Light bullets in moiré lattices

Abstract: We predict that photonic moir\'e lattices produced by two mutually twisted periodic sublattices in the medium with Kerr nonlinearity can support stable three-dimensional light bullets localized in both space and time. Stability of light bullets and their properties are tightly connected with the properties of linear spatial eigenmodes of moir\'e lattice that undergo localization-delocalization transition (LDT) upon increase of the depth of one of the sublattices forming moir\'e lattice, but only for twist angles corresponding to incommensurate, aperiodic moir\'e structures. Above LDT threshold such incommensurate moir\'e lattices support stable light bullets without energy threshold. In contrast, commensurate, or periodic, moir\'e lattices arising at Pythagorean twist angles, whose eigenmodes are delocalized Bloch waves, can support stable light bullets only above certain energy threshold. Moir\'e lattices below LDT threshold cannot support stable light bullets for our parameters. Our results illustrate that periodicity/aperiodicity of the underlying lattice is a crucial factor determining stability properties of the nonlinear three-dimensional states.