Temperature and Vibration Resistant Fiber-Optic Current Sensor With Reflective Recirculating Loop

The stability of the fiber optic current sensor (FOCS) is significantly impacted by the birefringence effects induced by temperature and vibration. This work proposes and experimentally demonstrates a temperature- and vibration-resistant FOCS incorporating a reflective recirculating loop. A transmission model based on the Jones matrix is developed, and the effect of linear and reciprocal circular birefringence in the sensing fiber on FOCS stability is analyzed numerically. The results indicate that the reflective structure effectively improves stability against birefringence induced by environmental disturbances. Experimental results show that the maximum fluctuation of the reflective structure is 0.0066 deg, while the transmissive structure fluctuates by more than 0.94 deg over the temperature range of 25 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula>C to 75 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula>C. Furthermore, the reflective structure demonstrates superior vibration resistance, whereas the output of the transmissive structure is completely drowned out at a vibration amplitude of 10 mm. The reflective structure also exhibits exceptional stability, with a standard deviation (STD) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$6.6 \times 10^{-4}$</tex-math></inline-formula> deg over a period of 1800 s. Therefore, the reflective recirculating loop offers a promising solution for current measurements that are resistant to temperature and vibration, with substantial potential for practical applications in power grids and other precision-demanding environments.