强非局域空间光孤子在铅玻璃材料中的传输特性

本文研究了矩形和圆形截面铅玻璃介质中强非局域空间光孤子的传输特性.基于镜像法,光束在铅玻璃中的传输被分成独立的两个过程,即孤子的形成和孤子的整体偏转.孤子的形成不依赖于边界,它来源于入射源光束本身形成的折射率分布的作用,所以形成孤子的临界功率只与材料的性质和入射光束束宽有关.孤子的整体偏转在本质上来源于边界的作用,其偏转力在数值上等同于所有镜像光束与源光束之间的作用力.截面圆形和截面矩形的边界分别"镜像"出一个和无穷多个镜像光束,进而导致不同边界条件下孤子不同的偏转轨迹.文中解析求得的孤子的临界功率以及两 关键词： 空间光孤子 强非局域 镜像法 铅玻璃     

有界非局域非线性介质中空间光孤子传输的研究

对有界非局域非线性介质边界对孤子传输的影响进行了研究.基于非局域非线性薛定谔方程以及热传导的泊松方程,采用格林函数法求出了强非局域介质铅玻璃的响应函数和临界功率;从光线方程出发得到了偏离材料中心入射的光束中心振荡轨迹以及周期的解析解.通过数值模拟证明了该结果在不靠近样品边界的范围内都是准确的. 关键词： 空间光孤子 铅玻璃 非局域非线性     

基于强非局域空间光孤子的温度传感器原理

为了让温度传感器在集成化全光控制中找到实现途径,提出一种基于非局域空间光孤子传输的温度传感器的理论方案.以铅玻璃作为非局域空间光孤子的传输介质,通过研究圆柱形铅玻璃中,中心入射光束在传输过程中的相移问题,得出在环境温度0.32℃的改变就可以引起孤子π相移的结论.此温度改变对相移的调制有望为基于干涉仪原理的温度传感器提供...     

基于强非局域空间光孤子的温度传感器原理

为了让温度传感器在集成化全光控制中找到实现途径,提出一种基于非局域空间光孤子传输的温度传感器的理论方案.以铅玻璃作为非局域空间光孤子的传输介质,通过研究圆柱形铅玻璃中, 中心入射光束在传输过程中的相移问题, 得出在环境温度0.32 ℃的改变就可以引起孤子π相移的结论.此温度改变对相移的调制有望为基于干涉仪原理的温度传感器提供一个可行且灵敏度较高的实现方案.     

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。     

强非局域空间光孤子大相移的理论研究以及应用方案设计

本文发展了郭旗等人的唯像理论,发现在铅玻璃中,孤子随着本身功率或者抽运光孤子功率几十个毫瓦的变化,就会出现π的附加相移.基于抽运光孤子功率对弱信号光孤子相位有着高调制灵敏度的结论,提出了一种较可行的光开关实现方案. 关键词： 强非局域 空间光孤子 大相移     

光伏暗孤子和灰孤子的自偏转

分别用数值法和微扰法研究了考虑背景光时光伏暗空间孤子的自偏转特性.与亮孤子不同，暗孤子光束中心的运动轨迹不为抛物线.在归一化的直角坐标系(ξ,ζ)中，暗孤子朝ξ>0的方向偏转；同时，暗孤子光束中心光强发生改变.通过调节晶体对信号光和背景光的有效光伏系数之比r或信号光光强可以控制它的自偏转.还用数值方法研究了灰空间孤子的自偏转特性，发现灰孤子光束自偏转特性依赖于横向初速度v.当v>0时，灰孤子光束朝ξ>0的方向 关键词： 光伏空间暗孤子 光伏空间灰孤子 扩散效应 自偏转     

闭路光伏暗空间孤子的自偏转特性研究

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。     

非相干耦合的亮和暗光伏空间孤子对的偏转特性

采用数值方法研究了在一个具有扩散效应的光伏光折变晶体中的非相干耦合的亮和暗光伏空间孤子对的偏转特性.结果表明,由于非相干相互作用,晶体中的一个亮孤子和一个暗孤子互相俘获,且两个孤子的中心沿着相同的轨迹移动.发现,当亮孤子的入射峰值强度不变时,通过调节暗孤子的入射背景强度可以控制亮孤子的偏转;当暗孤子的入射背景强度处于一个特殊值时,亮孤子的偏转被抑制,而当暗孤子的入射背景强度偏离这个特殊值时,亮孤子发生偏转.同样,当暗孤子的入射背景强度不变时,其偏转可以通过调节亮孤子的入射峰值强度来控制.     

