基于液晶光阀和光束分析仪的Goos-Hnchen位移的简单测量

Simple measurement of optical Goos-Hnchen shift based on liquid crystal light valve and light beam profiler

Goos-Hnchen(GH)位移只有波长数量级,在实验测量上比较困难。提出了一种基于液晶光阀(LCLV)和光束分析仪(LBP)直接测量GH位移的新方法。研究了LCLV对光偏振态调制的特性,结果发现,当外接电压发生变化时,光的偏振态也随之变化。利用LCLV对光偏振态的调制和LBP记录光斑的重心位置的变化,直接测量出TE和TM两种偏振态入射时棱镜单界面反射光束的GH位移差。这个探测方法简单,不需要复杂的外部处理电路,且实验结果与理论结果很吻合,此方法也可以进一步直接测量二维位移。

Due to the tiny shift in order of optical wavelength for Goos-Hanchen （GH） shift, it is very difficult to measure it directly. A novel approach to directly observe the small optical beam shift was proposed based on the liquid crystal light valve （LCLV） and the light beam profiler （LBP）. Polarization of the beam through the LCLV is investigated. It is shown that polarization of the beam changes when the applied voltage changes. The LCLV is utilized to modulate the polarization state of the beam and LBP is used to register the barrycenter of the beam. The difference between the TM and TE polarized longitudinal Goos-Hanchen shift at the condition of total internal reflection on a prism-air interface was detected. This method doesn＇t need complex external processing circuit, and the experimental result shows good agreement with theoretical calculation. The method is advantageous to measure simultaneously the two-dimensional laser beam shift.