OPTICAL SEMICONDUCTOR ELEMENT

摘要

PURPOSE:To make possible the mass production with high production accuracy by forming an optical waveguide region of mixed crystals composed of Si and Ge on an Si substrate. CONSTITUTION:Grooves 4 are formed to the places to be formed as the optical waveguide region on the surface of the n type Si substrate 1 and the mixed crystals Si1-x Gex 2 composed of Si and Ge and Si 3 of n<-> type are laminated thereon. The spacing between the two grooves 4 is adequately set so that the light conducted by the grooves 4 is transferred from one to the other groove 4. The directional coupler is thus constituted. The refractive index is changed by a plasma oscillation effect when the modulating current is injected from a modulating signal source 7 through the electrode 5 and the p type Si region 8 to the Si1-xGex layer 2 between the groove 4 and the groove 4. Since the coupling constant between the two optical waveguide regions 9 changes, the conductive light is subjected to the modulation. More specifically, the Si substrate for which the process technology is extremely advanced is used and therefore the inexpensive and precision mass production is made possible. Electronic circuits are integrated on the same Si substrates and the application to an optical exchange is possible by the large-scale integrated optical switches.