JPS62285483A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain a high output by one outgoing beams while acquiring a laser having high reliability by forming a high reflection film to one part of a laser outgoing end-surface. CONSTITUTION:Normal double hetero-structure is grown on a GaAs substrate, to which five groove stripes are shaped, through a liquid growth method. High reflection films 9 are executed to outgoing end surfaces in second and fourth light-emitting striped regions from the left, and laser lights are not emitted from the regions. Consequently, laser lights, 360 deg. phase of which is conformed, are emitted from first, third and fifth stripes from the left. Accordingly, laser lights are intensified mutually in the direction vertical from the outgoing end surfaces, thus forming outgoing beams to one single peak.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention has one output beam and has an optical output of 100 mW.
The present invention relates to the above high-power semiconductor laser device.

[Conventional technology]

One candidate method for realizing a semiconductor laser with an optical output of 100 mW or more is to have a plurality of light emitting stripes and to cause optical coupling between each stripe.

There is a so-called phased array type semiconductor laser.

A typical known example of this phased array type semiconductor laser is the Proceedings of the 32nd Applied Physics Conference, p. 149.
It was disclosed by Tanetani et al.

[Problem that the invention seeks to solve]

In the conventional technology, since oscillation occurs in a high-order mode called a super mode, there are two emitted beams, which causes problems in application.

The reason why a high-order supermode is selected in this conventional structure will be explained below using FIG. 2. The relationship between refractive index and gain (loss) for the structure of Tanaya et al. is schematically shown in FIGS. 2(a) and 2(b). In this way, a gain exists in a region with a high refractive index, and a large loss occurs in a region with a low refractive index. The electric field distribution of the fundamental supermode under these conditions is shown in FIG. 2(,+), and the electric field distribution of the higher-order supermode is shown in FIG. 2(d).

In the region of large loss shown in FIG. 2(b), the electric field distribution of the fundamental supermode does not reach zero, whereas the electric field distribution of the higher-order supermode crosses the zero level.

That is, the loss suffered by the higher-order supermode is smaller than the loss suffered by the basic supermode, and therefore the higher-order supermode has a lower threshold profit? :) decreases. As a result, in the above structure, a higher-order super mode oscillates, resulting in two output beams.

An object of the present invention is to provide a semiconductor laser with a single output beam 11, high output, and high reliability.

[Means for solving problems]

The present inventor has discovered that in a phased array semiconductor laser,
As a method of reducing the number of output beams 11 to one, the highest order super mode is selected inside the laser, the phase of the optical electric field is changed by 180 degrees for each light emitting stripe, and the highest order super mode is output from the output end face. When a high reflection film is applied to every other light emitting stripe, and the output beam 11 is made to emit from every other stripe, 360
゜We devised a method to generate laser light with uniform phase.

As a result, the output beam becomes one single peak beam 11 in the vertical direction from the output end mi. In addition, unless special measures are taken for the stripe structure, the highest-order supermode oscillates stably, as in the structure of Tanaya et al., so even during high-power operation, the output beat t1 is single-peaked as described above. The above purpose was achieved.

　Supplies　

Detailed explanation of the present invention using FIG. 1] I4 (a) is a laser structure, (b) is a refractive index distribution, (
b) shows the electric field distribution of the highest order supermode. In this laser structure, GtrAs with five groove stripes is used.
Grow a conventional double heterostructure on a substrate by liquid phase epitaxy. In this structure, like the structure of Tanetani et al. mentioned above,
In the stripe gap, the laser beam is absorbed by the GaAs=}X plate (so-called CSP effect), so light loss occurs in the stripe gap, and the refractive index of the light emitting stripe increases (FIG. 1(b)). As a result, as in the structure of Taniya et al., the threshold gain of the highest-order supermode (FIG. 6(C)) decreases, so that the highest-order supermode oscillates stably. However, as shown in FIG. 1(a), if a high reflection film 9 is applied to the output end face of the light emitting stripe area No. 2 11 and No. 4 L1 from the left to prevent the laser beam from being emitted from that area, the first The optical electric field in the shaded area in Figure (c) does not come out to the outside. Therefore, laser beams having a uniform 360° phase are emitted from the 1st, 3rd, and 5th stripes from the left. As a result, the laser beams strengthen each other in the direction perpendicular to the output end face, so the output beam becomes one single peak. As this gold reflective film, it is effective to use a multilayer film in which M electric films having different refractive indexes are stacked alternately, or a combination of a dielectric film and a metal film with a high reflectance. In the above description, the case where there are five stripes is shown, but it goes without saying that the present invention is effective regardless of the number of stripes.

