed.

By arranging the semiconductor laser element 104 for excitation and the surface-emitting type semiconductor element 124 formed as described above as shown in FIG. 8, oscillation at a wavelength of 400 to 550 nm is achieved.
It is possible to configure a surface-emitting type semiconductor laser device that performs 136 operations. The semiconductor laser device according to the present embodiment
As shown in the other embodiments, the heat sink 132,
The lens 131, the wavelength selection element 133, the external mirror 134, and the GaN /
An external resonator (resonator length L) formed by the AlN Bragg reflector 112 is provided.

The GaN substrate 111 is transparent to the excitation light, and the sapphire substrate, which is often used, is also transparent, so that the substrate-side excitation laser light can be incident. Further, since these substrates have a large coefficient of thermal conductivity, heat can be easily dissipated by forming a heat sink as shown in FIG. In addition, light emitted from the surface-emitting type semiconductor element undergoes very little beam deformation due to the thermal lens.

Here, Ga is used as a surface-emitting type semiconductor device.
A surface-emitting type semiconductor device having an InGaAs quantum well active layer oscillating at a wavelength of about 900 to 1200 nm formed on an As substrate, and a wavelength of 1300 formed on an InP substrate.
InGaAsP or In oscillating at about -1700 nm
It is also possible to use a surface-emitting type semiconductor element using GaAlAs as an active layer. Since these substrate materials are transparent to the oscillation wavelength, select a pumping semiconductor laser that has a wavelength that is transparent to the substrate material, and use the quantum well and the surrounding barrier layer and optical confinement layer. By employing a composition and a layer structure that can effectively absorb the excitation light, it is possible to employ a configuration in which excitation is performed from the substrate side.

Next, the half according to the fourth embodiment of the present invention will be described.
Description of a semiconductor laser device and its semiconductor laser device
FIG. 9A is a cross-sectional view of a surface-emitting type semiconductor device constituting
FIG. 9B shows a top view. λ oscillates by light excitation
, And n_AlN, N _GaN, N_SiO2, N
_ZrO2Are AlN, GaN, SiO₂, ZrO
₂Is the refractive index at the oscillation wavelength.

First, the semiconductor laser device will be described. As shown in FIG. 9A, on a GaN substrate 141, Al
_{z4Ga1 -z4N} carrier confinement layer 142 (0 <z4 <
1), GaN optical confinement layer 143, _{Inx2Ga1 -x2N}
/ In _x3 Ga _1-x3 N multiple quantum well active layer 144 (0 <
x2 <x3 <0.5), GaN optical confinement layer 145, two pairs of Al
N (λ / 4n _AlN ) / GaN (λ / 4n _GaN ) semiconductor multilayer film 146, 12 pairs of SiO ₂ (λ / 4
_{n SiO2) / ZrO 2 (λ} / 4n ZrO2) laminating a dielectric multilayer film 147. Semiconductor multilayer film 146 and dielectric multilayer film 14
7 forms a Bragg reflector. A Bragg reflector is formed only in a circular region by dry etching, the substrate 141 is polished, an antireflection film 148 for an oscillation wavelength is formed, and a chip is formed by cleavage to complete the surface-emitting type semiconductor element 154. As shown in FIG. 9B, a circular Bragg reflector is formed.

The semiconductor laser device 104 and the surface-emitting type semiconductor device 154 are used as an excitation light source to constitute a semiconductor laser device as shown in FIG. The semiconductor laser device according to the present embodiment includes a heat sink 162 on which the Bragg reflector side of the surface-emitting type semiconductor element is attached, and a lens.
161, a wavelength selection element 163, an external mirror 164, and the external mirror 164 and the Bragg reflector 14 serving as a mirror
An external resonator (resonator length L) constituted by 6, 147 is provided, and a laser oscillation 166 in the 400 to 550 nm band can be obtained.

In the present embodiment, the spatial mode is controlled by the action of selectively reflecting the fundamental mode highly by the Bragg reflectors 146 and 147 formed partially.

