HIGH EXTINCTION GUIDED-WAVE OPTICAL POLARIZATION SPLITTER

A conventional guided-wave optical polarization splitter was poor in the polarization extinction characteristics because of the necessity of the stringent waveguide parameter control. In order to improve the characteristics, we investigated a novel electrical control scheme in an alternating DELTA-beta directional coupler. Polarization dependent electrooptic as well as polarization independent plasma effects were employed to produce high extinction for two orthogonal polarizations independently. As a result, an extinction ratio as high as 32 dB was obtained with a fabricated GaAs-GaAlAs device. To our knowledge, this is the highest value ever reported with a channel waveguide device.