Surface superlattice solitons in nonlocal nonlinear media

We analyse surface solitons at the interface between a one-dimensional photonic superlattice and a uniform medium with weak nonlocal nonlinearity. We demonstrate that in deep lattices there exist three kinds of surface solitons when the propagation constant exceeds a critical value, including two on-site solitons and one off-site soliton. These three kinds of surface solitons have unique dynamical properties. If the relative depth of the superlattice is low, there is only one kind of off-site soliton; however, the solitons of this kind can propagate stably, unlike their deep superlattice counterparts. Dipole surface solitons are also investigated, and the stable domain is given.     

Gaussian solitons in nonlocal media: variational analysis

Exact solutions of Gaussian solitons in nonlinear media with a Gaussian nonlocal response are obtained. Using the variational approach, we obtain the approximate solutions of such solitons when the degree of the nonlocality is arbitrary. Specifically, we study the conditions for Gaussian solitons that propagate in weakly and highly nonlocal media. We also compare the variational result with the known exact solutions for weakly and highly nonlocal media.     

Propagation properties of spatial optical solitons in different nonlocal nonlinear media with arbitrary degrees of nonlocality

We address the physical features exhibited by spatial optical solitons propagating in nonlocal Kerr-type media with Gaussian-shaped response and exponential-decay response, respectively. An iteration algorithm based on the split-step Fourier method is developed to obtain the numerical solutions of the solitons for the nonlocal nonlinear Schrödinger equation with arbitrary degrees of nonlocality. Our numerical results show that the soliton properties in the normalized system are different with the change of the degree of nonlocality and with the different responses. The profiles undergo a gradual and continuous transition from a Gaussian-shaped function in the strongly nonlocal case to a hyperbolic secant function in the local case for the Gaussian-shaped response, but for the exponential-decay response, the soliton profile is not Gaussian-shaped even in the strongly nonlocal cases. For the same response function, the stronger the nonlocality is, the higher the critical powers for solitons are and the larger of the phase shifts of the solitons. For the same degrees of nonlocality, when the degrees of nonlocality is larger enough, both the critical power and the phase shift for the Gaussian-shaped response are larger than that for the exponential-decay response.     

Dynamics of surface dipole and tripole solitons in nonlocal nonlinear media with optical lattice field

We find the existence conditions for stationary dipole and tripole surface solitons formed at the interface of a nonlocal nonlinear medium and a lattice with linearly modulated frequency. We investigate how the degree of nonlocality, the depth, and the modulation frequency of the optical lattice field affect on the existence of the surface solitons and their dynamics. The relationship between the power and the model parameters is identified. The stability of the surface dipole and tripole solitons is numerically investigated.     

非局域非线性介质中空间暗孤子的理论和实验研究

对非局域非线性介质中的空间暗孤子进行了研究.理论上运用牛顿迭代法求解非局域非线性薛定谔方程,得到了不同传播常数下的非局域空间暗孤子的数值解,发现在任何非局域程度以及任何传播常数条件下,都存在暗孤子的解,而且孤子的束宽与非局域程度存在一定的关系.实验上,在染料溶液中观测到了空间暗孤子在非局域非线性介质中的形成.利用输入功率所引起的非线性效应强度的变化,分析了背景光波形对暗孤子的影响,数值模拟结果与实验结果相符合. 关键词： 非局域非线性 空间暗孤子     

Elliptical Gaussian solitons in synthetic nonlocal nonliear media

This paper studies analytically and numerically the dynamics of two-dimensional elliptical Gaussian solitons in a "double-self-focusing" synthetic nonlocal media featuring elliptical and circular Gaussian response with different degrees of nonlocality.Based on the variational approach,it obtains the approximately analytical solution of such Gaussian elliptical solitons.It also computes the stability of the solitons by numerical simulations.     

