JPS63142886A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To prevent the breakdown of end surfaces, and to enable stable high output operation by forming two parallel ridges onto a substrate so that the height in the vicinity of the end surfaces is heightened and shaping each layer including an active layer onto the substrate. CONSTITUTION:A mesa in height of 6mum is formed onto a P-type GaAs substrate (100) face in the <011> direction through etching. An N-type blocking layer 2 is grown onto the substrate, and two parallel ridges 7 are shaped to a growth surface through etching. Each layer containing an active layer is formed onto a wafer, to which the ridges are shaped, through a liquid phase epitaxial method. Consequently, when the growth is conducted onto the ridges in a tall height only in the vicinity of end surfaces, the active layer thinner in the vicinity of the end surfaces than the inside of a laser can be formed. As a result, since beams are spread largely to clad layers (3 and 5) from the active layer 4 in the vicinity of the end surfaces, the spot size of the laser is extended, thus lowering optical output density. Accordingly, a maximum optical output where the end surfaces are broken is elevated, thereby allowing an operation with a higher output.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a semiconductor laser device.

BACKGROUND OF THE INVENTION Semiconductor laser devices have come into widespread use for reading signals on optical disks, as light sources for laser beam printers, and for optical communications. In most of these optical information devices, the required laser output was 20 mW or less. However, in recent years, there has been an increasing demand for high-power semiconductor lasers for applications such as writing on optical discs.

Problems to be Solved by the Invention However, when conventional semiconductor lasers are driven at high power, the crystals at the end face absorb the laser beam and melt, resulting in so-called end face destruction, making stable high power operation difficult. It had been.

In view of the above-mentioned problems, the present invention provides a semiconductor laser device that can prevent end face breakage and perform stable high output operation.

Means for Solving the Problems In order to solve the above-mentioned problems, the semiconductor laser device of the present invention has two parallel ridges written on the substrate so that the height near the end face is high, and Each layer including the active layer is described and configured thereon.

Effect: This configuration reduces the thickness of the active layer in the vicinity of the end facets, thus increasing the laser spot size at the end facets and lowering the optical output density, thereby enabling high power operation.

EXAMPLE A first example of the present invention will be described below with reference to the drawings.

A mesa having a height of 6 μm as shown in FIG. 4 is formed in the (011) direction on the pWGaAs substrate 1 (1oo) plane by etching. An n-type blocking layer 2 is grown on this substrate, and then two parallel ridges 7 as shown in FIG. 1 are formed on the growth surface by etching. The width of each ridge is 20 μm.

The width of the groove between the ridges is 6 μm. And from the end face 20
The substrate is deeply etched to have a ridge height of 6 μm near the end face within μm, and the height of the ridge is 1.6 μm at the center of the laser other than near the end face. Each layer including the active layer is formed on the wafer with the ridge formed thereon by a liquid phase epitaxial method. Ohmic electrodes are formed on the front and back surfaces of the grown wafer, and a laser chip is obtained by forming a cavity with a cavity length of 260 μm.

FIG. 6 shows a cross-sectional view near the end face of the laser manufactured through the above process, and FIG. 6 shows a cross-sectional view inside the laser.

Since the semiconductor laser device of this embodiment has the above configuration, it has the following effects.

When a film is grown by liquid phase epitaxial method on a substrate having a ridge, the film thickness on the ridge becomes thinner due to the anisotropy of crystal growth. This effect is greater as the height of the ridge is higher. Therefore, if growth is performed on the high ridge only near the end face as in this example, a thinner active layer can be formed near the end face than inside the laser (d
, (d2).

As a result, in the vicinity of the end face, light widely spreads from the active layer 4 to the Crabstone layers (3 and 5), so the spot size of the laser increases and the optical output density decreases.

Therefore, the maximum optical output that causes end face destruction increases, making it possible to operate at higher output.

FIG. 2 shows a sectional view near the end face of the second embodiment. As can be seen from a comparison with FIG. 6, in the second embodiment, the depth of the groove between the ridges 7 is constant, and only the outer side of the ridge becomes deeper near the end face. The same effects as in the embodiment can be expected.

FIG. 3 shows a sectional view near the end face of the third embodiment. The third embodiment uses an n-type GaM S substrate 9 and has a structure in which current is injected from the Zn diffusion region 8 formed on the top of the active layer, but it is clear that the same effect as in the first embodiment is obtained. You can expect it.

Effects of the Invention As described above, the present invention provides a structure in which each layer including the active layer is written on a substrate on which two parallel ridges are written so that the height near the end face is high. The spot size is expanded and high output operation is possible.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of a first embodiment of the semiconductor laser device of the present invention, FIG. 2 is a structural cross-sectional view near the end face of the second embodiment of the semiconductor laser device of the present invention, and FIG. A structural sectional view near the end face of a third embodiment of the semiconductor laser device of the invention,
FIG. 4 is a diagram showing the middle of the manufacturing process of the first embodiment of the semiconductor laser device of the present invention, FIG. 6 is a sectional view near the end face of the first embodiment of the present invention, and FIG. FIG. 3 is an internal cross-sectional view of the laser of the first embodiment. 1... p-type GaAS substrate, 2... n-type GaAS layer, 3... pWGaA5As layer, 4...
...G & Murmu S active layer. Name of agent: Patent attorney Toshio Nakao and one other person
--pjihh base test

Claims (1)

[Claims] A semiconductor laser device in which a plurality of layers including an active layer are formed on a substrate in which two parallel ridges are formed higher near the laser end face than in the center.