无对称中心晶体中直接和级联三倍频效应

Direct and Cascading Third Harmonic Generation in Acentric Nonlinear Optical Crystals

考察了无对称中心晶体中三倍频（ＴＨＧ）实验所得到的三次谐波信号的来源：直接三倍频和级联效应．给出了在实验中区分这两种效应所产生的ＴＨ信号的方法，这有利于利用ＴＨＧ实验来测量晶体的有效三阶非线性系数分量值．

The two sources of third harmonic signal in crystals without an inversion center: direct and cascading third harmonic generation, are discussed. And a method for distinguishing the different TH signals are given for the first time. This technique can help us to measure the components of third order nonlinear optical (NLO) suscepfibility in crystal.