JPH01136389A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To narrow an outgoing spread angle in the face direction, and to project beams to sections except the in-face direction by tapering a sectional shape along the axis of a pore reaching a striped active layer from the surface at an end section on the active layer side. CONSTITUTION:An active layer 12 is formed into a semiconductor clad layer 11 on a semiconductor substrate 10, and sectional shapes along the axes of pores 14 are formed to a tapered shape. Consequently, since tapered sections 21 in which end sections on the active layer 12 side of the pores 14 are formed to the tapered shape are shaped, emission from the active layer 12 is projected as face-direction outgoing beams 15 besides in-face outgoing beams 13. Since a semiconductor laser 16 can project beams within narrow ranges in the axial direction of the pores, a desired light-receiving section in another face type optical information processing element 17 arranged to an upper section can be irradiated with beams. Said pores 14 can be formed easily by a focussed ion beam device for an AuSiBe liquid metallic ion source.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a semiconductor laser used in optical communications and optical information processing.

(Prior Art and its Problems) The light emission direction of semiconductor lasers has become a problem in optical connections in optical communications and optical information processing. In particular, in order to improve the problem where electrical wiring is becoming impossible, solid-state optical information is used to process large amounts of information by arranging a large number of light sources, light receivers, etc. within a surface and connecting the surfaces with light. Processing elements are becoming important. In this solid-state optical information processing device, there is a need for a surface laser that can emit light in the direction connecting the surfaces and in the in-plane direction, and that can be integrated within the surface. Conventionally, the current situation is that very few such interview lasers have actually been manufactured. In other words, in contrast to existing lasers that emit light in the in-plane direction, true surface lasers with laser end faces in the plane are being developed, but the oscillation threshold current characteristics and reliability are still insufficient for integration. , there were problems such as not aiming to emit light in any direction other than perpendicular to the surface. Therefore, it is most practical to use an in-plane laser with excellent oscillation threshold current characteristics and reliability, but a surface laser with a 45° etching mirror near the laser end face is most practical. This was at a level that was previously known. A conventional example of a 45" etching mirror is described in Abride Physics Letters, 1985, Vol. 46, p. 115 (Z, L, Liau a
nd J., N., Walpole, Appl., Phy.
s, Lett.

115 (1985)). However, in the case of a semiconductor laser, the light is emitted radially from the laser end face around the optical axis, so a 45° etching mirror is not very effective.Especially in the direction perpendicular to the surface, the emission angle is large, so of the emitted light, There are many things that do not enter the mirror, and even if the reflected light does enter the mirror, it is scattered by the vertical wall surface, and the light is scattered in a direction other than the direction perpendicular to the desired surface.
There was a problem that the outgoing direction in the planar direction was wider than desired. Furthermore, it is desirable that the light source required for the solid-state optical information processing device described above should be able to narrow the light emission direction to some extent when connecting surfaces with light, and if possible, be able to emit light in multiple directions from one laser. However, a semiconductor laser with such a structure has not been known so far.

Therefore, an object of the present invention is to improve the problems of the above-mentioned conventional elements, and to make it possible to emit light not only in the in-plane direction of the active layer but also in the direction at an angle to the active layer surface (in-plane direction). The emission spread angle in the in-plane direction is narrow, and at least 1 in the in-plane direction
It is an object of the present invention to provide a semiconductor laser that can emit light in more than one direction, that is, can easily connect optically in directions other than the in-plane direction, and is therefore suitable for a solid-state optical information processing device.

(Means for Solving the Problems) Means provided by the present invention in order to solve the above-mentioned problems and achieve the above objects is a semiconductor laser having a striped active layer in a layered semiconductor on a semiconductor substrate. at least one pore reaching the striped active layer from the surface of the semiconductor laser, and a cross-sectional shape along the axis of the pore is tapered at an end on the active layer side. It is characterized by a tapered tip.

(Principle of Operation of the Invention) In the semiconductor laser of the present invention, emitted light originally in the in-plane direction is directed in the in-plane direction by utilizing reflection and scattering by the semiconductor. FIG. 1 is a schematic perspective view showing a semiconductor laser according to an embodiment of the present invention, and the principle of operation of the present invention will be explained below as an example with reference to this figure.

