Unidirectional perfect reflection and radiation in double-lattice photonic crystals

TL;DR

This paper demonstrates a novel unidirectional photonic device using a double-lattice photonic crystal that achieves perfect radiation or reflection depending on the incident direction, based solely on radiation effects.

Contribution

It introduces a new design for unidirectional photonic behavior utilizing radiation in a double-lattice photonic crystal with a single exceptional point, without relying on material loss or gain.

Findings

Achieved unidirectional perfect radiation and reflection.

Demonstrated experimental realization of the concept.

Showed potential for new non-Hermitian photonic applications.

Abstract

Non-Hermitian photonic systems are known to exhibit unique phenomena, where non-Hermiticity is typically introduced by material loss or gain. Here, we propose and experimentally demonstrate unidirectional phenomena solely based on radiation. Our design is on the basis of a double-lattice photonic crystal that has a linear dispersion with a single exceptional point, where the magnitudes of Hermitian and non-Hermitian couplings are cancelled out in one direction. Based on this concept, we realize a unidirectional waveguide which shows perfect radiation when light is incident from one side, and shows perfect reflection when light is incident from the other side. Our results will open up a new route toward harnessing non-Hermiticity.