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

摘要

A recursive scheme for the design of scatterers acting simultaneously asemitters and absorbers, such as lasers and coherent perfect absorbers inoptics, at multiple prescribed frequencies is proposed. The approach is basedon the assembly of non-Hermitian emitter and absorber units into self-dualemitter-absorber trimers at different composition levels, exploiting the simplestructure of the corresponding transfer matrices. In particular, lifting therestriction to parity-time-symmetric setups enables the realization of emitterand absorber action at distinct frequencies and provides flexibility in thechoice of realistic parameters. We further show how the same assembledscatterers can be rearranged to produce unidirectional and bidirectionaltransparency at the selected frequencies. With the design procedure beinggenerically applicable to wave scattering in single-channel settings, wedemonstrate it with concrete examples of photonic multilayer setups.