Non-diffracting states at exceptional points

TL;DR

This paper explores the use of exceptional points in photonic lattices to achieve diffraction-free beam propagation, localized power oscillations, and robust orbital angular momentum beams, expanding the applications of EPs in photonics.

Contribution

It introduces two novel systems utilizing exceptional points for stable OAM beam propagation and demonstrates power oscillations at EPs in non-Hermitian lattices.

Findings

Demonstrated diffraction-free beam propagation using EPs in synthetic gauge lattices.

Achieved robust, tunable OAM beam propagation in discrete photonic lattices.

Observed power oscillations at the EP of a non-Hermitian lattice.

Abstract

We propose to use exceptional points (EPs) to construct diffraction-free beam propagation and localized power oscillation in lattices. Specifically, here we propose two systems to utilize EPs for diffraction-free beam propagation, one in synthetic gauge lattices and the other one, in unidirectionally coupled resonators where each resonator individually is capable of creating orbital angular momentum beams (OAM). In the second system, we introduce the concept of robust and tunable OAM beam propagation in discrete lattices. We show that one can create robust OAM beams in an arbitrary number of sites of a photonic lattice. Furthermore, we report power oscillation at the EP of a non-Hermitian lattice. Our study widens the study and application of EPs in different photonic systems including the OAM beams and their associated dynamics in discrete lattices.