Semiconductor optical modulator, an optical amplifier and an integrated semiconductor light-emitting device

Abstract

An integrated semiconductor optical-emitting device includes a surface-emission laser diode and an EA-type semiconductor optical modulator integrated commonly on a GaAs substrate in a direction perpendicular to the GaAs substrate.

Description

BACKGROUND OF THE INVENTION [0001] The present invention generally relates to optical semiconductor devices. Especially, it is related to optical semiconductor devices such as a semiconductor optical modulator, a semiconductor light-emitting device, a semiconductor optical amplifier, an optical source of amplitude spontaneous emission (ASE), an optical gate array, a tunable laser apparatus, a multi-wavelength laser apparatus, and also an optical transmission system that uses such an optical semiconductor device. Further, the present invention relates to the fabrication process of the optical semiconductor devices. [0002] Japanese Laid-Open Patent Publication 10-22805 describes a semiconductor optical modulator that uses an InGaAsP multiple quantum well structure. In this reference, an InP / InGaAsP multiple quantum well structure is used as an optical modulator, and optical modulation is achieved by causing quantum confinement Stark effect in the multiple quantum well structure. In qu...

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Benefits of technology

[0012] Accordingly, it is a general object of the present invention to provide a novel and useful optical semiconductor device and a fabrication pro

Problems solved by technology

However, conventional EA-type semiconductor optical modulator that uses the InP / InGaAsP multiple quantum well structure has a drawback, due to the relatively small conduction band discontinuity between the InP barrier layer and the InGaAsP quantum well layer, in that the excitons are tend to be destroyed due to the leakage of electrons from the quantum well layer upon application of the voltage to the quantum well layer, wherein this problem becomes particularly serious when operating the EA modulator at high temperatures.

As a result, there arises a problem of severe degradation of S / N ratio of optical modulation.

In such a system, however, there arises a problem similar to the case of the EA-type optical modulator in that, because of the relatively small conduction band discontinuity between the InGaAsP layer acting as the gain region and the InP layer acting as a carrier-blocking layer of 150-200 meV, and further in view of the Auger non-optical recombination effect, and the like, the electrons easily cause leakage from the gain region.

The problem of electron leakage becomes particularly serious at high temperatures.

The same tendency applies also to the case of the semiconductor optical amplifier, and thus, there is a tendency that optical amplification causes saturation at high temperatures as a result of the leakage of carriers from the gain region.

As a result of such a carrier leakage, it has been difficult to achieve a large optical amplification factor in the conventional semiconductor optical amplifiers particularly at high temperatures.

Thus, this problem has been a bottleneck when constructing a low-cost optical LAN system that requires semiconductor optical amplifiers without using an electronic cooling system.

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