Photo-Induced Coplanar Waveguide RF Switch and Optical Crosstalk on High-Resistivity Silicon Trap-Rich Passivated Substrate

A continuous-wave mode optically controlled coplanar waveguide radio frequency (RF) switch on high-resistivity silicon substrate with and without trap-rich polysilicon (poly-Si) layer is investigated. Because of the local poly-Si trap-rich layer, we experimentally show the important reduction of optical crosstalk without degrading the photo-controlled RF switch performance. A photo-induced plasma confinement by locally etching the poly-Si layer to control the photogenerated free carriers and their lateral diffusion is realized. Optical crosstalk between two coplanar waveguide RF switches is reduced by at 20 GHz.