Optically Controlled Tunable and Reconfigurable Terahertz Devices

Tunable and reconfigurable terahertz (THz) devices such as modulators/variable attenuators, tunable filters, coded apertures, phase shifters and high-level switches (e.g., DPDT) that are required for advanced imaging and adaptive wireless communication applications are challenging to realize. We report a promising approach to develop the above THz devices based on spatially-resolved optical modulation (SROM) using photo-induced (PI) free carriers in semiconductors. The fundamental mechanism for this approach will first be introduced followed by prototype demonstrations for reconfigurable coded-aperture imaging masks, beam steering/forming antennas and waveguide-based tunable attenuators. The potential to develop more advanced tunable/reconfigurable THz devices (e.g., tunable delay lines, SPDT, DPDT switches) using optically-controlled waveguide architectures such as PI electromagnetic band gap (EBG) structures and dynamically-reconfigurable PI substrate-integrated waveguides (SIWs) will also be discussed on the basis of performance-improved SROM using the so-called mesa-array technique.