Development of Optically Controlled Tunable/Reconfigurable Terahertz Waveguide Circuits/Components For Advanced Sensing and Adaptive Wireless Communications

We report our recent progress toward the development of optically controlled tunable/reconfigurable THz circuits/components in waveguide configurations for advanced sensing and adaptive wireless communications. The development and demonstration of a modified WR-4.3 variable waveguide attenuator based on photo-excited Si with 60-dB range and 0.7-dB insertion loss will first be reviewed. Then the investigation of a WR-5.1 reconfigurable band-stop filter (BSF) prototype based on photo-induced electromagnetic band gap (PI-EBG) structures using semiconductor mesa arrays will be presented. The center frequency of the BSF can be reconfigured from 166-200 GHz with adjustable stop-band rejection and bandwidth. Finally, the development of high-performance THz integrated switches using the same optical control methodology enabling the implementation of more advanced tunable/reconfigurable THz waveguide circuits will be envisioned, investigated and discussed. Preliminary results reveal that the optically controlled RF switches show a potentially record-high figure-of-merit (evaluated by R
_on
C
_off
constant) of 153 THz, allowing them to outperform both conventional solid-state-device-based (e.g., HEMTs) and emerging phase-changing-material-based (e.g., VO
₂
) counterparts, and therefore promising to compete with MEMS switches in the mmW-THz region for a novel class of tunable/reconfigurable circuits/components.