三阶非线性光学中的后弯现象与系统的双稳态

Back Bending Phenomenon of Third Order Nonlinear Optics and Bistable State of the System

直接从介质的非线性极化开始,在牛顿力学框架内,把偶极子的运动方程化为含有立方项的非线性微分方程,并用摄动法进行求解,找到了系统的频率响应曲线、输入信号与输出信号之间的后弯曲线。正是这个后弯现象决定了系统存在两个不同状态,而这两个不同状态正好是系统的双稳态。

In the framework of Newtonian mechanics the motion equation of the dipole is reduced to second-order nonlinear differential equation with cubic term directly from the nonlinear medium polarization, and the equation solved by the perturbation method. The frequency response curve and relationship of the input signal with the output signal are found. It shows that bank bending phenomenon exits in the system. The back bending phenomenon shows that two different states exit in the system, which is an instable state of the system.