强非局域非线性介质中的涡旋光孤子

满足强非局域条件时，光束在非局域非线性介质的传输过程由Snyder-Mitchell模型描述.在旋转柱坐标系下求解了Snyder-Mitchell模型，得到涡旋光孤子的自相似旋转解析解.结果表明，涡旋光孤子解在径向是惠特克函数与幂函数的乘积，光束的光强呈环形分布，光束绕光束中心旋转. 关键词： 非局域非线性介质 强非局域性 涡旋光孤子 惠特克函数     

Variational solutions for Hermite--Gaussian solitons in nonlocal nonlinear media

The physical features exhibited by Hermite--Gaussian (HG) beams propagating in nonlocal nonlinear media with Gaussian-shaped response are discussed with an approximate variational method. Using direct numerical simulations, we find that the beam properties in the normalized system are different with the change of the degree of nonlocality. It is shown that initial HG profiles break up into several individual beams with propagation when the degree of nonlocality $\alpha$ is small. HG beams can propagate stably when $\alpha$ is large enough.     

Interface kink solitons in defocusing saturable nonlinear media

We report on the dynamics of semi-localized nonlinear optical modes supported by an interface separating a uniform defocusing saturable medium and an imprinted semi-infinite photonic lattice. Out-of-phase and in-phase kink solitons composed by dark-soliton-like pedestals and oscillatory tails are found. Two branches of out-of-phase kink solitons exist in shallow lattices. Saturable nonlinearity enhances the pedestal height and renormalized energy flow of kink solitons evidently. While in-phase kink solitons are always unstable, out-of-phase kink solitons will be completely stable provided that lattice depth exceeds a critical value. Furthermore, stable kink solitons in the higher band gaps are also possible. Our results may give a helpful hint for understanding the dynamics of kink solitons with high pedestals in other fields.     

强非局域非线性介质中拉盖尔-高斯型光孤子相互作用

利用强非局域非线性介质中傍轴光束传输的线性模型(修正的Snyder-Mitchell模型)讨论了两束共线(即光束中心和传输方向都相同)拉盖尔-高斯型光孤子的传输过程. 改变双光束的相对阶数和相对强度比,叠加光场在传输截面上的光强分布呈现出多样性,通过叠加的方法在该介质中产生了多环形光孤子. 一定条件下传输光束在传输过程中会出现旋转现象,叠加光场成为旋转光场,给出了旋转光束的旋转条件以及旋转速度. 进一步利用拉盖尔-高斯光束在传输过程中特有的螺旋相位特点分析了光场截面强度多样性产生的物理机理. 关键词： 强非局域非线性介质 拉盖尔-高斯型光孤子 共线传输 涡旋相位     

Dipole solitons in an optical lattice with longitudinal modulation

In this paper, we numerically demonstrate the (1+1)-dimensional dipole solitons can exist in a new Kerr-type optical lattice with longitudinal modulation that fades away and boosts up alternately. The solitons whose two dipoles simultaneously located at one lattice site and at two adjacent lattice sites are investigated, respectively. The results show that, in the two cases, the dipole solitons can be stably trapped in this kind of lattice by properly adjusting lattice parameters and soliton parameters when the repulsive force of dipoles balances the centripetal force resulting from the lattice potential effect on dipole solitons. In addition, the trapping of dipole solitons with an incident angle or the initial center position is discussed.     

Spinning solitons in cubic-quintic nonlinear media

We review recent theoretical results concerning the existence, stability and unique features of families of bright vortex solitons (doughnuts, or ‘spinning’ solitons) in both conservative and dissipative cubic-quintic nonlinear media.     

强非局域非线性介质中的二维库墨-高斯孤子簇

利用自相似技术求解一个在强非局域非线性条件下的(2+1)维非线性薛定谔方程,得到一个精确的库墨-高斯解析解,数值模拟与解析解的一致性表明,这种库墨-高斯孤子形成了一类空间孤子簇.发现这种非局域孤子具有较大的相移.     

