Higher-order surface solitons in one-dimensional Bessel optical lattices

We demonstrate the existence of higher-order solitons occurring at an interface separating two one-dimensional (1D) Bessel optical lattices with different orders or modulation depths in a defocusing medium. We show that, in contrast to homogeneous waveguides where higher-order solitons are always unstable, the Bessel lattices with an interface support branches of higher-order structures bifurcating from the corresponding linear modes. The profiles of solitons depend remarkably on the lattice parameters and the stability can be enhanced by increasing the lattice depth and selecting higher-order lattices. We also reveal that the interface model with defocusing saturable Kerr nonlinearity can support stable multi-peaked solitons. The uncovered phenomena may open a new way for soliton control and manipulation.     

Surface defect gap solitons in superlattices with self-defocusing nonlinearity

We put forward the existence and stability of defect surface gap solitons at the interface between uniform media and an superlattice with self-defocusing nonlinearity. We reveal that the defect plays the significant role in controlling the region of solitons existing. Various solitons are found to be existed in different gaps for different defects. For positive defects, fundamental solitons can exist stably in the semi-infinite gap, and dipole solitons can exist stably in the first gap but they are unstable in the second gap. For zero or negative defects, fundamental and dipole solitons can exist stably in the first gap and the second gap, respectively.     

Vector soliton fission by reflection at nonlinear interfaces

We address the reflection of vector solitons, comprising several components that exhibit multiple field oscillations, at the interface between two nonlinear media. We reveal that reflection causes fission of the input signal into sets of solitons propagating at different angles. We find that the maximum number of solitons that arises upon fission is given by the number of field oscillations in the highest-order input vector soliton.     

Frequency characteristics of the dark and bright surface solitons at a nonlinear metamaterial interface

We investigate the generation and properties of dark and bright surface waves at the interface of a conventional medium and a metamaterial. It is shown that the stable dark and bright surface solitons can coexist even when the nonlinear Kerr coefficients of the two media are negative, completely different from those at the interface between two conventional media. Most importantly, both the dark and bright surface solitons exist only within a certain range of the effective refractive index of the metamaterial, greatly depending on the frequency of the electromagnetic wave propagating in it. Therefore, the generation conditions for surface solitons, and the properties of the generated surface solitons such as the peak positions and the intensity of the dark and bright surface solitons, can be controlled by adjusting the structure parameters of the metamaterial and/or the frequency of the electromagnetic wave.     

Asymmetrical surface soliton trains

We elucidate the existence, stability and propagation dynamics of multi-spot soliton packets in focusing saturable media. Such solitons are supported by an interface beside which two harmonically photonic lattices with different modulation depths are imprinted. We show that the surface model can support stable higher-order structures in the form of asymmetrical surface soliton trains, which is in sharp contrast to homogeneous media or uniform harmonic lattice modulations where stable asymmetrical multi-peaked solitons do not exist. Surface trains can be viewed as higher-order soliton states bound together by several different lowest order solitons with appropriate relative phases. Their existence as stable objects enriches the concept of compact manipulation of several different solitons as a single entity and offers additional freedom to control the shape of solitons by adjusting the modulation depths beside the interface.     

Surface solitons supported by one-dimensional composite Bessel optical lattices

We address the existence of surface solitons at an interface in a defocusing cubic medium with an imprinted one-dimensional （1D） composite Bessel optical lattice. This setting is composed of two Bessel lattices with different orders and different modulation depths, separated beside both sides of an interface. Stability analysis and numerical propagation simulations prove that solitons supported by the model are dynamically stable in the entire domain of their existence. The order of lattice determines the shape of soliton, and the amplitude of soliton depends on the lattice modulation depth. The experimental realization of the scheme is also proposed. Our results may provide another effective way of controlling the shapes of surface solitons and thus their evolutions by introducing a new freedom degree.     

热非局域非线性高阶界面孤子的多种孤子解

讨论了是光束在(1+1)维的热致非局域介质中的传输, 此介质在中心处被分为两部分, 两部分的线性折射率是不同的. 发现在中心处的界面附近存在多阶稳定的界面孤子. 本文研究的是五阶和六阶界面孤子, 它们都存在三种不同的孤子解. 三种孤子解的波形、束宽、光束重心、存在和稳定区间都是不相同的. 五阶孤子的三种解都存在稳定区间, 并且其中两个解存在共同稳定区域. 然而六阶孤子只有其中一种解存在稳定区间.     

