2D Solitons in PT-symmetric photonic lattices

TL;DR

This paper demonstrates the experimental realization of 2D PT-symmetric photonic lattices, revealing nonlinear localized solitons and their unique behaviors, including collapse and self-acceleration, expanding the understanding of PT-symmetry in higher dimensions.

Contribution

It introduces a 2D experimental platform for PT-symmetric optics, observing nonlinear solitons and their novel properties beyond previous 1D limitations.

Findings

Observation of nonlinear localization and soliton formation in 2D PT-symmetric lattices

Identification of a family of solitons similar to conservative counterparts

High-power soliton collapse and self-accelerating field generation

Abstract

Parity-time (PT) symmetry has attracted a lot of attention since the concept of pseudo-Hermitian dynamics of open quantum systems was first demonstrated two decades ago. Contrary to their Hermitian counterparts, non-conservative environments a priori do not show real energy eigenvalues and unitary evolution. However, if PT-symmetry requirements are satisfied, even dissipative systems can exhibit real energy eigenvalues, thus ensuring energy conservation in the temporal average. In optics, PT-symmetry can be readily introduced by incorporating, in a balanced way, regions having optical gain and loss. However, all optical realizations have been restricted so far to a single transverse dimension (1D) such as optical waveguide arrays. In many cases, only losses were modulated relying on a scaling argument being valid for linear systems only. Both restrictions crucially limit potential applications. Here, we present an experimental platform for investigating the interplay of PT-symmetry and nonlinearity in two dimensions (2D) and observe nonlinear localization and soliton formation. Contrary to the typical dissipative solitons, we find a one-parametric family of solitons which exhibit properties similar to its conservative counterpart. In the limit of high optical power, the solitons collapse on a discrete network and give rise to an amplified, self-accelerating field.