【摘要】 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.更多还原

【Abstract】 We have deduced a two-level form of beam evolution in photonic lattices of semiconductor photorefractive medium and its classical canonical form of the two-level equation.We analytically calculate the fixed points of the classical canonical aligns,analyze its stability and calculate the critical value of topology changes.According to the classical canonical form of the two-level equation,we make space phase diagram,further analyze the self-trapping of beam propagation in semiconductor photorefractive medium and find two kinds of self-trapping:1) Both the population difference and the relative phase in energy levels oscillate near an equilibrium point in the phase space.2) The population difference in energy levels oscillate near an equilibrium point while the relative phase increases monotonously.From the three aspects of high frequency,low frequency,and intermediate frequency,we investigate how an external periodic field influences the self-trapping and find that the external high frequency periodic field may dramatically modulate the critical points at which the transition to self-trapping occurs.It makes the self-trapping occur with small nonlinear effect when the beam propagates in semiconductor photorefractive medium.更多还原