Abstract

We consider the interaction of a short optical pulse with a layer with periodically modulated permittivity and a periodic gain-and-loss landscape. It is found that if the medium is quasi-parity-time ($\mathcal{PT}$)-symmetric in the vicinity of the exceptional point, the propagation manifests strong unidirectional reflection and invisibility. Due to strong frequency selectivity, quasi-$\mathcal{PT}$-symmetric periodic layers manifest efficient filtering of back-radiation.

© 2019 Optical Society of America

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