〔Example〕

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

Example 1 Figure 1 shows a bird's-eye diagram (a) of a laser device when the present invention is applied to a GsAQAs semiconductor laser, its refractive index distribution (b), and electric field distribution of the highest order supermode (c). be.

Five grooves 10 each having a width of 3 .mu.m and a depth of 1 .mu.m are formed on an n-G5As substrate 1 by a photoetching process.

At this time, the interval between the stripe centers was set to 5 μm.

After this, by liquid phase growth method, n-Gao, sA D
o, sAs cladding layer 2. Undoped GaQ, an^Q
0.14AS activity! Ij3゜p -Gao, 6A Q
A 0.3AS cladding layer 4 and an n-GaAs layer 5 are sequentially formed. After this, p -Gao, 6A Q o, sA
A diffusion region 6 is provided that reaches the s-cladding layer 4.

After forming the p-electrodes 7 and 8 by the lift-off method and subsequently forming the n-electrode a, a laser element with a cavity length of about 300 μm was obtained by the cleavage method.

After this, a 135 nm thick 5iOz film (^i refractive index), 4
5) and amorphous Si (refractive index 3.3) having a film thickness of 59 nm were alternately formed into a multilayer film 9 consisting of two layers each.

This multilayer film 9 provides a reflectance of 95% at that portion. At this time, n -Gao on the groove gap, sA Q o
, 6^S When the thickness of the cladding layer is O,L-0,5 μm, a refractive index distribution as shown in FIG. 1(b) is formed.

The prototype device has a threshold current of 100 to 1.
Continuous oscillation was performed at 50 mA and a wavelength of 780 nm, and the oscillation spectrum showed a single longitudinal mode. Its far-field pattern (emission distribution in the direction parallel to the cemented surface) shows a single peak, and a single output beam with a half-width of 2° is obtained at an output angle of 0°, and the optical output is stable up to 400 mW. was gotten.

In other words, according to this example, it was found that inside the laser, when the highest order supermode oscillates and is emitted, the optical electric field of the opposite phase is blocked by the highly reflective film.

Example 2 FIG. 3 shows another embodiment according to the present invention.

n GaAs group, double crystal 1°7 n-(iao,
5A 12 a, 6AS cladding layer 2, undoped Gao, aoA Q, 0.14A8 active layer 3,
p-Gao, sAQo, 3^S cladding layer 4, n-
A GaAs current constriction layer 11 is sequentially formed by the M OC and V rl methods.

The n-GaAs 1 is completely removed by a photo-etching process, and five groove stripes each having a width of 4 μm are formed to expose the surface of the p-Gao, sAD, o, aAs Clara 4.

At this time, the interval between the centers of each stripe was set to 6 μrn.

Next, using the MOCVI') method, P Gao, sA Q
A third cladding layer 12 and a p-GaAs cap layer 13 are formed on +1 and +6. After this, p electrode 7. After forming the n-electrode 8, a laser device with a cavity length of about 300 μm was obtained by the cleavage method.

Thereafter, first, a 5102 film with a thickness of 270 nm and a two-layer film 14 of Au with a thickness of 300 nm were formed on the emission end faces of the second and fourth light emitting stripes from the left. This 2
The reflectance of the layer film is approximately I,00%. At this time, p −
Gao, 5A Q o, aAsAs Clara 4 thickness is
O01 ~ 0.5 μm, and under these conditions we were able to realize a refractive index guided type, low aberration, high output phased array laser.6 The prototype device has a threshold current of 100~0. ], continuous oscillation was performed at room temperature at 20 mA, and the oscillation spectrum showed a longitudinal single mode. The far-field image was unimodal, and its half-width was 1.5° x 25°. Moreover, stable characteristics were obtained up to a light output of 300 mW. Further, at 50''C, optical output 300 mW constant light: J-% power operation II;'i+ (7) R life showed no significant deterioration even after 2000 hours, and reliability was high.

