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1.
Self-Deflection of Dark Screening Spatial Solitons Based on Higher-Order Space Charge Field 下载免费PDF全文
The effects of higher-order space charge field on the self-deflection of dark screening spatial solitons in biased photorefractive crystals are numerically investigated under steady-state conditions. The expression for an induced space-charge electric field including higher-order space-charge field terms is obtained. Numerical results indicate that dark solitons possess a self-deflection process during propagation, and the solitons always bend in the direction of the c axis of the crystal. The self-deflection of dark solitons can experience considerable increase especially in the regime of high bias field strengths. 相似文献
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This paper predicts that bright-dark self-coupled vector solitons are possible in biased two-photon photovoltaic photorefractive crystals under steady-state conditions. The solutions of these vector solitons can be determined by use of simple numerical integration procedures. When the photovoltaic effect is neglectable, these vector solitons are bright-dark vector screening solitons. When the external bias field is absent, these vector solitons degenerate the bright-dark vector photovoltaic solitons. 相似文献
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The conditions necessary for obtaining holographic solitons in centrosymmetric photorefractive crystals are discussed. When both the intensity modulation of the two interacting waves and the angle between the vector of each beam and the longitudinal axis are small, centrosymmetric photorefractive crystals with a positive (or negative ) effective quadratic electro-optic coefficient are able to support bright (or dark) holographic solitons. The intensity width at half maximum of bright and dark solitons is inversely proportional to the external bias field. The holographic solitons can also exit in dissipative centrosymmetric photorefractive crystals when the applied external bias field is large enough. 相似文献
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Higher-order space-charge field effects on the self-deflection of photovoltaic dark spatial solitons
We investigate theoretically the effects of higher-order space-charge field on the self-deflection of photovoltaic dark spatial solitons by numerical method under steady-state conditions. The expression for an induced space-charge electric field, including higher-order space-charge field terms is obtained. Numerical results indicate that photovoltaic dark solitons possess self-deflection process during propagation, and the solitons always bend in the direction of the c-axis of the crystal. The self-deflection of dark solitons can experience considerable increase especially in the regime of high photovoltaic field strengths. Relevant examples are provided. 相似文献
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The dynamical evolution and stability of
bright dissipative holographic solitons in biased photorefractive materials
in which the self-trapping beam obtains a gain from the pump beam via two-wave
mixing has been investigated numerically. Results show that these solitons are stable relative to small
perturbations. Adjusting some system parameters, such as the bias field and
the angle between beams, can easily control the generation of such solitons.
Potential applications in optical switches or repeaters are discussed. 相似文献
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N. Kirova 《Journal of Physics and Chemistry of Solids》2008,69(9):2248-2251
We consider properties of junctions for the field effect transistors (FET) geometry where molecular crystals or conducting polymers are used as semiconducting layers. In the molecular crystal Coulomb interaction of free electrons with surface polar phonons of the dielectric layer can lead to self-trapping of carriers and to the formation of a strongly coupled long-range surface polaron. The effect is further enhanced in presence of the bias electric field and strongly depends on the gate dielectric used.In conducting polymers instead of the usual band bending near the contact interface, new allowed electronic bands appear inside the band gap. As a result the bias electric field and the injected charge penetrate into the polymer via creation of the soliton lattice whose period changes with the distance from the contact surface. The current through the contact is performed via moving solitons. 相似文献
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Hong T 《Physical review letters》2003,90(18):183901
We show that a weak probe light beam can form spatial solitons in an electromagnetically induced transparency (EIT) medium composed of four-level atoms and a coupling light field. We find that the coupling light beam can induce a highly controllable nonlinear waveguide and exert very strong effects on the dynamical behavior of the solitons. Hence, in the EIT medium, it is not only possible to produce spatial solitons at very low light intensities but also simultaneously control these solitons by using the coupling-light-induced nonlinear waveguide. 相似文献
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闭路光伏暗空间孤子的自偏转特性研究 总被引:3,自引:2,他引:1
通过考虑扩散效应的影响,采用数值方法,研究了一维稳态闭路光伏暗空间孤子的自偏转特性。结果表明,在扩散项的影响下,光伏暗空间孤子光束的中心沿一个抛物线轨迹在光折变晶体光轴方向上产生偏转;孤子中心偏转距离随光伏场以及入射孤子波强度的增加而单调增加。光伏暗空间孤子与明孤子的自偏转规律有明显不同。 相似文献
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证明了在加外电场的光折变晶体中存在非对称全息空间光孤子对,其特征是孤子对中的两个 孤子具有相同的宽度、不同的振幅.给出了这种孤子对的存在曲线,其中存在三个具有不同 特征的区域:对于给定的外加电场来说,当孤子对中两个孤子的入射峰值强度之和与背景光 强度之比足够大或者足够小时,孤子宽度强烈依赖于这个比值,而在此中间的一段区域,孤 子宽度几乎不随这个比值而变化.非对称情况下这个中间区域的范围比对称情况的窄.
