晶体电光调制实验中常见“故障”诊断

Fault Diagnosis in the Crystal Electro-Optic Modulation Experiment

为了加深操作者对实验的理解,并通过实验学会对偏振光和非线性光学等知识的应用,从实验的原理入手,揭示了晶体电光调制实验中经常出现的“故障”原因,并提出解决方案。第一,实验中输出信号出现的绝大部分问题,都可以归结为光路没有达到最佳状态。此时可以通过观察干涉圆环图样进行初步判断,再用“两平行一正交”的法则对光路进行调节。第二,输出电压增量ΔV与入射光强I_(0)成正比例变化,和调制信号幅度成反比例变化。据此可以有效地将输出电压的增量控制在合理范围内,保证实验的成效。第三,当起偏器和检偏器平行时,增加偏压后输出电压不增反降。

Several faults in the crystal electro-optic modulation experiment are analyzed and solved to deepen the understanding and application of polarized light and nonlinear optics.Firstly,the problems of output signal can be mostly attributed to the light path which is not turned to optimization.A preliminary judgment should be made by observing the interference pattern,and then the light path can be adjusted by the rule of“two parallel and one orthogonal”.Secondly,the output voltage incrementΔV is proportionate to the intensity of the incident light I_(0),but inversely proportional to the modulation signal amplitude.Accordingly,the increment of the output voltage can be effectively controlled within a reasonable range.Thirdly,when the polarizer and detector are parallel,the output voltage will not increase with the increasing bias voltage but decrease.