共查询到20条相似文献,搜索用时 31 毫秒
1.
Theoretical results on spatial optical bright solitons excited in arrays of nonlinear defocusing
waveguides, that result from the photovoltaic effect in a photorefractive material, are presented. The existence
of four types of stationary discrete bright staggered solitons, on-site, inter-site, twisted inter-site, and
twisted on-site solitons, is shown both analytically and numerically, and their stability properties are
investigated. The maximum Hamiltonian of staggered solitons with the same total power corresponds to stable modes.
It is shown that for low total power the on-site mode is stable while in the high power regime the inter-site mode
is stable. These results are confirmed numerically. In addition, steering properties of localized modes are
investigated by introducing a transversal translational shift. Because of the translational symmetry between
on-site and inter-site localized modes they are considered as two dynamical realizations of the same moving mode,
and the formalism of the Peierls-Nabarro effective potential is applied to interpret the exchange between trapping
and steering of these modes. This critically depends on the mode’s total power and the introduced phase
difference. On the other hand, steering of twisted inter-site and on-site localized modes is not numerically
observed. Instead, transversal perturbation leads to a transformation of twisted modes either into a trapped
on-site mode of smaller power and radiation, or into two trapped on-site modes. 相似文献
2.
We reveal that lattice interfaces imprinted in nonlocal nonlinear media support surface solitons that do not exist in other similar settings, including interfaces of local and nonlocal uniform materials. We show the impact of nonlocality on the domains of existence and stability of the surface solitons, focusing on new types of dipole solitons residing partially inside the optical lattice. We find that such solitons feature strongly asymmetric shapes and that they are stable in large parts of their existence domain. 相似文献
3.
We demonstrate that an array of discrete waveguides on a slab substrate, both featuring chi2 nonlinearity, supports stable solitons composed of discrete and continuous components. Two classes of fundamental composite soliton are identified: ones consisting of a discrete fundamental-frequency (FF) component in the waveguide array, coupled to a continuous second-harmonic (SH) component in the slab waveguide, and solitons with an inverted FF/SH structure. Twisted bound states of the fundamental solitons are found, too. In contrast with the usual systems, the intersite-centered fundamental solitons and bound states with the twisted continuous components are stable over almost the entire domain of their existence. 相似文献
4.
5.
6.
Garcia-Ripoll JJ Perez-Garcia VM Ostrovskaya EA Kivshar YS 《Physical review letters》2000,85(1):82-85
We find a new type of optical vector soliton that originates from trapping of a dipole mode by the soliton-induced waveguides. These solitons, which appear as a consequence of the vector nature of the two-component system, are more stable than the previously found optical vortex solitons and represent a new type of extremely robust nonlinear vector structure. 相似文献
7.
《Physics letters. A》2020,384(24):126448
We study discrete solitons in zigzag discrete waveguide arrays with different types of linear mixing between nearest-neighbor and next-nearest-neighbor couplings. The waveguide array is constructed from two layers of one-dimensional (1D) waveguide arrays arranged in zigzag form. If we alternately label the number of waveguides between the two layers, the cross-layer couplings (which couple one waveguide in one layer with two adjacent waveguides in the other layer) construct the nearest-neighbor couplings, while the couplings that couple this waveguide with the two nearest-neighbor waveguides in the same layer, i.e., self-layer couplings, contribute the next-nearest-neighbor couplings. Two families of discrete solitons are found when these couplings feature different types of linear mixing. As the total power is increased, a phase transition of the second kind occurs for discrete solitons in one type of setting, which is formed when the nearest-neighbor coupling and next-nearest-neighbor coupling feature positive and negative linear mixing, respectively. The mobilities and collisions of these two families of solitons are discussed systematically throughout the paper, revealing that the width of the soliton plays an important role in its motion. Moreover, the phase transition strongly influences the motions and collisions of the solitons. 相似文献
8.