关键词:
空间光孤子
光折变非线性光学
全息光栅 相似文献
13.
Nonlinear Dynamics of Wave Fields in Nonresonant Media: From Envelope Solitons toward Video Solitons
We analyze a new class of soliton solutions for a wave field, which describes propagation of soliton-like structures of a circularly polarized electromagnetic field comprising a finite number of field-oscillation periods in a transparent nonresonant medium. The considered solutions feature a smooth transition from the soliton solutions of Schröodinger type, which correspond to long pulses with a large number of field oscillations, to extremely short, virtually single-cycle video pulses. We show that such solutions can also be important for linearly polarized laser fields. The structural stability of few-optical-cycle solitons is demonstrated numerically, including the case of their collision. Based on stability analysis and with allowance for the genealogic relation between the obtained wave solitons and the solitons of the nonlinear Schröodinger equation, we argue that the former solitons can play the same fundamental role in the nonlinear dynamics of the considered wave fields. In particular, it is shown by numerical simulations that the few-optical-cycle solutions turn out to be the basic elementary components of such a dynamical process as the temporal compression of an initially long pulse to a pulse of very short duration. In this case, the minimum duration of a compressed pulse is determined by soliton structures of about minimal duration. 相似文献
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Holographic solitons in photorefractive dissipative systems 总被引:1,自引:0,他引:1
Liu J 《Optics letters》2003,28(22):2237-2239
A new kind of holographic soliton is proposed for a photorefractive dissipative system consisting of a biased photorefractive crystal and a strong pump beam with a uniform spatial distribution in both transverse dimensions. The self-trapping beam in the system can evolve into a spatial soliton when it couples coherently with the pump beam by two-wave mixing. Unlike the holographic solitons recently proposed by Cohen et al. [Opt. Lett. 27, 2031 (2002)], the most unique features of the present solitons are that they have a fixed amplitude and width that are determined completely by the system parameters and that their existence conditions are independent of the polarity of the bias field. Numerical simulations show that these solitons are stable relative to small perturbations. 相似文献
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Zoltán Donkó Peter Hartmann Ranna U. Masheyeva Karlygash N. Dzhumagulova 《等离子体物理论文集》2020,60(8):e201900197
We investigate via molecular dynamics simulations the propagation of solitons in a two-dimensional many-body system characterized by Yukawa interaction potential. The solitons are created in an equilibrated system by the application of electric field pulses. Such pulses generate pairs of solitons, which are characterized by a positive and negative density peak, respectively, and which propagate into opposite directions. At small perturbation, the features propagate with the longitudinal sound speed, from which an increasing deviation is found at higher density perturbations. An external magnetic field is found to block the propagation of the solitons, which can, however, be released upon the termination of the magnetic field and can propagate further into directions that depend on the time of trapping and the magnetic field strength. 相似文献
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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
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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
18.
P. Szankowski M. Trippenbach E. Infeld 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,65(1-2):49-53
We investigate binary soliton collisions in three component BECs with spin exchange interactions and F = 1. For very special values of the coupling constants, these collisions are known to be elastic. We find that, for a further narrow range of parameters, collisions are almost elastic in the sense that a small amount of energy is lost in the process. Emergent solitons are almost identical to the original ones. However, the generic behaviour, found for most values of the two coupling constants, is very different. We observed the creation of spin component oscillations in both emerging entities. We therefore call these entities oscillatons. They are robust and fit an exact solution of the equations. Thus colliding two solitons can in general, somewhat unexpectedly, result in one of two very different outcomes. 相似文献
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A variant of the derivative nonlinear Schrödinger equation for the low frequency circular polarized wave, propagating at a small angle to the bias magnetic field in a ferromagnetic system, is derived by the reductive perturbation expansion method. Bright and dark solitons are obtained. 相似文献
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A theory of the space-charge field is improved in biased photorefractive-phorovoltaic crystals. Steady-state spatial solitons are obtained in the low-amplitude regime in biased photorefractive-photovoltaic crystals. When photovoltaic effect is neglected, these solitons are screening solitons, and their space-charge field is the space-charge field of screening solitons. When the external field is absent, these solitons are photovoltaic solitons for the closed or the open circuit and we also predict that gray solitons exist in photorefractive-photovoltaic crystals, and their space-charge field is the space-charge field of photovoltaic solitons. 相似文献