Next, a semiconductor laser device according to a fifth embodiment of the present invention will be described. FIG. 11 is a cross-sectional view of a red surface emitting semiconductor device having an oscillation wavelength band of 650 nm constituting the semiconductor laser device. Fig. 12 shows a semiconductor laser device.
Shown in

As shown in FIG. 11, a GaAs substrate (00
1) A GaAs buffer layer 172, In _{0.5
(Ga 1-x5 Al x5)} 0.5 P carrier confining layer
_{173, In 0.5 (Ga 1-} x2 Al x2) 0.5 P optical confinement layer _{174, In 0.5 (Ga 1-} x3 Al x3)
_0.5 P / In _0.5 (Ga _1-x4 Al _x4 ) _0.5
P multiple quantum well active layer 175, In _0.5 (Ga _1-x2
Al _x2 ) _0.5 P light confinement layer 176, In _0.5 (G
a _1−x5 Al _x5 ) _0.5 P carrier confinement layer 177
Are laminated. The above composition desirably satisfies 0 ≦ x3 <x4 ≦ x2 <x5 ≦ 1. Then, by electron beam evaporation, S
The iO ₂ / TiO ₂ multilayer optical filter 178 is laminated. The substrate 171 is polished, and the GaAs substrate 171 and the GaAs buffer layer 172 in a wide area including the light emitting area are removed with a sulfuric acid-based etchant. Next, an antireflection film 179 for excitation light
To form Finally, a Ti film 180 having a pinhole-shaped hole for controlling the spatial mode is formed, and the surface-emitting type semiconductor element 184 is formed.
To complete.

Next, the semiconductor laser device will be described.
As shown in FIG. 12, the surface emitting semiconductor element 184 has the multilayer optical filter 178 side attached to a heat sink 192. The semiconductor laser device according to the present embodiment has an InGaN active layer as excitation light, for example, 400 nm.
A wide semiconductor laser element 190 that oscillates at a time can be used. The light emitted from this excitation light source is condensed inside the surface-emitting type semiconductor element 184 by the lens 191 and has a concave surface of the external mirror 194 and an external resonator (multilayer optical filter 178 serving as a mirror). It resonates with the resonator length L) and obtains a laser oscillation 196 in the 650 nm band from an external mirror. The polarization is controlled by the polarization control element 193 in the external resonator.

The multilayer optical filter 178 has a
It has high reflection of 0% or more and low reflection of 5% or less, preferably 1% or less for excitation light.

In this embodiment, the GaAs substrate 18
1 is an absorption medium for oscillating light, so that the GaAs substrate is thinned with high precision by etching or the like,
Pinhole-shaped holes provided in the substrate or the GaAs buffer layer can be used for mode control.

In all of the above embodiments, a broad area semiconductor laser is used as an excitation light source. However, the excitation semiconductor laser element is not limited to a broad area semiconductor laser element, but may be an array semiconductor laser element or a tapered structure. MOPA (Master Oscil)
lator Power Amplifire) and even α-DFB (angle
d grating-distributed freedback) A laser structure or the like may be used.

Although a single-layer dielectric film is used as an anti-reflection film for oscillation light and excitation light, a low reflectance can be obtained as a multilayer structure. In addition, when the absorption coefficient of the surface emitting semiconductor element for the excitation light is small, in the case of the backside excitation from the side opposite to the side from which the oscillation light is extracted, anti-reflection for the oscillation light and finite for the excitation light It is possible to form a film having the following reflectance, and to use the once reflected excitation light effectively.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a semiconductor laser element as an excitation light source of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a surface-emitting type semiconductor element constituting the semiconductor laser device according to the first embodiment of the present invention;

FIG. 3 is a view showing a semiconductor laser device according to the first embodiment of the present invention;

FIG. 4 is a cross-sectional view showing a surface-emitting type semiconductor element constituting a semiconductor laser device according to a second embodiment of the present invention;

FIG. 5 shows a semiconductor laser device according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a semiconductor laser element that is an excitation light source of a semiconductor laser device according to a third embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating a surface-emitting type semiconductor device constituting a semiconductor laser device according to a third embodiment of the present invention;

FIG. 8 shows a semiconductor laser device according to a third embodiment of the present invention.

