Flexible terahertz metasurface absorbers empowered by bound states in the continuum

TL;DR

This paper introduces a flexible, tunable terahertz metasurface absorber leveraging bound states in the continuum (BICs) to achieve customizable absorption properties suitable for advanced optical and photonic applications.

Contribution

It demonstrates a novel approach to designing terahertz absorbers with adjustable performance using BICs, enabling multi-band, wide field of view, and tunable bandwidth functionalities.

Findings

Achieved perfect absorption with BICs in terahertz metasurfaces.

Demonstrated tunable bandwidth and multi-band absorption.

Provided a systematic design approach based on symmetry and topological analysis.

Abstract

Terahertz absorbers are crucial to the cutting-edge techniques in the next-generation wireless communications, imaging, sensing, and radar stealth, as they fundamentally determine the performance of detectors and cloaking capabilities. It has long been a pressing task to find absorbers with customizable performance that can adapt to various environments with low cost and great flexibility. Here, we demonstrate perfect absorption empowered by bound states in the continuum (BICs) allowing for the tailoring of absorption coefficient, bandwidth, and field of view. The one-port absorbers are interpreted using temporal coupled-mode theory highlighting the dominant role of BICs in the far-field radiation properties. Through a thorough investigation of BICs from the perspective of lattice symmetry, we unravel the radiation features of three BIC modes using both multipolar and topological analysis. The versatile radiation capabilities of BICs provide ample freedom to meet specific requirements of absorbers, including tunable bandwidth, stable performance in a large field of view, and multi-band absorption using a thin and flexible film without extreme geometric demands. Our findings offer a systematic approach to developing optoelectronic devices and demonstrate the significant potential of BICs for optical and photonic applications which will stimulate further studies on terahertz photonics and metasurfaces.