High sensitivity high precision MMFBG based on waist-enlarged bitaper for temperature measurement

A high precision multimode fiber grating sensor (MMFBG) is studied. The developed multimode fiber Bragg grating based on waist -enlarged bitaper can excite stable multimode and keep multiple reflection peaks in the reflection spectrum. The virtual peak demodulation method based on MMFBG can reduce the temperature measurement error. When the light is introduced into the sensor, the waist -enlarged bitaper structure will excite high -order modes, and the multimode grating peak signal can be obtained by detecting the reflected signal. The sensing principle of the sensor is theoretically analyzed and simulated, which shows that the proposed sensor can realize high -precision temperature sensing, the temperature sensitivity is 0.012 nm/degree celsius, and the measurement accuracy is optimized from 2.261 % F.S. to 0.876 % F.S. The sensor has the advantages of low cost, high accuracy and easy manufacturing, which has great potential in aero-engine health monitoring, voltage transformer safety control and other fields.