To address the need for high electrical insulation, strong immunity to electromagnetic interference, and miniaturized AC electrical-signal detection in complex electromagnetic environments, we propose and experimentally demonstrate a fiber-optic sensor based on a piezoelectric ceramic (PZT)-driven ring tapered-fiber resonator. The applied AC excitation is converted into periodic mechanical deformation through the inverse piezoelectric effect of the PZT, and the resulting strain modulates the resonator response, enabling optical demodulation of the input frequency and amplitude. A comprehensive figure of merit was introduced to optimize the tapered-fiber geometry, yielding an optimal waist diameter of approximately 10 μm. The sensor can effectively distinguish both single- and dual-frequency AC signals. Over the range of 50–500 Hz, the demodulated frequency agrees closely with the input frequency, with a linear fitting coefficient of 0.9999. At a fixed driving frequency of 250 Hz, the amplitude of the characteristic spectral peak increases nearly linearly with the input voltage amplitude, with a fitting coefficient of 0.9945. The device also exhibits good stability over 30–150 °C and during 70 h of continuous operation. With its simple structure, low cost, and strong immunity to electromagnetic interference, this sensor provides a practical solution for AC electrical-signal detection in complex environments.
Zhang et al. (2026) studied this question.