光折变明孤子的自偏转演化特性

利用一维稳态光折变空间光孤子的统一理论，研究了负载电阻对屏蔽、光伏和屏蔽光伏明孤子自偏转特性的影响。结果表明，无论加载电阻与否，这三种类型的光折变明孤子具有类似的自偏转特性，即孤子波沿一个抛物线轨迹运动。调节负载电阻可以改变孤子的偏转幅度，其中屏蔽光伏明孤子的可调范围最大。     

From electrostatics to optics: The study on the soliton propagation in lead glass using the image beams method

We investigate the soliton propagation in lead glass with rectangle boundary by the method of image beams. This method is the analogue of the electric image method which is used to solve the Poisson type equation. In the general case that the beam width is much smaller than the boundary size, the soliton formation and the soliton steering are analytically studied independently. The critical power of the soliton formation is boundary independent. The boundary effect only provides, for the soliton steering, the dynamic force which is equivalent to the force between the soliton beam and the infinite number of image beams. The closed-form steering trajectories of the solitons are in good agreement with the experimental results.     

Boundary force effects exerted on solitons in highly nonlinear media

We study the effects caused by remote boundaries on soliton dynamics in nonlinear media with a large range of nonlocality, and demonstrate theoretically and experimentally how asymmetric boundary forces can lead to soliton steering and oscillation in predetermined trajectories.     

Large phase shift of spatial solitons in lead glass

A large phase shift of the strongly nonlocal spatial optical soliton (SNSOS) was predicted by Guo et al. [Phys. Rev. E69, 016602 (2004)]. We investigate the phase shift of the SNSOS in lead glass. It is found that the phase shift rate along the propagating direction of such a soliton is one order larger than that of the local soliton. The theory agrees quantitatively with the experiment on the dependence of the phase shift on the degree of nonlocality. We realize a π-phase shift by changing the optical power by about 10?mW around the critical soliton power, which agrees qualitatively with our theoretical result.     

Steering of weak-light spatial solitons in a resonant lambda-type atomic system

We study steering of weak-light solitons in a resonant lambda-type atomic system. Signal soliton steering can be realized via input angle and power control of the control soliton. It is shown that, the deflection angle of a vertical input signal soliton increases linearly with the increase of the input angle of the control soliton due to the repulsive effect in collision, and thus leads to the increase of the output position shift of the signal soliton. When a signal soliton is input parallel with a control soliton, the output position shift of the signal soliton depends parabolically on the normalized power of the control soliton. Decreasing their soliton separation can increase the output position shift of the signal soliton. These properties may be useful in all-optical soliton switching and optical information processing, etc.     

Quasi-two-dimensional dark spatial solitons and generation of mixed phase dislocations

This paper presents experimental evidence that orthogonally crossed dark soliton stripes form quasi-two-dimensional spatial solitons with a soliton constant equal to that of singly charged optical vortices. Besides the pairs of oppositely charged optical vortex solitons, the snake instability of the dark formation at moderate saturation is found to lead to generation of steering mixed edge–screw phase dislocations with zero total topological charges. Received: 26 October 1998 / Revised version: 19 January 1999 / Published online: 12 May 1999     

Soliton control in fading optical lattices

We predict new phenomena, such as soliton steering and soliton fission, in optical lattices that fade away exponentially along the propagation direction. Such lattices, featuring tunable decay rates, arise in photorefractive crystals in the wavelength range 360-400 nm. We show that the predicted phenomena offer different opportunities for soliton control.     

Numerical simulation of propagation of a femtosecond optical soliton in a single-mode fiber with allowance for the imaginary part of Raman response

We consider the effect of Raman inertial response of a medium on the stability of a first-order femtosecond soliton. Numerical solution to the high-order nonlinear Schrödinger equation, with the complex Raman term, describing propagation of a femtosecond optical soliton in a single-mode fiber, is obtained. It is shown that a soliton solution of the high-order nonlinear Schrödinger equation exists under certain conditions imposed on the equation coefficients. These conditions lead to limitations on the wavelength, fiber type, and the highest energy. Results of numerical solutions are in agreement with available experimental data.     

各向异性介质中的椭圆空间光孤子特性

对矩形铅玻璃中椭圆孤子的形成进行了理论研究,在理论模型中引入各向异性衍射效应.采用变分法,得到了强非局域线性各向异性椭圆孤子的变分解.结果表明,各向异性衍射效应对椭圆孤子的形成有很大的影响.为了验证变分解的正确性,采用牛顿迭代法算出强非局域线性各向异性椭圆孤子的数值解,变分解和数值解符合得很好.