Wavefront Shaping with a Tunable Metasurface: Creating Coldspots and Coherent Perfect Absorption at Arbitrary Frequencies

TL;DR

This paper demonstrates how a tunable programmable metasurface can dynamically control electromagnetic waves inside a cavity, enabling creation of nulls and perfect absorption at arbitrary frequencies, enhancing electromagnetic system robustness.

Contribution

It introduces a novel optimization algorithm for wave control using a programmable metasurface, achieving nulls and perfect absorption across multiple frequencies and configurations.

Findings

Successful creation of transmission nulls at arbitrary frequencies.

Effective multi-band optimization with various port configurations.

Establishment of multi-port coherent perfect absorption states.

Abstract

Modern electronic systems operate in complex electromagnetic environments and must handle noise and unwanted coupling. The capability to isolate or reject unwanted signals for mitigating vulnerabilities is critical in any practical application. In this work, we describe the use of a binary programmable metasurface to (i) control the spatial degrees of freedom for waves propagating inside an electromagnetic cavity and demonstrate the ability to create nulls in the transmission coefficient between selected ports; and (ii) create the conditions for coherent perfect absorption. Both objectives are performed at arbitrary frequencies. In the first case a novel and effective optimization algorithm is presented that selectively generates coldspots over a single frequency band or simultaneously over multiple frequency bands. We show that this algorithm is successful with multiple input port configurations and varying optimization bandwidths. In the second case we establish how this technique can be used to establish a multi-port coherent perfect absorption state for the cavity.