Spatiotemporal manipulation of electromagnetic waves has recently enabled a new world of exotic optical functionalities, such as non-reciprocity, dynamic wavefront control, unidirectional transmission, linear frequency conversion and electromagnetic Doppler cloak. We introduce an additional dimension for advanced manipulation of terahertz waves in the space-time, and frequency domains through integration of spatially reconfigurable microelectromechanical systems with photoresponsive material platform. A large and continuous frequency agility is achieved through movable microcantilevers. The ultrafast resonance modulation occurs upon photoexcitation of ion-irradiated silicon substrate that hosts the microcantilever metamaterial. The fabricated metamaterial switches in 400 ps and provides large spectral tunability of 250 GHz with 100% resonance modulation at each frequency. The integration of perfectly complementing technologies of microelectromechanical systems, femtosecond optical control and ion-irradiation offer unprecedented concurrent control over space, time and frequency response of metamaterial for designing frequency-agile spatiotemporal modulators, active beamforming and low-power frequency converters for the next generation terahertz wireless communications.
The authors acknowledge the research funding support from National Research Foundation
(NRF) Singapore and Agence Nationale de la Recherche (ANR), France- NRF2016- ANR004
(M4197003), NRF CRP on Oxide Electronics on silicon Beyond Moore (NRF-CRP15-2015-
01) and Advanced Manufacturing and Engineering (AME) Programmatic grant (A18A5b0056)
from Agency for Science, Technology and Research (A*STAR).