Solitons in composite linear-nonlinear moir\'{e} lattices

TL;DR

This paper investigates two-dimensional gap solitons in moiré lattices formed by linear and nonlinear sublattices, analyzing their types, stability, and dependence on lattice geometry, including quasiperiodic and periodic configurations.

Contribution

It introduces the concept of gap solitons in moiré lattices with linear and nonlinear components, exploring their stability and variety based on lattice geometry and vorticity.

Findings

Identification of stable fundamental, quadrupole, and octupole solitons.

Demonstration of stability segments through linear stability analysis.

Confirmation of stability results via direct numerical simulations.

Abstract

We produce families of two-dimensional gap solitons (GSs) maintained by moir\'{e} lattices (MLs) composed of linear and nonlinear sublattices, with the defocusing sign of the nonlinearity. Depending on the angle between the sublattices, the ML may be quasiperiodic or periodic, composed of mutually incommensurate or commensurate sublattices, respectively (in the latter case, the inter-lattice angle corresponds to Pythagorean triples). The GSs include fundamental, quadrupole, and octupole solitons, as well as quadrupoles and octupoles carrying unitary vorticity. Stability segments of the GS families are identified by means of the linearized equation for small perturbations, and confirmed by direct simulations of perturbed evolution.