Dynamic Switching between Surface Wave and Plane Wave with MEMS-based Metasurface*

We present polarization-insensitive dynamic surface wave (SW) switching at terahertz frequencies utilizing a MEMS-based metasurface. Our MEMS-based metasurface consists of a micro-cantilever array, enabling dynamic tuning between a plane wave (PW) and a SW for normal incidence of terahertz radiation. Through individual control of the driving voltages on the cantilever unit cells, we achieve nearly 2π phase modulation with minimal reflection amplitude modulation. Coupled mode theory (CMT) is employed to design the metasurface device and agrees with full-wave electromagnetic simulations. Our demonstration paves the road for terahertz multifunctional metasurface devices for spatial light modulation, dynamic beam steering, focusing, and beam coupling.