JPH0376188A - Semiconductor laser array - Google Patents

Abstract

PURPOSE:To reduce the effect of heat generation from a laser and to enable convergence of light by using a lens, etc., by making the spacing of adjacent waveguides at a central section wider than that of adjacent waveguides in the vicinity of at least one end face. CONSTITUTION:Three waveguides 1 in total are juxtaposed between both end faces 11, 12 in response to each semiconductor laser in a laser chip 10. The juxtaposed formation patterns of each waveguide 1 differ in three regions in the longitudinal direction of the laser chip 10, spacing between adjacent waveguides 1, 1 is narrowed in a region A in the vicinity of the end face 11, the waveguides 1 are spread radially in a central region B, and spacing betwe77 en adjacent waveguides 1, 1 is widened in a region C in the vicinity of the end face 12. The bent section of the waveguides 1 are formed in a circular shape in order to reduce radiation loss, and distances from the waveguides 1 at both ends to side faces in the region C can be lengthened as much as possible in order to improve heat dissipation from the waveguides 1, 1. When the spacing D1 of adjacent waveguides in the vicinity of the end face 11 is brought to 8mum or less, a laser beam can be converged to a point by use of a lens, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor laser array used for optical information processing, laser processing, or the like.

[Conventional technology]

Generally, in a semiconductor laser, when the drive current is increased to increase the optical output, the pn junction generates heat, and the optical output is thermally saturated due to the increase in the threshold current density and the decrease in the external differential quantum efficiency. The maximum optical output of each semiconductor laser is determined by this thermal saturation or optical end face destruction accompanying an increase in optical output.

With the expansion of the application range of laser light emitted from semiconductor lasers, the demand for high-power laser light is increasing.
As a means of obtaining high-output laser light, there is a semiconductor laser array in which a plurality of semiconductor lasers each having a waveguide are arranged in parallel (K, Ha□ada atat, 5olid-
5tate Electronics Vol, 30+
No. 1 pp33-37.1987). There are two types of such semiconductor laser arrays: a phase-locked type in which the phases of the laser beams from each semiconductor laser are aligned, and a non-phase-locked type in which the phases of the laser beams from each semiconductor laser are not aligned. There are different types.

[Problem to be solved by the invention]

In the phase-locked semiconductor laser array described above, in order to phase-lock the laser beams generated in each waveguide, the distance between adjacent waveguides must be set to about 5 μm or less. However, in such a configuration, since the semiconductor lasers are closely arranged in parallel, they are easily affected by the heat generated by each semiconductor laser, and the temperature rise at the pn junction is large, resulting in a decrease in optical output. Saturation tends to occur, making it impossible to obtain high-power laser light.

In order to prevent such heat generation from each other between the semiconductor lasers, each semiconductor laser in the array must be separated by several tens of micrometers.
A configuration in which the semiconductor lasers are spaced apart from each other (a non-phase synchronized semiconductor laser array in which phase synchronization cannot be applied between each semiconductor laser)
And it is sufficient. However, this configuration has the disadvantage that since the adjacent semiconductor lasers are too far apart, the beam light emitted from each semiconductor laser cannot be focused on one point using a lens or the like.

The present invention has been made in view of the above circumstances, and by shortening the interval between the waveguides near the end face and increasing it at the center, it is possible to reduce the influence of heat generated from each semiconductor laser, and moreover, it is possible to reduce the influence of heat generation from each semiconductor laser, and moreover, it is possible to reduce the influence of heat generation from each semiconductor laser. An object of the present invention is to provide a semiconductor laser array that can be used to condense beam light from each semiconductor laser to one point.

[Means to solve the problem]

In the semiconductor laser array according to the present invention, in a semiconductor laser array in which a plurality of waveguides are arranged in parallel, the distance between the adjacent waveguides in the center is smaller than the distance between the adjacent waveguides in the vicinity of at least one end face. It is characterized by wide spacing between the wave channels.

[Effect]

In the semiconductor laser array of the present invention, the distance between adjacent waveguides is narrow near the end face, and each laser beam emitted from the end face after passing through each waveguide is focused at one point by a lens or the like. Further, in the central part, the distance between adjacent waveguides is wide, so that the heat generated from each semiconductor laser has less influence on the adjacent semiconductor lasers, so that the optical output is less likely to be thermally saturated, and the optical output can be increased.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof.

FIG. 1 is a plan view of a semiconductor laser array according to the present invention, and FIG. 2 is a partial sectional view taken along line nn in FIG. 1.

In FIG. 1, 10 indicates a laser chip, and this laser chip 10 has a rectangular shape with a length (resonance length) between both end faces 11 and 12 of 750 μm and a width of 600 μm in plan view, and corresponds to each semiconductor laser. A total of three waveguides l are arranged in parallel between both end faces IL12.

Note that the end faces are coated so that the reflectance of the end face 11 on the left side in the figure is 90%, and the reflectance of the end face 12 on the right side is 8%.

