LiNbO3晶体中屏蔽光伏孤子自偏转的 时空演化与可控因素

基于带输运模型理论建立了 LiNbO₃ 晶体屏蔽光伏孤子的时空演化动力学方程, 用有限差分方法求解发现, LiNbO₃ 晶体中明、暗屏蔽光伏孤子存在大的自偏转, 并且光孤子形状变得具有不对称性, 偏转方向的曲线斜率绝对值变大, 偏转反方向的曲线斜率绝对值变小. 分析研究表明影响其自偏转度和形变的因素包括受主浓度 N_A, 暗辐射强度 I_d 和外加电场 E₀ . 其他条件不变的情况下N_A 越大, 明孤子的自偏转度与形变越小, 暗孤子的自偏转度与形变反而越大; 对于 I_d , 它对明暗孤子的影响是相同的, I_d 越小, 晶体里诱导出的空间电荷场越容易达到饱和, 当信号光中心光强与暗辐射强度之比为 10^-1时无饱和现象产生; 随着 E₀ 数值的增大, 明孤子的自偏转度和形变减小, 而暗孤子的自偏转度和形变反而增大.

Temporal evolution and controllable factors for self-deflection of screening photovoltaic solitons in LiNbO3 crystal

According to the band transport model theory, we establish the temporal evolution for dynamic equations concerning screening photovoltaic solitons in LiNbO₃ crystal in this paper. By using the finite difference method, we find that there exist large self-deflection bright and dark screening photovoltaic solitons in LiNbO₃ crystal, where the shape of the solitons becomes asymmetry ic with the increase of time. In addition, the absolute value of slope of the curve in deflection direction turns larger, while it tends to be smaller in the opposite direction as time increases. On the other hand, analysis shows that the factors related to the degree of self-deflection and deformation include acceptor concentration N_A, dark radiation I_d and applied electric field E₀. When N_A rises, the self-deflection degree and the deformation of bright soliton become smaller and the counterpart of dark soliton has opposite tendency while I_d and E₀ keep invariant. Moreover, for the bright and dark solitons, the space charge field induced in crystals is easier to reach saturation as I_d diminishes and there is no saturation phenomenon in both cases when the ratio between center light intensity and dark radiation intensity is 10^-1. With the E₀ increases, the bright soliton self-deflection degree and deformation decrease, while the dark soliton self-deflection degree and deformation increase.