Emitter and absorber assembly for multiple self-dual operation and directional transparency

TL;DR

This paper introduces a recursive design method for creating multi-frequency, self-dual emitter-absorber scatterers that can also achieve directional transparency, expanding capabilities beyond traditional symmetric setups.

Contribution

It presents a novel recursive assembly approach for non-Hermitian scatterers that operate as emitters and absorbers at multiple frequencies, allowing flexible and realistic configurations.

Findings

Design of multi-frequency emitter-absorber units demonstrated

Rearrangement of scatterers achieves unidirectional and bidirectional transparency

Applicable to wave scattering in single-channel systems with concrete photonic examples

Abstract

A recursive scheme for the design of scatterers acting simultaneously as emitters and absorbers, such as lasers and coherent perfect absorbers in optics, at multiple prescribed frequencies is proposed. The approach is based on the assembly of non-Hermitian emitter and absorber units into self-dual emitter-absorber trimers at different composition levels, exploiting the simple structure of the corresponding transfer matrices. In particular, lifting the restriction to parity-time-symmetric setups enables the realization of emitter and absorber action at distinct frequencies and provides flexibility in the choice of realistic parameters. We further show how the same assembled scatterers can be rearranged to produce unidirectional and bidirectional transparency at the selected frequencies. With the design procedure being generically applicable to wave scattering in single-channel settings, we demonstrate it with concrete examples of photonic multilayer setups.