Working principle of Michelson interferometer

The light output from the semiconductor laser is coupled into the optical fiber and divided into two optical fiber arms of the interferometer through the coupler. The reflective film is directly plated on both ends of the optical fiber arm to realize the functions of two mirrors in the traditional Michelson interferometer, and then the reflected light is combined by the coupler to form interference, which is detected by the detector.

The biggest feature of the interferometer is that the optical path is completely closed, and the two arms of the optical fiber can be wound into any shape, with flexible structure, anti-electromagnetic interference, little influence on the measured medium and strong adaptability. Therefore, its application can be extended to many limited fields of traditional interferometers, such as high sensitivity sensing in harsh environment, underwater acoustic detection and underground nuclear explosion verification test. It is an important physical basis for many high-sensitivity optical fiber sensors. Because the light conduction characteristics in the two reflective arms of optical fiber are affected by external conditions such as temperature and pressure, the fiber Michelson interferometer can measure the physical quantities such as fiber strain and temperature.