基于双光栅的马赫-曾德尔干涉仪的初步研制

Mach-Zehnder Interferometers Based on Double Gratings

设计和初步制备了基于双光栅的等臂和不等臂马赫-曾德尔干涉仪,两个衍射光栅分别用作光束分裂器和光束复合器。来自激光器的平行光束透过第一光栅后产生多束衍射光,等臂干涉仪使用两个平面反射镜反射两束对称衍射光至第二光栅的同一位置并产生完全重合的衍射条纹,即每束衍射光包含两个成分。利用光探测器监测任一束重合的衍射光束,该光束两成分之间的相位差随时间的变化就能够被准确测定。而不等臂干涉仪仅使用一个反射镜反射某一束衍射光并使之与零级光束透过第二光栅后产生完全重合的衍射条纹。通过使用一个厚度为50μm的玻璃片来改变相位差,对不等臂干涉仪的干涉效果进行了测试,得到了与理论值相符的实验结果。

Balanced and unbalanced Mach-Zehnder interferometers were developed using two photoresist gratings fabricated on slide glass substrate. One grating served as the beam splitter and the other as the beam recombiner. A laser beam was incident on the first grating to produce multiple diffracted beams. The balanced interferometer used two mirrors to reflect two symmetrical diffracted beams onto the second grating, making the two patterns diffracted by the second grating completely superposed. The phase difference between the two components of one of the superposed beams was measured with a photodetector. For the unbalanced interferometer, only one diffracted beam was reflected upon the second grating, producing a diffraction pattern that completely overlaps with that from the zeroth-order beam. Performance of the unbalanced interferometer was investigated by using a 50 μm-thick glass plate to induce the phase difference.