Extremely asymmetric absorption and reflection near the exceptional point of three-dimensional metamaterial

TL;DR

This paper demonstrates a 3D non-Hermitian metamaterial with engineered losses that exhibits highly asymmetric absorption and reflection near the exceptional point, with potential applications in perfect absorption and sensing.

Contribution

The study introduces a loss-assisted 3D metamaterial design with experimentally observed asymmetric absorption and reflection near the exceptional point, linking circuit models with quantum physical models.

Findings

Experimental demonstration of asymmetric absorption and reflection near EP

Tuning of loss and circuit parameters controls EP response

Potential for designing advanced absorbers and sensors

Abstract

In recent years, particular physical phenomena enabled by non-Hermitian metamaterial systems have attracted significant research interests. In this paper, a non-Hermitian three-dimensional metamaterial near the exceptional point (EP) is proposed to demonstrate extremely asymmetric absorption and reflection. Unlike its conventional counterparts, this proposed metamaterial is constructed with a loss-assisted design. Localized losses are introduced into the structure by combining our technique of graphene-based resistive inks with conventional printed circuit board (PCB) process. Extremely asymmetric absorption and reflection near the EP are experimentally observed by tuning the loss between split ring resonators (SRRs) in the meta-atoms. Simultaneously, by linking the equivalent circuit model (ECM) with the Hamiltonian quantum physical model, the equivalent non-Hermitian Hamiltonian is obtained and a non-Hermitian transmission matrix is constructed. We show that tuning the structure and circuit parameters of the ECM produces a metamaterial system with EP response. Our system can be used in the design of asymmetric metamaterial absorbers. Our work lays down the way for the manipulation of EP to develop perfect absorption, sensing and other applications in the 3D metamaterial platform.