Reflectionless and invisible potentials in photonic lattices

TL;DR

This paper demonstrates that certain drifting optical potentials in photonic lattices are inherently reflectionless and invisible due to the lattice's discrete symmetry, revealing unique scattering properties not found in continuous media.

Contribution

It introduces the concept of reflectionless and invisible potentials in discrete photonic lattices, highlighting effects arising from lattice symmetry and non-Hermitian properties.

Findings

Drifting potentials faster than the light cone are reflectionless.

Kramers-Kronig type potentials are invisible in drifting conditions.

Discrete symmetry leads to unique scattering phenomena.

Abstract

An arbitrarily-shaped optical potential on a discrete photonic lattice, which transversely drifts at a speed larger than the maximum one allowed by the light cone of the lattice band, becomes reflectionless. Such an intriguing result, which arises from the discrete translational symmetry of the lattice, is peculiar to discretized light and does not have any counterpart for light scattering in continuous optical media. A drifting non-Hermitian optical potential of the Kramers-Kronig type is also an invisible potential, i.e. a discrete optical beam crosses the drifting potential without being distorted, delayed nor advanced.