Yuqiang Yang

Sensitivity-enhanced temperature sensor by hybrid cascaded configuration of a Sagnac loop and a F-P cavity

A hybrid cascaded configuration consisting of a fiber Sagnac interferometer (FSI) and a Fabry-Perot interferometer (FPI) was proposed and experimentally demonstrated to enhance the temperature intensity by the Vernier-effect. The FSI, which consists of a certain length of Panda fiber, is for temperature sensing, while the FPI acts as a filter due to its temperature insensitivity. The two interferometers have almost the same free spectral range, with the spectral envelope of the cascaded sensor shifting much more than the single FSI. Experimental results show that the temperature sensitivity is enhanced from −1.4 nm/°C (single FSI) to −29.0 (cascaded configuration). The enhancement factor is 20.7, which is basically consistent with theoretical analysis (19.9).

Temperature-insensitive current sensor using two cascaded FBGs

ABSTRACT We 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.