We study discrete surface solitons in semi-infinite, one-dimensional, nonlinear (Kerr), quasiperiodic waveguide arrays of the Fibonacci and Aubry-André types, and explore different families of localized surface modes, as a function of optical power content (`nonlinearity') and quasiperiodic strength (`disorder'). We find a strong asymmetry in the power content of the mode as a function of the propagation constant, between the cases of focussing and defocussing nonlinearity, in both models. We also examine the dynamical evolution of a completely-localized initial excitation at the array surface. We find that in general, for a given optical power, a smaller quasiperiodic strength is required to effect localization at the surface than in the bulk. Also, for fixed quasiperiodic strength, a smaller optical power is needed to localize the excitation at the edge than inside the bulk.
Nonlinearity-Induced Thouless Pumping in Quasiperiodic Lattices
School of Physical Science and Technology, Lanzhou University（兰州大学物理科学与技术学院）；School of Mathematics and Statistics, Lanzhou University（兰州大学数学与统计学院）；Institute of Fundamental Physics and Quantum Technology, Ningbo University（宁波大学基础物理与量子技术研究所）
We introduce a scheme of a photonic coupler built of two parallel topological-insulator slab waveguides with the intrinsic Kerr nonlinearity, separated by a gap. Josephson oscillations (JO) of a single edge soliton created in one slab, and of a pair of solitons created in two slabs, are considered. The single soliton jumping between the slabs is subject to quick radiative decay. On the other hand, the JO of the copropagating soliton pair may be essentially more robust, as one soliton can absorb dispersive waves emitted by the other. The most robust JO regime is featured by the pair of solitons…
Nonlinearities in lattices with topological band structures can induce topological interfaces in the bulk of structures and give rise to bulk solitons in the topological bandgaps. Here we study a photonic Chern insulator with saturable nonlinearity and show the existence of topological bulk solitons. The fundamental bulk solitons exhibit as semi-vortex solitons, where only one pseudospin component has a nonzero vorticity. The bulk solitons have equal angular momentum at different valleys. This phenomenon is a direct outcome of the topology of the linear host lattice and the angular momentum ca…
We predict the existence and study properties of the valley Hall edge solitons in a composite photonic graphene with a domain wall between two honeycomb lattices with broken inversion symmetry. Inversion symmetry in our system is broken due to detuning introduced into constituent sublattices of the honeycomb structure. We show that nonlinear valley Hall edge states with sufficiently high amplitude bifurcating from the linear valley Hall edge state supported by the domain wall, can split into sets of bright spots due to development of the modulational instability, and that such an instability i…
Trapping and reshaping of low-intensity radiations by soliton trains in gas-filled hollow-core photonic crystal fibers
提出了一种光俘获方案，利用交叉相位调制作用，在填充拉曼惰性气体的空芯光子晶体光纤中，与连续时间脉冲训练串共同传播的超短低幅度辐射被俘获并整形为光孤子串.该方案补充和扩展了最近提出的一种想法，即单脉冲孤子可以在填充惰性气体的对称空芯光子晶体光纤中捕获超短小振幅辐射，从而防止其色散[M. F. Saleh和F. Biancalana，Phys.Rev.A87，043807（2013）]。我们发现一个家庭的三个不同的孤子训练具有不同的传播常数的束缚态，一个是“复制”的捕获脉冲训练。我们分析了自陡化对捕获（即泵浦）和捕获（即探测）场分布的影响，发现自陡化导致泵浦孤子训练的位置均匀移动，但探测器的复杂运动由它们的时间位置和相位的非谐振荡主导。新的捕获方案的目的是光学应用，涉及光场克隆和复制通过波导波过程中，在光子光纤介质中，相互作用时分复用高强度脉冲与连续波辐射共存。
Exceptional points are a ubiquitous concept widely present in driven-dissipative coupled systems described by a non-Hermitian Hamiltonian. It is characterized by the degeneracy of the Hamiltonian's eigenvalues and coalescence of corresponding eigenvectors. Recent developments demonstrated that exceptional points can play an important role in photonics. However, to date, exceptional points have been extensively examined in the systems supporting only a few optical modes, thereby leaving the observation of collective (multimode) effects outside of the scope of study. In the present paper, we ana…
We predict that photonic moiré patterns created by two mutually twisted periodic sublattices in quadratic nonlinear media allow the formation of parametric solitons under conditions that are strongly impacted by the geometry of the pattern. The question addressed here is how the geometry affects the joint trapping of multiple parametrically-coupled waves into a single soliton state. We show that above the localization-delocalization transition the threshold power for soliton excitation is drastically reduced relative to uniform media. Also, the geometry of the moiré pattern shifts the conditio…
