Optical switching device

Abstract

Disclosed is an optical switch device for totally reflecting an incident light therein in accordance with a change in refractive index occurring owing to current application, which is manufactured by the steps of: sequentially forming an optical waveguide layer, an n-InP clad layer and an n-InGaAs cap layer on a main surface of an n-InP substrate using an epitaxial growing; selectively etching the n-InGaAs cap layer to form an opening tapered downward; diffusing an impurity into the n-InP clad layer through the opening and into the n-InGaAs cap layer to a predetermined depth from a surface thereof so as to form a first impurity diffused region in the n-InP clad layer under the opening and to form a second impurity diffused region along the surface of the n-InGaAs cap layer; etching the layers on the optical waveguide layer using a mask to form a ridge-shaped waveguide; and forming electrodes on the n-InGaAs cap layer and an exposed surface of the n-InP clad layer and on a surface which is opposite to the main surface of the n-InP substrate. Also, before forming the n-InGaAs cap layer, a p-InP current blocking layer is formed between the n-InP clad layer and the n-InGaAs cap layer so as to prevent a current from being dispersed other portions excluding the impurity diffused portion.