Research on the influence of temperature on the sensing function of Faraday effect optical magnetic field sensor

The Faraday effect optical magnetic field sensor has broad application prospects in power systems, and the temperature stability of the sensor has always been the focus of research. Existing researches mostly focus on the influence of temperature on the Verdet constant of the magneto-optical material, but there are other temperature factors that are not taken into account, which limits the improvement of the temperature stability of the sensor. In this paper, the effect of magneto-optical crystal (TGG) temperature on the optical rotation coefficient and static operating point of the sensor's sensing function was studied. It was found that the crystal temperature has a significant effect on the optical rotation coefficient and static operating point in the sensing function. The optical rotation coefficient and static operating point fluctuate periodically with the change of crystal temperature. Through the theoretical analysis of the influence mechanism of temperature, it was found that the interference of multiple reflected light in the magneto-optical crystal has a significant influence on the optical rotation coefficient and static operating point. The mechanism of temperature affecting the sensing function was proposed: temperature affects the phase of reflected light through thermo-optical effect and thermal expansion effect, changes the interference state of reflected light, and then affects the optical rotation coefficient and static operating point. Quantitative calculations were carried out on the influence of temperature using the theoretical model. The calculation results are in good agreement with the experimental data. This article provides a theoretical basis for the optimal design of such sensors.