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

Self-deflection of dark and gray photovoltaic solitons

We use both the numerical method and the perturbation technique to investigate the self-deflection process of a dark photovoltaic spatial soliton in a photovoltaic photorefractive crystal with diffusion effect. It is found that the dark soliton does not propagate along a parabolic trajectory, and it becomes grayer during the propagation in the photorefractive crystal. In the normalized coordinate system(ξ,ζ), the dark soliton deflects to the direction of ξ>0, which is different from that of the bright soliton. Besides, the deflection of dark solitons can be controlled effectively by modulating the ratio of effective Glass coefficient r and the intensity of the signal beam. We also investigated numerically the self-deflection characteristic of gray solitons, which depend on the direction of its initial transverse velocity v. When v>0, gray soliton deflects to the direction of ξ>0 in the coordinate system(ξ,ζ); when v<0, it first deflects to the direction of ξ<0，and then bends to the direction of ξ>0 after propagating for a small distance.