In this paper, we provide a comprehensive review of unidirectional reflectionless light
propagation in photonic devices at exceptional points (EPs). EPs, which are branch point …

We analyze chiral topological edge modes in a non-Hermitian variant of the 2D Dirac
equation. Such modes appear at interfaces between media with different “masses” and/or …

Compound-photonic structures with gain and loss provide a powerful platform for testing
various theoretical proposals on non-Hermitian parity–time-symmetric quantum mechanics …

Higher-order topology realizes topologically robust corner modes as a manifestation of
nontriviality. We theoretically propose non-Hermitian skin effects which stem from the …

In 1832 Hamilton predicted that a collimated light beam propagating through a biaxial crystal
parallel to one of its optical axes refracts as a slanted cone within the crystal and emerges as …

The recently developed notion of parity–time (PT) symmetry in optical systems has spawned
intriguing prospects. So far, most experimental implementations have been reported in solid …

We study a topological band degeneracy in non-Hermitian systems with parity-time (PT) and
parity-particle-hole (CP) symmetries. In d-dimensional non-Hermitian systems, it is shown …

We show that topologically protected defect states can exist in open (leaky or lossy) systems
even when these systems are topologically trivial in the closed limit. The states appear from …

We formulate and exploit a computational inverse-design method based on topology
optimization to demonstrate photonic crystal structures supporting complex spectral …

A mechanism for asymmetric transport which is based on parity-time-symmetric
nonlinearities is presented. We show that in contrast to the case of conservative …