Fiber Loop Ring-Down Magnetic Field Sensor Using Frequency-Shifted Interferometry and D-Shaped Fiber Coated With Magnetic Fluid

Abstract

In this letter, we demonstrate a low-cost fiber loop ring-down (FLRD) magnetic field sensor using frequency-shifted interferometry. A D-shaped fiber coated with magnetic fluid was used as the sensor head for enhancing the sensitivity and improving the stability. With this scheme, the magnetic field was sensed in the space domain by measuring the ring-down distance, and its measurement accuracy was improved by introducing a temperature controller. The experimental results showed that a sensitivity of 2.53 × 10−3 (km−1ċG−1) was achieved, and a stability of 0.146% was obtained, which is better than those of the current time-domain FLRD sensors based on evanescent field effect.