Room-Temperature Anisotropic Plasma Mirror and Polarization-Controlled Optical Switch Based on Type-II Weyl Semimetal WP2

TL;DR

This paper reports the discovery of a room-temperature anisotropic plasma mirror in WP2, enabling polarization-controlled optical switching and potential applications in multifunctional topological optical devices.

Contribution

It introduces the first room-temperature anisotropic plasma mirror in a Weyl semimetal and demonstrates a polarization-controlled optical switch based on WP2.

Findings

Anisotropic plasma reflectance edge observed in WP2 with a ratio of 1.5.

Room-temperature polarization-sensitive optical switching achieved.

Robustness of plasma mirror behavior across a wide temperature range.

Abstract

Anisotropy in electronic structures may ignite intriguing anisotropic optical responses, as has been well demonstrated in various systems including superconductors, semiconductors, and even topological Weyl semimetals. Meanwhile, it is well established in metal optics that the metal reflectance declines from one to zero when the photon frequency is above the plasma frequency {\omega}p , behaving as a plasma mirror. However, the exploration of anisotropic plasma mirrors and corresponding applications remains elusive, especially at room temperature. Here, we discover a pronounced anisotropic plasma reflectance edge in the type-II Weyl semimetal WP2, with an anisotropy ratio of {\omega}p up to 1.5. Such anisotropic plasma mirror behavior and its robustness against temperature promise optical device applications over a wide temperature range. For example, the high sensitivity of polarization-resolved plasma reflectance edge renders WP2 an inherent polarization detector. We further achieve a room-temperature WP2-based optical switch, effectively controlled by simply tuning the light polarization. These findings extend the frontiers of metal optics as a discipline and promise the design of multifunctional devices combining both topological and optical features.