FIG. 9 is a cross-sectional view showing a surface-emitting type semiconductor element constituting a semiconductor laser device according to a fourth embodiment of the present invention;

FIG. 10 is a diagram showing a semiconductor laser device according to a fourth embodiment of the present invention.

FIG. 11 is a cross-sectional view showing a surface-emitting type semiconductor device constituting a semiconductor laser device according to a fifth embodiment of the present invention;

FIG. 12 shows a semiconductor laser device according to a fifth embodiment of the present invention.

[Explanation of symbols]

33 AlGaAs / GaAs multilayer filter layer 35 GaAs / InGaAs multiple quantum well active layer 39,118 Ti film 52,82,132,162,192 Heat sink 54,84,134,164,194 External mirror 65 GaAs / InGaAs multiple quantum well active layer 63 AlGaAs / GaAs Bragg reflector 112 AlN / GaN multilayer filter Layer 114,144 InGaN / InGaN multiple quantum well active layer 146 2 pair AlN / GaN reflective film 147 12 pair SiO ₂ / ZrO ₂ reflective film 175 InGaP / In (GaAl) P multiple quantum well active layer 178 SiO ₂ / TiO ₂ multilayer optical filter

Claims (10)

[Claims] An excitation light source comprising a semiconductor laser element, and at least an active layer and an active layer on a substrate, which are excited by the excitation light source and emit laser light having a wavelength longer than the wavelength of the excitation light emitted from the excitation light source. A surface-emitting type semiconductor device having a mirror formed on the substrate side or on the side opposite to the substrate; and at least one external mirror arranged outside the surface-emitting type semiconductor device and forming an external resonator with the mirror The semiconductor laser device according to claim 1, wherein the surface emitting semiconductor element includes a spatial mode control unit. 2. The light emitting unit according to claim 1, wherein the spatial mode control unit is a hole-shaped light transmitting unit formed on a light emitting end face of the surface emitting semiconductor element and transmitting the laser light. Semiconductor laser device. 3. The semiconductor laser device according to claim 1, wherein the spatial mode control unit is the mirror partially formed on a plane parallel to a plane from which the laser light is emitted. 4. The semiconductor laser device according to claim 1, wherein the spatial mode control unit is the active layer partially formed on a plane parallel to a plane from which the laser light is emitted. 5. The size of the spatial mode control unit is 0.1 to 10 times the diameter of the laser beam at the place where the spatial mode control unit is formed. 5. The semiconductor laser device according to 2, 3, or 4. 6. The semiconductor laser device according to claim 1, wherein a wavelength control means is provided in said external resonator. 7. The semiconductor laser device according to claim 1, wherein a polarization controller is provided in the external resonator. 8. The semiconductor laser device according to claim 1, wherein the active layer is In.
consists _v1 Ga _1-v1 N, the active layer of the surface-emitting type semiconductor device is made of _{In v2 Ga 1-v2} N, composition ratio
8. The semiconductor laser device according to claim 1, wherein 0 <v1 <v2 <1. 9. The semiconductor laser device according to claim 1, wherein the active layer is In.
The semiconductor laser device according to claim 1, wherein the active layer of the surface-emitting type semiconductor element is made of an AlGaInP-based or GaInP-based composition. 9. 10. The semiconductor laser device according to claim 1, wherein
n _w1 Ga _1-w1 As, and the active layer of the surface emitting semiconductor device is made of In _w2 Ga _1-w2 As,
The composition ratio is 0 <w1 <w2 <1.
8. The semiconductor laser device according to any one of claims 1 to 7.