共查询到19条相似文献,搜索用时 125 毫秒
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推导了光束在半导体光折变介质的光子晶格中演化的二能级形式, 给出了光束在其中传播时二能级方程的经典正则形式. 解析计算出了经典正则方程的不动点并对其稳定性作了分析, 计算出了拓扑结构变化的临界值. 根据二能级方程的经典正则形式做出了空间相图, 进一步分析了半导体光折变介质中光束传输的自囚禁现象, 发现有两种形式的自囚禁: 1)能级中的布居数差和相对相位都在平衡点附近振动; 2)能级中的布居数差在平衡点附近振动, 而相对相位单调变化. 分别从高频、低频、中频三个方面研究了外加周期调制对自囚禁的影响, 发现在高频调制中发生自囚禁现象的相变参数能够被周期场非常有效的调制, 使得光束在半导体光折变介质中传输时, 在非线性效应影响较小时也能够发生自囚禁.
关键词:
半导体光折变介质
自囚禁
二能级形式
周期调制 相似文献
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用干涉法在自散焦光折变晶体 LiNbO3:Fe中写入光子晶格的动态过程中,发现了双光束干涉条纹一分为二,四光束干涉点阵一分为四的分裂现象. 研究证明:这是干涉条纹空间频率的倍频现象,是入射的干涉光场与写入的光子晶格之间相互作用的结果. 本实验说明利用光折变效应可以容易地实现干涉光场空间频率的倍频和空间高次谐波的产生,并可利用产生的空间谐波感应出二倍频和高倍频的光折变光子晶格.
关键词:
光折变晶体
光子晶格
空间谐波 相似文献
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有偏压中心对称光折变晶体中的屏蔽孤子 总被引:7,自引:6,他引:1
给出了中心对称光折变晶体中屏蔽孤子的高阶空间电荷场.当高阶项可以忽略时,这个电荷场就变为早前在中心对称光折变晶体中研究的屏蔽孤子的空间电荷场.研究了中心对称光折变晶体中屏蔽孤子的高阶非线性波动方程.在适当的条件下,这个非线性波动方程能够展示明暗空间光孤子.这类晶体不同于非中心对称晶体,其非线性折射率的改变来源于二次电光效应,而不是一般的线性电光效应.应用光束传播的方法,对这些孤子的稳定性进行了讨论.表明在小的微扰下这类孤子是稳定的,不会发生分裂. 相似文献
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《中国光学与应用光学文摘》2006,(3)
O437 2006032116有偏压中心对称光折变晶体中的屏蔽孤子=Screeningsolitons in biased centrosymmetric photorefractive media[刊,中]/李金萍(中科院西安光机所瞬态光学技术国家重点实验室.陕西,西安(710068)) ,卢克清…∥光子学报.—2006 ,35(2) .—257-260给出了中心对称光折变晶体中屏蔽孤子的高阶空间电荷场。研究了中心对称光折变晶体中屏蔽孤子的高阶非线性波动方程。在适当的条件下,这个非线性波动方程能够展示明暗空间光孤子。应用光束传播的方法,对这些孤子的稳定性进行了讨论。结果表明在小的微扰下这类孤子是稳定的,不会发生分… 相似文献
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介绍一种新的量子隧穿———非线性朗道-基纳隧穿.这种隧穿一般发生在有相互作用的二能级系统中,比如光晶格中的玻色-爱因斯坦凝聚物和分子磁体.相对于传统的线性朗道-基纳隧穿,非线性朗道-基纳隧穿由排斥相互作用带来的非线性会增强隧穿的概率.特别是当非线性非常强时,系统的绝热性会遭到破坏;一个无穷小的线性驱动都会造成有限的隧穿概率. 相似文献
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魏秀芳 《原子与分子物理学报》2015,32(6)
在加速光晶格中玻色-爱因斯坦凝聚体(BEC),当同时考虑两体和三体相互作用时,其能级结构、隧穿率出现了独特的特性.在一维加速光晶格中的BEC,当两体和三体相互作用参数满足一定条件时,非线性两能级体系的能级结构中出现了圈结构,研究得出了圈的宽度随两体和三体相互作用参数变化的关系,并由此分析圈结构的出现及其大小对BEC隧穿率的影响. 相似文献
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在加速光晶格中玻色-爱因斯坦凝聚体(BEC),当同时考虑两体和三体相互作用时,其能级结构、隧穿率出现了独特的特性.在一维加速光晶格中的BEC,当两体和三体相互作用参数满足一定条件时,非线性两能级体系的能级结构中出现了圈结构,研究得出了圈的宽度随两体和三体相互作用参数变化的关系,并由此分析圈结构的出现及其大小对BEC隧穿率的影响. 相似文献
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光折变介质中空间光孤子自弯曲现象研究 总被引:1,自引:0,他引:1
光折变非线性介质在外加直流电压时会引起介质内部电荷移动,而移动后的电荷又会导致空间电荷的扩散效应,从而产生非局域非线性现象。从理论上研究了具有流动和扩散非局域非线性的光折变晶体中所支持的空间光学孤子的传播行为。应用等效粒子近似方法分析了这类介质中(1 1)维空间光学孤子动力学行为,得出孤子运动"加速度"显式解。孤子的有效"加速度"决定于孤子参量和光折变非局域参量。所得的解析结果可在一定参量范围内直接用来计算孤子的传播轨迹。对孤子在光折变非局域非线性作用下的传播动力学行为做了仿真模拟,数值模拟结果与理论分析结论符合得很好。 相似文献
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A rigorous solution is given in the plane-wave approximation for the boundary problem of light reflection from the interface between an isotropic medium and a photorefractive crystal with drift-diffusion nonlinearity. The possibility of realizing hysteresis reflection or optical bistability in the system under certain conditions is shown. Analytical expressions are obtained that describe the hysteresis behavior of reflectivity as a function of the angle of incidence or the strength of a constant external electric field applied to the crystal. The results of the study are of interest for the development of devices controlling laser radiation. 相似文献
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An optical medium whose nonlinearity can be spatially adjusted is considered to study beam reshaping. The concept is applied to perform adiabatic self-focusing of broad beams. Experimental results are obtained in a photorefractive lithium niobate crystal where the self-focusing nonlinearity is controlled over propagation by a temperature gradient. As a demonstration, gradual self-focusing is shown to transform an incoming beam into an output circular spot 10 times smaller over a 2 cm long crystal submitted to a 30 °C temperature gradient. Once formed, the adiabatic self-focused beam has inscribed a funnel waveguide in the crystal. 相似文献
