High extinction guided-wave optical polarization splitter

Conventional guided-wave optical polarization splitters exhibit poor polarization extinction characteristics because of the necessity of controlling waveguide parameters. In order to improve the characteristics, an electrical control scheme was investigated in an alternating Δβ 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. This is the highest value ever reported with a channel waveguide device