三维自散焦介质中光束聚焦的最佳参量选择

Optimum Parameters for Focusing of Optical Beams in Three-Dimensional Self-Defocusing Nonlinear Media

对三维自散焦介质中由交叉相位调制效应诱导的光束聚焦过程进行了系统研究 ,讨论了抽运光振幅、抽运光信号光初始偏移和抽运光信号光波长比三个参量对信号光聚焦过程的影响。根据自散焦介质中强抽运光诱导弱信号光聚焦满足抽运光与探测光模型 ,对传输方程进行了优化 ,大大减少了数值模拟运算时间。数值方法采用分布傅里叶方法。数值模拟结果表明 :抽运光越强、抽运光信号光波长比越大 ,信号光聚焦程度越大 ;抽运光信号光初始偏移存在一个最佳值 ,使得光束聚焦达到最佳效果。通过参量最佳值的选择 ,可提高光束聚焦的效率。

A discussion is given about the focusing of optical beams due to the cross phase modulation in three dimensional self defocusing nonlinear media. The effect on the focusing of the probe beams for the three initial parameters is discussed: the amplitude of the pump beam, the separation between the pump and the probe beam centers and the wavelength ratio of the pump and the probe beams. The coupled amplitude equations are optimized based on the fact that the probe beam is much less intense than the pump beam, and cut the time of operating the programs much too. Our numerical results show that, the greater the amplitude of the pump beam and the wavelength ratio of the pump to signal beam are the better the probe focuses; the initial separation between the pump and the probe beams has an optimum values. The results can be used to design experiments in order to obtain the best effect of the focusing.