A W-Band SPDT Photoconductive Evanescent-Mode Waveguide Switch

This letter presents the design, fabrication, and measurement of a silicon micromachined photoconductive evanescent (EVA)-mode waveguide switch operating in a single-pole double-throw (SPDT) configuration. Two EVA-mode waveguides loaded with silicon posts are placed in a Y configuration with a common feeding waveguide. In the absence of photoexcitation, the dielectric posts and EVA channel exhibit a bandpass filter response that allows low-loss propagation of signals on the order of 2.0 dB at 96.7 GHz. When photoexcited, the low conductive posts and EVA channel yield a very high isolation of 36.5 dB up to 102.4 GHz within $W$ -band. The proposed design shows promise for 5G and 6G communication backhaul devices.