We predict that photonic moiré 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 moiré lattice that undergo localization-delocalization transition (LDT) upon increase of the depth of one of the sublattices forming moiré lattice, but only for twist angles corresponding to incommensurate, aperiodic moiré structures. Above LDT threshold such incommensurate moiré lattices support stable light bullets without energy threshold. In contrast, commensurate, or periodic, moiré lattices arising at Pythagorean twist angles, whose eigenmodes are delocalized Bloch waves, can support stable light bullets only above certain energy threshold. Moiré 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.
Wide-angle emission in cylindrical moiré lattices enabled by rolling origami
Dalian University of Technology（大连理工大学）；Leibniz Institute for Solid State and Materials Research Dresden（德累斯顿莱布尼茨固体与材料研究所）；Institute of Chemistry, Chinese Academy of Sciences（中国科学院化学研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Harbin Institute of Technology (Shenzhen)（哈尔滨工业大学（深圳））；Zhejiang University（浙江大学）；National University of Singapore（新加坡国立大学）
Two-dimensional Thouless pumping of light in photonic moiré lattices
连续传输和量子化传输是完全不同的。后者是由系统的全局性质而不是局部性质决定的，它表现出独特的拓扑特征，其普遍存在的性质使其在许多科学领域中出现。在这里，我们报告的第一次观察到完全二维的无源泵浦光的体模在一个专门设计的倾斜莫尔晶格印在光折变晶体。由于折射率的纵向绝热和周期性调制，在这样的无约束系统中发生泵浦。这种现象的拓扑性质表现在一个泵浦周期内平均的光束质心的位移的幅度和方向上。\rev{Our experimental results are supported by systematic numerical simulations in the frames of the continuous Schrödinger equation governing propagation of probe light beam in optically-induced photorefractive moiré lattice.}我们的系统提供了一个强大的平台，可调公度和非公度几何拓扑泵浦的探索。
