High Sensitivity MZI Based on the Modular Interference With Small Group Velocity Dispersion Difference

In fiber interferometric sensor, the smaller the group velocity dispersion difference between two interference modes, the higher the sensor sensitivity. In this article, simulation analysis results showed that there were high-order modes with approximately equal group velocity dispersion in graded index fiber. Based on this, the ring core fiber was employed to inject light into the graded index multimode fiber to selectively excite two modes with smaller group velocity dispersion difference to interfere, so as to improve the performance of the fiber interferometric sensor. The experimental results indicate that the sensor has the strain sensitivity of 176.4 pm/μϵ and temperature sensitivity of 1174.6 pm/°C, which are superior to other interferometric sensors based on graded index fiber, and at a high level in the overall field of interferometric sensors. The new sensor promotes the research value of the graded index fiber in the field of interferometric sensing and provides a new scheme for the research of the sensitivity enhancement of the interferometric sensor.