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Krolikowski W Luther-Davies B McCarthy G Bledowski A 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(2):2010-2014
We study formation and interaction of one-dimensional screening solitons in a photorefractive medium with sublinear dependence of the photoconductivity on light intensity. We find an exact analytical solution to the corresponding nonlinear Schrodinger equation. We show that these solitons are stable in propagation and their interaction is generic for solitons of saturable nonlinearity. In particular, they may fuse or "give birth" to new solitons upon collision. 相似文献
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We theoretically studied photorefractive surface waves supported by polymers with orientationally enhanced photorefractive effect. We find that the orientational enhancement and the dependency of the quantum efficiency of generating mobile holes on the electric field make the diffusion nonlinearity in photorefractive polymers dependent not on only the variation of light intensity but also on external electric field, which is very different from the external electric field independent diffusion nonlinearity in inorganic photorefractive crystals. Consequently the profile, frequency and especially the penetration depth of polymeric photorefractive surface waves strongly depend on external electric field, which makes it more controllable than that in photorefractive inorganic crystals. The stability of polymeric photorefractive surface waves, the effects of birefringence component and electro-optic component of orientationally enhanced photorefractive nonlinearity on the formation of x or y-polarized polymeric photorefractive surface waves are also discussed. 相似文献
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E. S. Demidov N. E. Demidova V. V. Karzanov K. A. Markov V. V. Sdobnyakov 《Physics of the Solid State》2009,51(10):2007-2013
Experimental data obtained in the study of transverse current transport in a number of nanosized grained or similar media,
such as porous silicon layers, anodic silicon oxide layers, and silicon nitride layers prepared by ion implantation of nitrogen
into silicon, have been analyzed within the theory of discrete tunneling. It has been demonstrated that the measurements of
current-voltage characteristics of diode structures with dielectric interlayers and embedded grains make it possible to obtain
useful information on the character and sizes of grains or quantum dots in the nanosized grained medium. Amorphous dielectrics
can be considered a grained medium with nanosized composition fluctuations. The current-voltage characteristics of real structures
are determined by both the current nonlinearity associated with the charge carrier injection and the field nonlinearity caused
by the Coulomb blockade of tunneling. 相似文献
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We consider an integrable Hamiltonian system generated by the resonant normal form in order to study a particular mechanism of tunneling. We isolated near doublets of energy corresponding to rotation tori of the classical dynamics counterpart and the degeneracies breakdown is attributed to rotation-rotation tunneling. 相似文献
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We study self-channeling of light waves in a rotated cut of crystals of the 4mm and the 6mm classes, whose dominant mechanism is photorefractive diffusion nonlinearity. The existence of photorefractive line waves that can be guided along the edge of the crystal is suggested and analyzed. 相似文献