Keqing Lu Wei Zhao Meizhi Zhang Lei Zhang Yongzhuang Chen Jingjun Xu 《Optics Communications》2008,281(1):49-54
We carry out a theoretical investigation of the properties of waveguides induced by photorefractive one-dimensional steady-state gray spatial solitons (i.e., screening solitons, photovoltaic solitons, and screening-photovoltaic solitons). We demonstrate that waveguides induced by photorefractive steady-state gray spatial solitons are only a single guided mode for both all soliton graynesses and all values of ρ, where ρ is the ratio between the soliton peak intensity and the dark irradiance, and moreover, waveguides induced by gray photovoltaic solitons for closed-circuit condition are also only a single guided mode for all electric current densities. We find that the confined energy near the center of a photorefractive steady-state gray spatial soliton increases with ρ and decreases with an increase in the soliton grayness. We also find that the confined energy near the center of a gray photovoltaic soliton for closed-circuit condition increases with the electric current density. On the other hand, waveguides induced by gray screening-photovoltaic solitons are gray screening soliton-induced waveguides when the bulk photovoltaic effect is neglectable and are gray photovoltaic soliton-induced waveguides when the external bias field is absent. 相似文献
9.
The existence and stability of defect solitons in defective PT potentials with real part of dual-frequency lattices are reported. For positive defects, fundamental solitons are always stable in the semi-infinite gap and nonexistent in the first gap. While for negative defects, in the semi-infinite gap, fundamental solitons are stable in most of their existence region apart from low power region, but all the fundamental solitons are stable in the first gap. Dipole solitions are unstable in the whole semi-infinite gap regardless of defects, but in the first gap they can be stable in the low power region for positive defects. 相似文献
10.
The characteristics of spatial optical solitons in planar waveguides based on electrooptical crystals can differ essentially from the corresponding characteristics for a three-dimensional medium. The main experimental findings relating to the effects of the formation of spatial optical solitons and their interaction in optical waveguides in lithium niobite and strontium – barium niobite crystals at very low light intensities are discussed. 相似文献
11.
Waveguides Induced by Screening-Photovoltaic Solitons in Biased Photorefractive-Photovoltaic Crystals 下载免费PDF全文
We investigate theoretically waveguides induced by screening-photovoltaic solitons in biased photorefractive-photovoltaic crystals. We show that the number of guided modes in a waveguide induced by a bright screening photovoltaic soliton increases monotonically with the increasing intensity ratio of the soliton, which is the ratio between the peak intensity of the soliton and the dark irradiance. On the other hand, waveguides induced by dark screening-photovoltaic solitons are always single mode for all intensity ratios and the confined energy near the centre of a dark screening-photovoltaic soliton increases monotonically with the increasing intensity ratio. When the bulk photovoltaic effect is neglectable, these waveguides are those induced by screening solitons. When the external field is absent, these waveguides predict those induced by photovoltaic solitons. 相似文献
12.
13.
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. 相似文献
14.
Subpicosecond pulse compression in nonlinear photonic crystal waveguides based on the formation of high-order optical solitons 下载免费PDF全文
We investigate by numerical simulation the compression of subpicosecond pulses in two-dimensional nonlinear photonic crystal (PC) waveguides. The compression originates from the generation of high-order optical solitons through the interplay of the huge group-velocity dispersion and the enhanced self-phase modulation in nonlinear PC waveguides.Both the formation of Bragg grating solitons and gap solitons can lead to efficient pulse compression. The compression factors under different excitation power densities and the optimum length for subpicosecond pulse compression have been determined. As a compressor, the total length of the nonlinear PC waveguide is only ten micrometres and therefore can be easily incorporated into PC integrated circuits. 相似文献
15.
