Dynamically reversible and strong circular dichroism based on Babinet-invertible chiral metasurfaces

TL;DR

This paper introduces a Babinet-invertible chiral metasurface using VO$_2$-metal hybrid structures that enables large, reversible circular dichroism tuning at THz frequencies, advancing active chiro-optical device engineering.

Contribution

It presents a novel VO$_2$-based metasurface that achieves dynamically reversible and strong circular dichroism through Babinet principle-based switching.

Findings

Achieves CD tuning range of ±0.5 at 0.97 THz, larger than previous work.

Uses VO$_2$ phase transition to switch metasurface structures.

Demonstrates potential for active, tunable chiro-optical devices.

Abstract

We propose a Babinet-invertible chiral metasurface for achieving dynamically reversible and strong circular dichroism (CD). The proposed metasurface is composed of VO$_2$-metal hybrid structure, and when VO$_2$ transits between the dielectric state and the metallic state, the metasurface unit cell switches between complementary structures that are designed according to the Babinet principle. This leads to a large and reversible CD tuning range between $\pm 0.5$ at 0.97~THz, which is larger than the literature. We attribute the CD effect to extrinsic chirality of the proposed metasurface. We envision that the Babinet-invertible chiral metasurface proposed here will advance the engineering of active and tunable chiro-optical devices and promote their applications.