有偏压的光伏光折变晶体中的空间灰孤子

修正和完善了有偏压的光伏光折变晶体中空间孤子的非线性波动方程的理论.当光伏效应可忽略时,它转化为屏蔽孤子的非线性波动方程;当外电场为零时,它转化为闭路和开路光伏孤子的非线性波动方程.证明了有偏压的光伏光折变晶体中存在着空间灰孤子.它起源于对外电场的非均匀空间屏蔽和光伏效应.当光伏效应可忽略时,它转化为屏蔽灰孤子;当外电场为零闭路时,它预言了在光伏光折变晶体中存在着光伏灰孤子.     

有偏压的光伏光折变晶体中的空间孤子

证明了有偏压的光伏光折变晶体中存在着明、暗稳态的空间孤子.它源于对外电场的非均匀空间屏蔽和光伏效应.与已报道的稳态光折变空间孤子相比,它具有不同的特性.当外电场为某一特定值时,用改变外电场的极性和旋转光的偏振方向可以实现明孤子与暗孤子的相互转换.当外电场足够强可以忽略光伏效应时,它类似于屏蔽孤子;当不存在外电场时,它类似于开路条件下的光伏孤子. 关键词：     

Bright-dark self-coupled vector spatial solitons in biased two-photon photovoltaic photorefractive crystals

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.     

Steady-State Spatial Solitons in Low-Amplitude Regime in Biased Photorefractive-Photovoltaic Crystals

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.     

有分压电阻和e偏振非相干背景光辐照的光折变晶体中非相干耦合空间孤子对

为了得到光折变晶体中非相干耦合空间孤子对统一理论的结果,基于单光子光折变空间光孤子的基本理论模型,建立了稳态条件下有分压电阻和e偏振非相干均匀背景光辐照的单光子光伏光折变晶体中非相干耦合空间孤子对理论. 研究表明:这种孤子对是由两束偏振方向和波长都相同的互不相干光束耦合形成的, 孤子对两光束都能在晶体中稳定传播;当分压电阻、e偏振背景光、外加电场和光伏场取不同值时, 可获得14种光折变非相干耦合空间孤子对. 本文的结果对完善和充实光折变空间孤子理论体系有重要意义.     

有分压电阻和e偏振非相干背景光辐照的光折变晶体中非相干耦合空间孤子对

为了得到光折变晶体中非相干耦合空间孤子对统一理论的结果,基于单光子光折变空间光孤子的基本理论模型,建立了稳态条件下有分压电阻和e偏振非相干均匀背景光辐照的单光子光伏光折变晶体中非相干耦合空间孤子对理论.研究表明:这种孤子对是由两束偏振方向和波长都相同的互不相干光束耦合形成的,孤子对两光束都能在晶体中稳定传播;当分压电阻、e偏振背景光、外加电场和光伏场取不同值时,可获得14种光折变非相干耦合空间孤子对.本文的结果对完善和充实光折变空间孤子理论体系有重要意义.     

Low-amplitude Screening-photovoltaic Spatial Solitons in Biased Photovoltaic Photorefractive Crystals

The low-amplitude spatial solitons in biased photovoltaic photorefractive crystals are investigated theoretically. The analytical solutions for both the bright and the dark low-amplitude screening-photovoltaic spatial solitons in photorefractive crystals are obtained. The expressions for the width of these solitons are given. The explicit expressions for the spatial deflection and angular deviation of the bright low-amplitude screening-photovoltaic spatial soliton are also presented by taking into account the effect of diffusion.     

有偏压的光伏光折变晶体中屏蔽光伏孤子的自偏转

修正了有偏压的光伏光折变晶体中屏蔽光伏孤子的理论。用微扰法研究了屏蔽光伏孤子的自偏转，得出孤子光呸中心的运动为抛物线，并且空间频率分量随传播距离而线性移动，改变外偏压或旋转光的偏振方向可以控制其自偏转。当光伏效应可忽略时，屏蔽光伏孤子的非线性波动方程就转化为屏蔽孤子的非线性波动方程，它的自偏转就转化为屏蔽孤子的自偏转。当外偏压为零时，屏蔽光伏孤子的非线性波动方程就转化为光伏孤子的非线性波动方程，它的自偏转证明了光伏孤子中也存在着自偏转。     

Low-amplitude Screening-photovoltaic Spatial Solitons in Biased Photovoltaic Photorefractive Crystals

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅｓｐａｔｉａｌｓｏｌｉｔｏｎｓｈａｖｅａｔｔｒａｃｔｅｄｇｒｅａｔａｔｔｅｎｔｉｏｎｉｎｔｈｅｐａｓｔｙｅａｒｓ[1～ 11] .Ｔｈｅｙｈａｖｅｂｅｃｏｍｅｏｎｅｏｆｃｏｎｓｉｄｅｒａｂｌｅｓｕｂｊｅｃｔｓｉｎｐｈｏｔｏｒｅｆｒａｃｔｉｖｅｎｏｎｌｉｎｅａｒｏｐｔｉｃｓ .Ｕｐｏｎｉｌｌｕｍｉｎａｔｉｏｎ ,ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅｍａｔｅｒｉａｌｓｃａｎｓｅｔｕｐｓｐａｃｅ ｃｈａｒｇｅｆｉｅｌｄｉｎｃｒｙｓｔａｌｓ,ｗｈｉｃｈｗｉｌｌｉ…     