Here, the element structure of this example will be explained based on FIG. In FIG. 2, 2 is an n-GaAs substrate (Si-doped, n = 2 XIO" cm-3), and on the substrate 2 is an n-Gao, 58A10.4Js craft layer (Se-doped).

n = 5 XIO"am-', film thickness 2.0μm)
3, Gao, 5J1o,.

As active N (non-doped, WX film thickness, 07/' m)
4, p-Gao, 5sAlo, azAs cladding layer (Zn doped, p = 2XIQ"cm-" film thickness 1
,5. crm) 5, p-GaAs camp F! (
Zn doped.

= l XIO19am-', film thickness 0.5 μm)6
are layered in this order. The p-cladding layer 5 and the cap layer 6 are removed in an inverted mesa shape at a predetermined pitch, and an n-GaAs block layer (Se-doped, n=5×1QIIC11-3, film thickness 1.0μ) is formed in the removed portion.
m) 7 is formed. In this embodiment, each waveguide 1 forms a zigzag stripe. In addition, in order to obtain a stable fundamental transverse mode in each waveguide 1, the distance (1) from the lower end of the block layer 7 to the upper surface of the active layer 4 is t =
0.1 to 0.2 μm, and the width (W) of the waveguide is W=3
~4 μm.

The parallel formation patterns of each waveguide 1 are different in three regions in the longitudinal direction of the laser chip 10. End face 1
In a region A in one vicinity, adjacent waveguides l.

In the central region B, the waveguides 1 are expanding radially, and in the region C near the end face 12, the distance between adjacent waveguides 1.1 is wide. The specific shape of the ridge-like stripe of the waveguide l is as follows.

Length LI of region A = 50 μm.

Length Lz of region B = 550 μm.

Length L3 of area C = 150. crm.

Distance between waveguides in region A = 3 μm.

Distance between waveguides D2 in region C = 100 μm Here, the bent portion of waveguide 1 (regions A, B and B).

It is preferable that the boundary (C) has a circular arc shape in order to reduce radiation loss, and the radius of curvature of this circular arc is at least 1 to 2 mm or more. In addition, the waveguides 1 located at both ends. 1
In order to improve heat dissipation from the region C, it is desirable that the distance from the waveguide 1 at both ends to the side surface (in the first diagram) be as long as possible (approximately 150 μm). In addition,
The distance DI between adjacent waveguides near the end face 11 is 8μ.
If it is less than m, the laser light from each waveguide can be focused on one point using a lens or the like.

Next, a comparison of current-light output characteristics between an example of the present invention and a conventional example will be explained. FIG. 3 is a graph showing the characteristics on both sides, in which (a) represents the characteristics in the case of the above-mentioned example of the present invention shown in FIGS. 1 and 2, and (b) in the graph shows the characteristics as shown in FIG. This shows the characteristics of a conventional example. Figure 4 is a plan view of the conventional example used here, and the distance between the end faces is 750 μm.
The three waveguides 21 are formed in parallel between both end faces of the laser chip 20 of 1.m, and the spacing between adjacent waveguides 21 and 21 is the same (6 μm) in all regions.

As understood from FIG. 3, in the conventional example (b), the optical output is saturated at 190 mW. On the other hand, in Example (a) of the present invention, there is a shift in oscillation between the central laser and the lasers at both ends, so the curve showing the current-light output characteristics is bent, but the optical output does not saturate until 240 mW. . As described above, in the semiconductor laser array of the present invention, the optical output is less likely to be thermally saturated than in the prior art.

In the semiconductor laser array of the present invention, since the interval between adjacent waveguides in the central portion is wide as described above, it is possible to reduce the influence of heat emitted from each semiconductor laser and increase optical output.

Furthermore, since the distance between adjacent waveguides is narrowed near the end face, the laser light from each semiconductor laser can be focused on one point using a lens or the like.

〔Effect of the invention〕

As detailed above, in the semiconductor laser array of the present invention, the interval between adjacent waveguides is narrowed near the end facets, and the waveguides are expanded radially in the center. The emitted laser light can be focused on one point, and the optical output is less likely to be thermally saturated, making it possible to achieve high output laser light.Therefore, it is useful in optical information processing and laser beam processing. The present invention has excellent effects such as being able to further expand the range of application as a light source.

[Brief explanation of drawings]

FIG. 1 is a plan view of a semiconductor laser array according to the present invention, FIG. 2 is a partial cross-sectional view taken along line nn in FIG. 1, FIG. 3 is a graph showing current-light output characteristics, and FIG. 4 is a conventional FIG. 2 is a plan view of a semiconductor laser array of FIG. 1... Waveguide 2... Substrate 3... N-clad N4... Active layer 5... P-clad layer 6...
Camping layer 7...Block 1 10...Laser chip 11.12...End face

Claims (1)

[Claims] 1. In a semiconductor laser array in which a plurality of waveguides are formed in parallel, the distance between the adjacent waveguides in the central portion is greater than the distance between the adjacent waveguides in the vicinity of at least one end face. A semiconductor laser array characterized by wide spacing.