Coherent Asymmetric Absorbers

TL;DR

This paper introduces a novel concept of a coherently-illuminated, space-modulated metasurface that acts as an asymmetric absorber, enabling advanced control of electromagnetic waves for sensing applications.

Contribution

It proposes a new type of coherent asymmetric absorber using space-modulated metasurfaces, extending control beyond uniform metasurfaces and addressing non-ideal illumination conditions.

Findings

Demonstrates the feasibility of space-modulated metasurfaces as asymmetric absorbers.

Analyzes behavior under non-ideal illumination conditions.

Suggests potential sensing applications.

Abstract

Most applications of metasurfaces require excitation and control of both electric and magnetic surface currents. For such purpose, the metasurface must have a finite thickness to handle magnetic surface currents. For metasurface sheets of negligible thickness that offer only electric response, coherent illumination can compensate the need to create discontinuities of the tangential electric field component using magnetic surface currents. Most of known coherent metasurfaces are space-uniform and can control only plane-wave absorption and specular reflection. However, it is also known that periodical space-modulated (inhomogeneous) metasurfaces can be used to realize anomalous reflection, refraction, and other useful effects. In this paper, we propose the concept of a coherently-illuminated space-modulated metasurface that functions as a coherent asymmetric absorber. We study its behaviour under non-ideal illuminations and suggest applications related with sensing.