Inherent temperature compensation of a dual-mode fiber voltage sensor with coherence-tuned interrogation

We investigate the effects of temperature on a optical fiber voltage sensor. The sensor is based on the converse piezoelectric effect of quartz. The piezoelectric deformation of the cylinder-shaped transducer crystal induced by an applied at voltage is sensed by an elliptical-core dual-mode fiber. The resulting modulation of the differential phase of the LP₀₁ and even LP₁₁ modes of the fiber is remotely detected by coherence-tuned interrogation using a 780-nm multimode laser diode source. A second dual-mode fiber acts as a receiver interferometer. We determine the influence of temperature on the scale factor of the transducer and on the accuracy of the interferometric interrogation. We further show that the sensitivity to temperature of the group index difference of the sensor fiber modes can be exploited to temperature-correct the scale factor of the transducer