介质的三阶非线性性质会引起光场的非线性相移,而这类介质中当光强及介质的特性参数满足一定条件时,可以使光场的演化进入混沌的状态.从麦克斯韦方程组出发,推导了基于介质三阶非线性效应的麦克斯韦-布洛赫方程,并将其转化为归一化的洛伦兹方程形式.利用此方程,数值模拟了光场稳态及混沌态的演化过程.研究结果表明,三阶非线性介质中光场的演化可以进入混沌状态,这种状态对于控制材料中如自聚焦等有害的三阶非线性效应是不利的.

The third order nonlinearities in optical materials could induce chaos of the optical field when the material characteristic and laser parameters satisfy some special requirements.In this paper,we start from the Maxwell equations,derive the Maxwell-Bloch equations based on third order nonlinear material,and then transform them into the Lorentz form.Based on these equations,the stable optical field evolution and the chaos are numerically simulated.According to the simulating results,chaos will happen in third order nonlinear material,which leads to unpredictable nonlinear phase shift of the optical field.Such chaos is disadvantageous in suppressing the nonlinear self-focusing in such materials.