The semiconductor laser of the present invention has an active layer 12 provided in a semiconductor cladding layer 11 on a semiconductor substrate 10, and has the same layer structure as a normal semiconductor laser. However, the semiconductor laser of the present invention is different from the conventional semiconductor laser in that at least one pore 14 reaching the active layer 12 from the element surface is provided. Since the pores 14 are provided, the light emitted from the active layer 12 is
The semiconductor laser 16 of the present invention, which can emit in-plane emitted light 15 as well as in-plane emitted light 15, can emit light within a narrow range in the axial direction of the pore. It becomes possible to irradiate light to a desired light receiving portion of the optical information processing element 17.

In the structure of the present invention, the light emitted from the active layer 12 is transmitted through the pores 14.
As a device to guide the light in a narrow direction along the axis of the pore 14 and emit it to the outside, the cross-sectional shape of the pore 14 along the axis is tapered to a narrow point, as shown in the cross-sectional view in Fig. 2. . Second
As shown in the figure, by providing a tapered portion 21 in which the end of the pore 14 on the active layer 12 side is tapered, it is possible to achieve high light extraction efficiency and in-plane light emission with a narrow light spread. .

Embodiments of the present invention will be described in more detail below.

(Example) As described above, FIG. 1 is a schematic perspective view showing an example of the present invention. In this example, a cladding layer 11 and stripes are formed on a substrate 10 according to a normal semiconductor laser manufacturing process. After the striped active layer 12 was formed, pores 14 reaching desired portions of the striped active layer 12 were formed using a focused ion beam device. The tips of the pores 14 on the side of the active layer 12 are tapered.
．． Penetrates through 5-thick p-type AQGaAs cladding layer 0.
Pore 1 reaching GaAs active layer 12 of IJIfll
No. 4 was formed by etching with an Au ion beam having a beam diameter of 0.4 - using a focused ion beam device with an Au5iBe liquid metal ion source. In the 0-line etching method in which the inner diameter of the pores 14 is set to 1- on the surface side, there is a phenomenon in which the etching material re-attaches to the pore walls, so it is easy to form the pores 14 that taper at the tip. Can be done.

The axial direction of the pores 14 is not uniform as shown in FIG. There are some things.

Electrodes were provided on the device formed in this way, the semiconductor laser was completed, and as a result of energization, the oscillation current characteristics were almost the same as the conventional device, and the beam in the in-plane direction was found to be smaller than that of the conventional solid-state light-emitting laser using an etching mirror. Output light with a narrow spread was obtained. Furthermore, the light can be efficiently emitted to the light-receiving elements arranged in a plane above this element, providing a clue to the realization of a plane-type optical information processing element.

The above embodiment is based on GaAQAs/GaAs, but In
A similar element can be formed in the P/InGaAsP system, and the method for forming the pores is not necessarily limited to focused ion beam, but may be formed by other methods.
It is also useful to coat the pore walls with a metal film to increase the reflectance of the pore walls. In the case of the above example,
By lowering the Au focused ion beam incident voltage,
A coating of Au film was formed, which resulted in better light output efficiency.

(Effects of the Invention) As explained above, the semiconductor laser of the present invention has a narrower emission spread angle in the plane direction than that of a conventional solid-state laser element using an etching mirror, and can also emit light in multiple directions. . Therefore, the semiconductor laser of the present invention allows easy optical connection in directions other than the in-plane direction, and is therefore a device suitable for solid-state optical information processing.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing one embodiment of the present invention, and FIG.
The figure is an enlarged sectional view of a portion including the pores 14 of the embodiment in FIG. DESCRIPTION OF SYMBOLS 10... Substrate, 11... Clad layer, 12... Active layer, 13... In-plane emitted light, 14... Pore, 15...
... Planar direction emitted light, 17... Other planar optical information processing element, 21... Tapered portion.

Claims (1)

[Claims] In a semiconductor laser having a striped active layer in a layered semiconductor on a semiconductor substrate, at least one layer reaching the striped active layer from the surface of the semiconductor laser.
What is claimed is: 1. A semiconductor laser comprising a plurality of pores, and a cross-sectional shape of the pores along an axis thereof tapers at an end on the active layer side.