Surface-emitting laser array, optical scanning device, and image forming device

Abstract

A surface-emitting laser array includes a plurality of surface-emitting laser elements. Each surface-emitting laser element includes a first reflection layer formed on a substrate, a resonator formed in contact with the first reflection layer and containing an active layer, and a second reflection layer formed over the first reflection layer and in contact with the resonator. The second reflection layer contains a selective oxidation layer. The first reflection layer contains on the active layer side at least a low refractive index layer having an oxidation rate equivalent to or larger than an oxidation rate of a selective oxidation layer contained in the second reflection layer. The resonator is made of an AlGaInPAs base material containing at least In. A bottom of a mesa structure is located under the selective oxidation layer and over the first reflection layer.

Description

TECHNICAL FIELD[0001]This invention relates to a surface-emitting laser array, an optical scanning device including the surface-emitting laser array, and an image forming device including the surface-emitting laser array.BACKGROUND ART[0002]In a surface-emitting laser array in which surface-emitting laser elements are integrated, the output of each surface-emitting laser element during operation may decline due to a temperature rise through reception of heat from the surrounding surface-emitting laser elements, and the life of the surface-emitting laser array may be shortened.[0003]To obviate the problem, it is necessary to improve the heat dissipation characteristic. For example, a material having a high thermal conductivity should be used for a semiconductor Bragg reflector which is located on the side of main heat dissipation. Among the materials which can be used for a semiconductor Bragg reflector of a surface-emitting laser element on a GaAs substrate, AlAs is a suitable one t...

AI Technical Summary

Benefits of technology

[0049]And in the process of forming the mesa structure, the difference between the etching depth in the array region where the surface-emitting laser elements are arranged and the etching depth in the circumference of the array region is reduced to prevent exposure of the first reflection layer in the circumference of the array region and prev...

Problems solved by technology

However, from the problem of the controllability of the etching depth, it is difficult to control the etching bottom to be deeper than the selective oxidation layer but not to reach the lower semiconductor Bragg reflector.

Practically, it is very difficult to carry out mesa etching so as be deeper than the selective oxidation layer but not to reach the lower semiconductor Bragg reflector.

However, in the case of the surface-emitting laser array, carrying out uniform mesa etching within the surface of the wafer is still more difficult for other additional reasons.

If the oxidation rate of the low refractive index layer of the lower semiconductor Bragg reflector is quicker than the selective oxidation layer, the whole low refractive index layer is oxidized early and performing the current pouring is impossible.

There are the problems that the optical output declines and the life of the surface-emitting laser elemen...

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