加外电场的光伏光折变晶体中的空间孤子波

证明了在加外电场的光伏光折变晶体中存在着明、暗稳态空间孤子波.它源于对外电场的非均匀空间屏蔽和光伏效应.同已报道的稳态光折变空间孤子相比，它具有不同的特性和物理根源.当外电场足够强时，它类似于屏蔽孤子；当外电场为零时，它退化成闭路条件下的光伏孤子. 关键词：     

Temporal behavior of spatial solitons in centrosymmetric photorefractive crystals

We investigate theoretically the time behavior of spatial solitons in biased centrosymmetric photorefractive crystals. A one-dimensional time-dependent wave propagation equation in biased centrosymmetric photorefractive crystals is presented. It is shown that the bright solitons exist in both quasi-steady-state and steady-state regimes for high saturation values. When the intensity ratio is smaller than unity, the bright soliton width decreases monotonically to a minimum value toward steady state. Moreover, the time-dependent nonlinear wave equation exhibits only steady-state screening dark spatial solitons.     

含分压电阻的光折变屏蔽光伏空间灰孤子(英文)

为了研究外加偏压光伏光折变晶体中的空间灰孤子,建立了含分压电阻的光折变屏蔽光伏空间灰孤子的演化方程,给出了灰孤子解.采用数值模拟的方法,求解灰孤子的数值表达式,得到了不同参量取值下的灰孤子包络.数值结果表明:当分压电阻、晶体的外加电场和光伏场取不同值时,可以分别得到有无分压电阻的屏蔽灰孤子;开路的光伏灰孤子,有、无分压电阻的闭路光伏灰孤子;有、无分压电阻的屏蔽光伏灰孤子.     

含分压电阻的光折变屏蔽光伏空间灰孤子

为了研究外加偏压光伏光折变晶体中的空间灰孤子,建立了含分压电阻的光折变屏蔽光伏空间灰孤子的演化方程,给出了灰孤子解.采用数值模拟的方法,求解灰孤子的数值表达式,得到了不同参量取值下的灰孤子包络.数值结果表明：当分压电阻、晶体的外加电场和光伏场取不同值时,可以分别得到有无分压电阻的屏蔽灰孤子|开路的光伏灰孤子,有、无分压电阻的闭路光伏灰孤子|有、无分压电阻的屏蔽光伏灰孤子.     

Self-Deflection of Dark Screening Spatial Solitons Based on Higher-Order Space Charge Field

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.     

有偏压中心对称光折变晶体中的屏蔽孤子

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.     

Higher-order space charge field effects on the evolution of spatial solitons in biased photorefractive crystals

We investigate higher-order space charge field effects on the evolution of bright spatial solitons in biased photorefractive crystals under steady-state conditions. Numerical simulations demonstrate that these optical solitons can experience considerable increase in their self-deflection especially in the regime of very high bias field strengths. This process is further studied using perturbation techniques. Our analysis indicates, that for very high bias fields, the self-bending process is further enhanced by a factor that varies cubically with the applied field. Relevant examples are provided.     

弱光强空间屏蔽光伏明孤子的动态演化特性

在忽略晶体损耗和扩散效应的情况下，讨论了加外电场的光伏光折变晶体中弱光强空间屏蔽光伏明孤子及其演化特性，在弱光强条件下得到了空间屏蔽光伏明孤子的解析解表达式，与运用数值计算的方法所得到的结果十分吻合，该方法解决了以往数值求解动态演化方程时必须先数值求解常数分方程或积分方程的问题，讨论了参量失配情况下空间屏蔽光伏明孤子的动态演化特征。     

Waveguides Induced by Screening-Photovoltaic Solitons in Biased Photorefractive-Photovoltaic Crystals

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.     

Holographic solitons in centrosymmetric photorefractive crystals

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.     

UNIVERSAL THEORY OF STEADY-STATE ONE-DIMENSIONAL PHOTOREFRACTIVE SOLITONS

A universal theory of steady-state one-dimensional photorefractive spatial solitons is developed which applies to the steady-state one-dimensional photorefractive solitons under various realizations, including the screening solitons in a biased photorefractive medium, the photovoltaic solitons in open- and closed-circuit photovoltaic-photorefractive media and the screening-photovoltaic solitons in biased photovoltaic-photorefractive media. Previous theories advanced individually elsewhere for these solitons can be obtained by simplifying the universal theory under the appropriate conditions.