Polarization Independent GaAs/AlGaAs Electro-Optic Guided-Wave Directional Coupler Switch Using (111)-Oriented GaAs Substrate

Abstract

The interest in guided-wave optical switches made of III-V semiconductor compounds for photonic switching application is growing, because of their large scale integration capability and their ability to be integrated with other semiconductor devices. Therefore, several kinds of optical switch, such as a carrier injection type switch[1], a gain guide type switch[2] and a directional coupler type switch[3], have been investigated. Among them, a GaAs/AlGaAs electro-optic directional coupler (EODC) is attractive, because of its low absorption loss at long wavelength region[4], fast switching speed, low electric power consumption and wavelength independent operation capability. Therefore, a GaAs/AlGaAs EODC is promising as a cross-point element in an integrated matrix switch. Actually, 4×4 GaAs/AlGaAs matrix switches with quite uniform device characteristics have already been realized[5] by the authors. However, all of reported semiconductor directional coupler switches, so far using electro-optic effect, have been polarization sensitive. Polarization independent semiconductor EODCs, compatible with standard single-mode fibers, are desired for practical use. Although some polarization independent LiNbO3 switches have been recently reported[6],[7], no attempt to realize polarization independent semiconductor EODC has been made yet.