Broadband operation of active terahertz quarter-wave plate achieved with vanadium-dioxide-based metasurface switchable by current injection

TL;DR

This paper presents a broadband, switchable terahertz quarter-wave plate using vanadium dioxide metasurface with anisotropic structures, enabling deep modulation and helicity switching near 0.66THz, with significantly increased bandwidth.

Contribution

It introduces a novel broadband, switchable terahertz waveplate based on vanadium dioxide metasurface with anisotropic deformation, surpassing previous bandwidth limitations.

Findings

Achieved helicity switching of circularly polarized waves at 0.66THz

Demonstrated a relative bandwidth of 0.52, 4.2 times broader than prior work

Integrated current injection circuit for state monitoring and switching

Abstract

We demonstrate the broadband operation of a switchable terahertz quarter-wave plate achieved with an active metasurface employing vanadium dioxide. For this purpose, we utilize anisotropically deformed checkerboard structures, which present broadband characteristics compatible with deep modulation. Moreover, the metasurface is integrated with a current injection circuit to achieve state switching; this injection circuit can also be employed to monitor the electric state of vanadium dioxide. We estimate the Stokes parameters derived from the experimental transmission spectra of the fabricated metasurface and confirm the helicity switching of circularly polarized waves near a designed frequency of 0.66THz. The relative bandwidth is evaluated as 0.52, which is 4.2 times broader than that in a previous study.