Stable high-dimensional solitons in nonlocal competing cubic-quintic nonlinear media

We find and stabilize high-dimensional dipole and quadrupole solitons in nonlocal competing cubic-quintic nonlinear media. By adjusting the propagation constant, cubic, and quintic nonlinear coefficients, the stable intervals for dipole and quadrupole solitons that are parallel to the x-axis and those after rotating 45° counterclockwise around the origin of coordinate are found. For the dipole solitons and those after rotation, their stability is controlled by the propagation constant, the coefficients of cubic and quintic nonlinearity. The stability of quadrupole solitons is controlled by the propagation constant and the coefficient of cubic nonlinearity, rather than the coefficient of quintic nonlinearity, though there is a small effect of the quintic nonlinear coefficient on the stability. Our proposal may provide a way to generate and stabilize some novel high-dimensional nonlinear modes in a nonlocal system.     

Spatial optical solitons in fifth order and seventh order weakly nonlocal nonlinear media

We analytically study the (1 + 1)-dimensional spatial optical solitons in weakly nonlocal nonlinear media with cubic–quintic nonlinearity (fifth order nonlinear media) and cubic–quintic–septic nonlinearity (seventh order nonlinear media). Explicit solutions are derived, which include optical bright solitons, singular solutions and singular triangular periodic solution.     

Two-dimensional spatial solitons in highly nonlocal nonlinear media

We investigate, analytically and numerically, a class of novel higher-order spatial solitons in two transverse-dimensions, in highly nonlocal nonlinear media. The stability of these solutions in propagation is confirmed by direct numerical simulation. Our results demonstrate that the higher-order spatial solitons in highly nonlocal nonlinear media can exist in various forms, such as the fundamental solitons, vortex-ring solitons, multipole solitons, and fractional solitons.     

Multipole surface solitons supported by the interface between linear media and nonlocal nonlinear media

We address multipole surface solitons occurring at the interface between a linear medium and a nonlocal nonlinear medium. We show the impact of nonlocality, the propagation constant, and the linear index difference of two media on the properties of the surface solitons. We find that there exist a threshold value of the degree of the nonlocality at the same linear index difference of two media, only when the degree of the nonlocality goes beyond the value, the multipole surface solitons can be stable.     

Elliptic incoherent accessible solitons in strongly nonlocal media

We study the propagation of elliptic incoherent accessible solitons in strongly nonlocal media with noninstantaneous Kerr nonlinearity. For this soliton to exist, the coherence properties of the incoherent beam should be anisotropic. The total power of the incident beam should also equal to a critical value which depend on the beam width as well as the coherence properties. When initial parameters of the beam do not satisfy the existence conditions, the elliptic incoherent accessible solitons will undergo linear harmonic oscillation in different states. Corresponding properties are studied in detail.     

Periodic solitons in nonlocal nonlinear media

We identify periodic solitons in nonlocal nonlinear media: multi-hump soliton solutions propagating in a fully periodic fashion. We also demonstrate recurrences and breathers whose evolution is statistically periodic and discuss why some systems support periodic solitons while others do not.     

Optical solitons supported by finite waveguide lattices with diffusive nonlocal nonlinearity

We investigate the properties of fundamental, multi-peak, and multi-peaked twisted solitons in three types of finite waveguide lattices imprinted in photorefractive media with asymmetrical diffusion nonlinearity. Two opposite soliton self-bending signals are considered for different families of solitons. Power thresholdless fundamental and multi-peaked solitons are stable in the low power region. The existence domain of two-peaked twisted solitons can be changed by the soliton self-bending signals. When solitons tend to self-bend toward the waveguide lattice, stable two-peaked twisted solitons can be found in a larger region in the middle of their existence region. Three-peaked twisted solitons are stable in the lower (upper) cutoff region for a shallow (deep) lattice depth. Our results provide an effective guidance for revealing the soliton characteristics supported by a finite waveguide lattice with diffusive nonlocal nonlinearity.