Gap solitons in parity-time symmetric moir\'e optical lattices

Abstract

Parity-time(PT) symmetric lattices have been widely studied in controlling the flow of waves, and recently moir\'e superlattices, connecting the periodic and non-periodic potentials, are introduced for exploring unconventional physical properties in physics; while the combination of both and nonlinear waves therein remains unclear. Here, we report a theoretical survey of nonlinear wave localizations in PT symmetric moir\'e optical lattices, with the aim of revealing localized gap modes of different types and their stabilization mechanism. We uncover the formation, properties, and dynamics of fundamental and higherorder gap solitons as well as vortical ones with topological charge, all residing in the finite band gaps of the underlying linear-Bloch wave spectrum. The stability regions of the localized gap modes are inspected in two numerical ways: linear-stability analysis and direct perturbed simulations. Our results provide an insightful understanding of solitons physics in combined versatile platforms of PT symmetric systems and moir\'e patterns.