Kartashov Yaroslav V
Opt Lett. 2022 Sep 1;47(17):4528-4531. doi: 10.1364/OL.471022.
We predict that photonic moiré lattices produced by two mutually twisted periodic sublattices in a medium with Kerr nonlinearity can support stable three-dimensional (3D) light bullets localized in both space and time. The stability of light bullets and their properties are closely connected with the properties of linear spatial eigenmodes of moiré lattices that undergo localization-delocalization transition (LDT) upon the increase of the depth of one of the sublattices forming the moiré lattice, but only for twist angles corresponding to incommensurate, aperiodic moiré structures. Above the LDT threshold, such incommensurate moiré lattices support stable light bullets without an 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 a certain energy threshold. Moiré lattices below the LDT threshold cannot support stable light bullets for our parameters. Our results illustrate that the periodicity/aperiodicity of the underlying lattice is a crucial factor in determining the stability properties of the nonlinear 3D states.
我们预测，在具有克尔非线性的介质中，由两个相互扭曲的周期性子晶格产生的光子莫尔晶格能够支持在空间和时间上都局域化的稳定三维（3D）光子弹。光子弹的稳定性及其特性与莫尔晶格的线性空间本征模的特性密切相关，当构成莫尔晶格的其中一个子晶格的深度增加时，这些本征模会经历局域化 - 非局域化转变（LDT），但仅适用于对应于非 commensurate（非可公度）、非周期性莫尔结构的扭曲角。在LDT阈值以上，这种非 commensurate（非可公度）莫尔晶格支持无能量阈值的稳定光子弹。相比之下，在毕达哥拉斯扭曲角处出现的 commensurate（可公度）或周期性莫尔晶格，其本征模是离域的布洛赫波，仅在一定能量阈值以上才能支持稳定的光子弹。对于我们的参数，低于LDT阈值的莫尔晶格无法支持稳定的光子弹。我们的结果表明，底层晶格的周期性/非周期性是决定非线性3D态稳定性特性的关键因素。
