Electromechanically Tunable Metasurface Transmission Waveplate at Terahertz Frequencies

TL;DR

This paper introduces a reconfigurable terahertz metasurface quarter-waveplate that uses electromechanical actuation of micro-cantilevers to dynamically control polarization states, enabling real-time polarization tuning for terahertz applications.

Contribution

It presents a novel, CMOS-compatible, electromechanically tunable metasurface device capable of real-time polarization control at terahertz frequencies, fabricated via surface micromachining.

Findings

Achieved a ~230 GHz resonance frequency shift through cantilever actuation.

Demonstrated modulation of transmitted light from circular to linear polarization.

Fabricated and characterized the device using terahertz time domain spectroscopy.

Abstract

Dynamic polarization control of light is essential for numerous applications ranging from enhanced imaging to materials characterization and identification. We present a reconfigurable terahertz metasurface quarter-waveplate consisting of electromechanically actuated micro-cantilever arrays. Our anisotropic metasurface enables tunable polarization conversion cantilever actuation. Specifically, voltage-based actuation provides mode selective control of the resonance frequency, enabling real-time tuning of the polarization state of the transmitted light. The polarization tunable metasurface has been fabricated using surface micromachining and characterized using terahertz time domain spectroscopy. We observe a ~230 GHz cantilever actuated frequency shift of the resonance mode, sufficient to modulate the transmitted wave from pure circular polarization to linear polarization. Our CMOS-compatible tunable quarter-waveplate enriches the library of terahertz optical components, thereby facilitating practical applications of terahertz technologies.