定义
一种依靠自聚焦测量材料Kerr非线性强度的技术。
Z 扫描测量技术[1，2]通常用于测量Kerr非线性的强度（即非线性指数的大小 n2） 的光学材料。从本质上讲，被研究材料的样品通过激光束的焦点移动，并且光束半径（或轴上强度）作为样品位置的函数在焦点后面的某个点进行测量。这些量受自聚焦效应的影响。如果非线性指数为正，并且样品位于焦点后面（如图1所示），则自聚焦会减少光束发散，从而增加检测器信号。如果将样品移动到焦点的左侧，则焦点将向左移动，焦点后较强的散度会降低检测器信号。根据检测器信号对样品位置的测量依赖性，可以计算出非线性指数的大小。
图 1：设置 z 扫描测量。通过孔径的透射率是作为样品位置的函数来测量的。左侧探测器用于监测入射脉冲能量。
请注意，非线性吸收，例如双光子吸收，也会影响测量信号。然而，这可以通过记录整个发射光束的功率来单独测量。有了这些数据，非线性的测量就可以得到纠正。
参考文献
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