In addition, in the present invention, the stripe structure in each example has a number of 2 to 20 stripes, a stripe width of 1 to 10 μm, and a spacing between stripe centers of 2 to 12 μm. It worked. It goes without saying that the basic stripe structure of the present invention may be of any shape other than those described above, such as a BH structure, a rib waveguide trough structure, etc.

Note that the present invention is not limited to the wavelength of around 0.78 μm shown in the examples, but also GaA Q As with a wavelength of 0.68 to 0.89 μm.
Similar results were obtained over the entire range of continuous oscillation at room temperature using a semiconductor laser device based on this method. The semiconductor laser device according to the present invention uses a laser material other than GaA Q AS type, such as T.
The present invention can be similarly applied to nGaP-based P-based and TnGaP-based materials. Furthermore, the structure of the laser is not limited to one based on the three-layer waveguide shown in each of the above embodiments, but may also include a 50C structure in which a light guide layer is provided adjacent to one side of the active layer, or a structure in which a light guide layer is provided adjacent to both sides of the active layer. S to provide a light guide layer.
G old N-S CT-I in which the CH structure and the refractive index and forbidden band of these optical guide layers are distributed in the film thickness direction.
The same can be applied to structures, etc. Furthermore, it is also effective for those in which the active layer has a quantum well structure, and in each of the above embodiments, the conductivity types are all reversed (a structure in which p is replaced with n and n is replaced with p). A similar effect was obtained.

〔Effect of the invention〕

According to the present invention, in a phased array semiconductor laser in which the highest-order supermode oscillates inside the laser, by applying a high reflection film to a part of the emission end face, the output beam becomes one. Unimodal high output (>1
This has the effect of easily realizing a semiconductor laser (00 mW).

[Brief explanation of the drawing]

FIGS. 1 and 3 are diagrams showing embodiments of the present invention. FIG. 2 is a diagram showing a supermode of a conventional phased array laser. 1-n-GaAs substrate, 2-n-Gao, 5^QO0
5^S cladding layer; 3. undoped Gao, saA
Q O, L4AS active layer, 4-p-Gao, 5A
O, o, bAs cladding layer, 5-p-GaAs layer, 6
...Zn diffusion region, 7...n electrode, 8...n electrode, 9...high reflection film, 10...light emitting stripe groove. 11...n GaAs current confinement layer, 12...p-
Gao, 6^Qn, sAsM, 13-= p-(';
aAs cap layer, 14...high reflection film.

Claims (1)

[Scope of Claims] 1. A semiconductor laser device having at least two or more laser emission stripes optically coupled to each other, characterized in that a high reflection film is provided on a part of the emission end facet. . 2. A semiconductor laser device having at least two laser emitting stripes optically coupled to each other, characterized in that a high reflection film is provided on the emission end face of the emitting stripe for every other emitting stripe. Semiconductor laser equipment. 3. The semiconductor laser device according to claim 2, characterized in that a high reflection film is provided on the emission end face of every other light emitting stripe and the stripe gap region adjacent to both sides thereof. . 4. The semiconductor laser device according to claim 2, characterized in that a high reflection film is provided on the emitting end face of every other light emitting stripe and part of the stripe gap region adjacent to both sides thereof. Semiconductor laser equipment. 5. A semiconductor laser device according to any one of claims 1 to 4, characterized in that a semiconductor layer that absorbs light generated from the active layer is provided in the stripe gap region. 6. A semiconductor laser device according to claims 1 to 5, wherein the high reflection film has a reflectance of 60% or more, particularly 85% or more. 7. In the semiconductor laser device according to any one of claims 1 to 6, the high reflection film is a first film having a refractive index of n_1 and a film thickness of λ/4n_1 (λ: laser wavelength).
or a combination of a dielectric film and a metal film. A semiconductor laser device characterized in that: