Contents I. Introduction
Optical voltage sensors (OVSs) offer significant advantages over their electrical counterparts in many aspects, especially in measuring high electric fields. In electrical voltage sensors, oil or gas that is used for insulation leads to the issue of environmental contamination, and their large volume and weight due to the parts made of copper, ceramic, and iron result in difficulty in installation and maintenance [1], [2]. Moreover, the saturation of magnetic susceptibility of the iron core degrades the sensor life time and limits the linear response range, and the thermal heating caused by the surge current can lead to an accidental explosion of the sensor [3]. In contrast, OVSs are immune to the electromagnetic interference which introduces large signal noise in electrical sensors. In optical sensor, the sensing signal is delivered through the optical fiber without any galvanic connection, so that no insulation is required concerning the electrical breakdown. The optical sensor has much wider dynamic range and frequency bandwidth, which enables the measurement of surge current, and has much smaller volume for facilitating the installation and maintenance [4], [5].
