Polarization-controlled non-Hermitian metasurfaces for ultra-sensitive terahertz sensing

TL;DR

This paper introduces a polarization-controlled non-Hermitian metasurface sensor that enhances robustness and sensitivity in terahertz sensing by leveraging polarization degrees of freedom, addressing fabrication and noise challenges near exceptional points.

Contribution

The work presents a novel polarization-based approach to control phase singularities in non-Hermitian metasurfaces, improving sensor robustness and sensitivity in the terahertz regime.

Findings

Theoretical relation between incident polarization and transmission phase was established.

Experimental validation demonstrated enhanced robustness and sensitivity.

Polarization angle serves as an effective sensing index.

Abstract

Non-Hermitian systems offer significant advantages in sensor design, especially at the exceptional points. However, the extreme sensitivity near these points poses great challenges due to fabrication errors and system noises, which degrade sensing performance. To address this, we introduce a novel approach leveraging the polarization degrees of freedom in non-Hermitian systems. In this work, we establish a direct relation between the incident polarization and the transmission phase of a coupled metasurface system and achieve the polarization-controlled phase singularity even post-fabrication. The incident polarization angle can be utilized as a sensing index, which enables indirect and accurate measurement. The theoretical approach is experimentally validated using a general design of THz non-Hermitian metasurface sensors. Our method enhances robustness and sensitivity, opening new avenues for practical applications in ultra-sensitive sensing.