Interface discrete light bullets in waveguide arrays

We analyze spatiotemporal light localization at the interface separating two different periodic photonic lattices. We demonstrate the existence of a novel class of continuous-discrete spatiotemporal solitons propagating along the interface, including hybrid staggered-unstaggered discrete light bullets with tails belonging to spectral gaps of different types.     

Interface localized modes and hybrid lattice solitons in waveguide arrays

We discuss the formation of guided modes localized at the interface separating two different periodic photonic lattices. Employing the effective discrete model, we analyze linear and nonlinear interface modes and also predict the existence of stable interface solitons including the hybrid staggered/unstaggered lattice solitons with the tails belonging to spectral gaps of different types.     

Surface gap solitons

We put forward the existence of surface gap solitons at the interface between uniform media and an optical lattice with defocusing nonlinearity. Such new type of solitons forms when the incident and reflected waves at the interface of the lattice experience Bragg scattering, and feature a combination of the unique properties of both surface waves and gap solitons. We discover that gap surface solitons exist only when the lattice depth exceeds a threshold value, that they can be made completely stable, and that they can form stable bound states.     

Nonlinear shift of spatial solitons at a graded dielectric interface

We investigate total internal reflection of optical spatial solitons at the interface between two regions of nematic liquid crystals with different optical densities. Due to nonlinear molecular reorientation, the solitons experience a penetration depth, hence, a lateral shift that depends on the excitation, with lateral shifts from 0.7 to 1.2 mm as input powers increased from 1.6 to 9.3 mW.     

Bi-directional spatial soliton emission at engineered nonlinear waveguide interfaces

We observed tunable bi-directional emission of spatial solitons at a quadratically nonlinear interface in periodically poled lithium niobate planar waveguides. The interface consists of the boundary between two quasi-phase-matched regions with a different poling period. We show the intensity and phase-mismatch (temperature or wavelength) dependence of the phenomena.     

Two-dimensional stationary nonlinear surface solitons in nonlocal nonlinear media

We address two-dimensional surface solitons occurring at the interface between a semi-infinite linear medium and a semi-infinite nonlocal nonlinear medium. We find that there exist stable single and dipole surface solitons. The properties of the surface solitons can be affected by the degree of nonlocality. Interestingly, only when the degree of nonlocality is greater than a critical value, the surface solitons can exist.     

Trapping and fusion of solitons in a nonuniform toda lattice

In this paper we consider strongly localized solitons leading to high energy events in a Toda lattice with springs of distinct nonlinearity. The trapping and superposition of solitons at a single soft spring embedded in a hard host lattice is investigated numerically. We further show the generation of high energy solitons at an interface between a hard and a soft lattice. The behaviour of a soliton incident on an inhomogeneity is approached analytically. The interaction of solitons in an inhomogeneous Toda lattice is compared to that in a homogeneous one.     

Defect solitons supported by the interface between simple lattices and superlattices

We study surface defect solitons (SDSs) at an interface between superlattices and simple lattices with focusing saturable nonlinearity. The properties of the SDSs formed in such kinds of mixed structures are obviously different from those in single superlattices or single ordinary lattices. Research results show that surface solitons with a zero defect or a positive defect are stable in the semi-infinite gap and cannot exist in the first gap. For the case of a negative defect, the stable region of surface solitons will be narrower in the semi-infinite gap with the increase of the defect depth. Surface gap solitons (SGSs) can stably exist in the first gap for a deeper negative defect depth.     

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.     

Soliton emission in amplifying lattice surfaces

We address surface solitons supported by the interface of optical lattices imprinted in saturable media with surface-localized gain. The nonlinearity saturation puts restrictions on the maximal energy flow carried by surface solitons. As a consequence, the presence of a thin amplifying layer near the surface results in the controllable emission of solitons toward the lattice at angles depending on the amplification rate and lattice depth.     

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.     

Multipole-mode surface solitons

We discover multipole-mode solitons supported by the surface between two distinct periodic lattices imprinted in Kerr-type nonlinear media. Such solitons are possible because the refractive index modulation at both sides of the interface glues together their out-of-phase individual constituents. Remarkably, we find that the new type of solitons may feature highly asymmetric shapes, and yet they are stable over wide domains of their existence, a rare property to be attributed to their surface nature.     

Nonspecular total internal reflection of spatial solitons at the interface between highly birefringent media

We investigate total internal reflection of nonlocal spatial optical solitons at the interface between two differently oriented regions of a highly birefringent nematic liquid crystal. The solitons survive the interaction with an induced index mismatch and undergo nonspecular reflection, with an emerging angle differing appreciably from the incidence angle.