Observation of linear and nonlinear light localization at the edges of moir\'e lattices

TL;DR

This paper demonstrates the first experimental observation of linear and nonlinear light localization at the edges and corners of moiré lattices, revealing how truncation and nonlinearity influence localization and surface soliton formation.

Contribution

It provides the first experimental evidence of localization phenomena caused by truncation in moiré photonic structures, including the transition from linear modes to nonlinear surface solitons.

Findings

Corner linear modes exhibit distinct localization properties from bulk modes.

Nonlinearity induces a crossover from quasi-localized states to surface solitons.

Experimental demonstration of localization due to moiré lattice truncation.

Abstract

We observe linear and nonlinear light localization at the edges and in the corners of truncated moir\'e lattices created by the superposition of periodic mutually-twisted at Pythagorean angles square sublattices. Experimentally exciting corner linear modes in the fs-laser written moir\'e lattices we find drastic differences in their localization properties in comparison with the bulk excitations. We also address the impact of nonlinearity on the corner and bulk modes and experimentally observe the crossover from linear quasi-localized states to the surface solitons emerging at the higher input powers. Our results constitute the first experimental demonstration of localization phenomena induced by truncation of periodic moir\'e structures in photonic systems.