Temporal Switching to Extend the Bandwidth of Thin Absorbers

TL;DR

This paper introduces a formalism for temporal switching in thin absorbers, enabling broader bandwidths by reducing reflections, thus overcoming fundamental limits of traditional time-invariant passive structures.

Contribution

It extends quasi-normal mode theory to include time switching, providing a method to optimize switching strategies for enhanced broadband absorption.

Findings

Formalism models a wide class of time-switched structures

Optimal switching strategies maximize broadband minimal reflection

Promising applications in nanophotonics and metamaterials

Abstract

Wave absorption in time-invariant, passive thin films is fundamentally limited by a trade-off between bandwidth and overall thickness. In this work, we investigate the use of temporal switching to reduce signal reflections from a thin grounded slab over broader bandwidths. We extend quasi-normal mode theory to time switching, developing an ab initio formalism that can model a broad class of time-switched structures. Our formalism provides optimal switching strategies to maximize the bandwidth over which minimal reflection is achieved, showing promising prospects for time-switched nanophotonic and metamaterial systems to overcome the limits of time-invariant, passive structures.