M. Stojanovi?A. Maluckov Lj. Had?ievskiB.A. Malomed 《Physica D: Nonlinear Phenomena》2011,240(18):1489-1496
Fundamental solitons pinned to the interface between three semi-infinite one-dimensional nonlinear dynamical chains, coupled at a single site, are investigated. The light propagation in the respective system with the self-attractive on-site cubic nonlinearity, which can be implemented as an array of nonlinear optical waveguides, is modeled by the system of three discrete nonlinear Schrödinger equations. The formation, stability and dynamics of symmetric and asymmetric fundamental solitons centered at the interface are investigated analytically by means of the variational approximation (VA) and in a numerical form. The VA predicts that two asymmetric and two antisymmetric branches exist in the entire parameter space, while four asymmetric modes and the symmetric one can be found below some critical value of the inter-lattice coupling parameter—actually, past the symmetry-breaking bifurcation. At this bifurcation point, the symmetric branch is destabilized and two new asymmetric soliton branches appear, one stable and the other unstable. In this area, the antisymmetric branch changes its character, getting stabilized against oscillatory perturbations. In direct simulations, unstable symmetric modes radiate a part of their power, staying trapped around the interface. Highly unstable asymmetric modes transform into localized breathers traveling from the interface region across the lattice without significant power loss. 相似文献
16.
SBN:Cr晶体中孤子诱导的实时平面光波导及其导光特性分析 总被引:2,自引:1,他引:1
通过数值模拟和实验对SBN:Cr晶体中的(1+1)维亮屏蔽空间孤子及其诱导的实时平面光波导的导光特性进行了研究.采用分步束传播法和Petviashvili迭代法对(1+1)维亮屏蔽空间孤子的特性进行了模拟.通过求解本征方程,对孤子诱导平面波导中存在的导波模式进行了数值求解.采用633 nm的He-Ne激光作为孤子诱导光束,532 nm的半导体泵浦的固体激光作为探测光,在固液同成分的SBN:Cr晶体中进行了实验研究.实验结果和数值模拟的结果符合的很好.而且结果表明SBN:Cr晶体中红光诱导的波导可以作为实时光波导. 相似文献
17.
Szameit A Kartashov YV Dreisow F Heinrich M Pertsch T Nolte S Tünnermann A Vysloukh VA Torner L 《Optics letters》2008,33(10):1132-1134
We report the observation of surface solitons in chirped semi-infinite waveguide arrays whose waveguides exhibit exponentially decreasing refractive indices. We show that the power threshold for surface wave formation decreases with an increase of the array chirp and that for sufficiently large chirp values linear surface modes are supported. 相似文献
18.
We analyze stability and generation of discrete gap solitons in weakly coupled optical waveguides. We demonstrate how both stable and unstable solitons can be observed experimentally in the engineered binary waveguide arrays and also reveal a connection between the gap-soliton instabilities and limitations on the mutual beam focusing in periodic photonic structures. 相似文献
19.
This paper shows that waveguides induced by grey screening-photovoltaic solitons are always single mode for all intensity ratios, which are the ratio between the peak intensity of the soliton and the dark irradiance. It finds that the confined energy near the centre of the grey soliton and the propagation constant of the guided mode increase monotonically with increasing intensity ratio. On the other hand, when the soliton greyness increases, the confined energy near the centre of the grey soliton and the propagation constant of the guided mode reduce monotonically. When the bulk photovoltaic effect is neglected for short circuits, these waveguides become waveguides induced by grey screening solitons. When the external bias field is absent, these waveguides become waveguides induced by grey photovoltaic solitons.[第一段] 相似文献
20.
Surface superlattice gap solitons 总被引:1,自引:0,他引:1
We demonstrate that specific surface superlattice gap solitons can be supported at an interface between a one-dimensional photonic superlattice and a uniform medium with saturable nonlinearity. The solitons are stable in the semi-infinite gap but do not exist in the first gap. With the decrease of the power, the solitons jump from the surface site to the next one, and they may continue the motion into the lattices, which offers potential applications for the routing of optical signals. 相似文献