二次谐波产生的非线性相移的解析研究

给出一种分析二阶非线性级联效应的解析方法，对Ⅱ型二次谐波产生的非线性级联效应进行了详细的理论研究和分析。结果表明倍频晶体中正交输入两个振幅不相等的基波分量时，在近相位匹配下二阶非线性级联效应能够产生大的相移。利用本文的解析方法可以对任意二阶非线性相移产生的过程进行优化，从而以最小的需求输入功率来获得特定的相移。还对由非线性相移诱导的且与光强有关的偏振旋转效应和一种基于偏振旋转效应的全光偏振开关进行了分析和讨论。本文的结果对于建立一种基于Ⅱ型倍频晶体中非线性相移诱导偏振旋转效应的新全固化被动锁模飞秒激光装置具有十分重要的意义。

Analytical Study of Nonlinear Phase Shifts Via Second-Harmonic Generation

A comprehensive analytical approach towards cascaded second-order nonlinearities was presented. The nonlinear phase shifts by cascading in type Ⅱ second harmonic generation were investigated anlytically. The results show that type Ⅱ second harmonic generation can lead to large intensity dependent phase shifts for the input beams under a variety of conditions, provided that the orthogonal input components have unequal amplitudes. The analytical results can be used to optimize the process of cascaded second-order nonlinearties to obtain a certain phase shift with minimum power requirements. The effect of intensity dependent polarization rotation induced by the nonlinear phase shifts and a kind of all-optical polarization switching based on this effect were analyzed and discussed. These results are quite appealing for developing a new all-solid passive mode-locking femto-second laser device based on the polarization switching.