Broadband and energy-concentrating terahertz coherent perfect absorber based on a self-complementary metasurface

TL;DR

This paper introduces a broadband, energy-concentrating terahertz coherent perfect absorber based on a self-complementary metasurface, demonstrating both theoretical and experimental success in achieving subwavelength energy absorption.

Contribution

It presents a novel self-complementary metasurface design that functions as a broadband, subwavelength coherent perfect absorber in the terahertz regime, with experimental validation.

Findings

Achieves broadband absorption below diffraction frequency

Demonstrates energy concentration at deep-subwavelength scale

Validates design through terahertz time-domain spectroscopy

Abstract

We demonstrate that a self-complementary checkerboard-like metasurface works as a broadband coherent perfect absorber (CPA) when symmetrically illuminated by two counter-propagating incident waves. A theoretical analysis based on wave interference and results of numerical simulations of the proposed metasurface are provided. In addition, we experimentally demonstrate the proposed CPA in the terahertz regime by using a time-domain spectroscopy technique. We observe that the metasurface can work as a CPA below its lowest diffraction frequency. The size of the absorptive areas of the proposed CPA can be much smaller than the incident wavelength. Unlike conventional CPAs, the presented one simultaneously achieves the broadband operation and energy concentration of electromagnetic waves at the deep-subwavelength scale.