Temperature-insensitive current sensor using two cascaded FBGs

Abstract

ABSTRACTWe demonstrate an intensity-demodulated AC current sensor system that can be self-adaptive to high background temperature perturbations. Self-adaptive current detection is achieved by a magnetic circuit design where a pair of tandem FBGs have differential spectral responses to measured current. As a result, the current can be detected from the optical intensity variations in response to the relative spectral shifts of the two FBGs. The sensor system is insensitive to background temperatures because they lead to identical responses of tandem FBGs. Based on the principle, the sensor system was demonstrated and tested for AC current detection when different temperatures were applied to the sensor.