High-Sensitivity Fiber-Optic Voltage Sensor Based on an Optoelectronic Oscillator Using a PZT-Stack and an Equivalent Phase-Shifted Fiber Bragg Grating

A high-sensitivity voltage sensor based on an optoelectronic oscillator (OEO) has been proposed and experimentally demonstrated. An equivalent phase-shifted fiber Bragg grating (EPS-FBG) with a narrow notch in the reflection spectrum, which is bonded on the piezoelectric ceramic multilayer stack (PZT-Stack), is incorporated in the OEO to implement a microwave photonic filter (MPF) and select the single oscillation mode. In the OEO loop, the oscillation frequency is determined by the frequency interval between the optical carrier and the PZT-EPS-FBG notch. Due to the inverse piezoelectric effect of PZT, the variation of the voltage is changed to the wavelength shift of the EPS-FBG and then converted into the frequency shift of the microwave signal using the OEO system based on the wavelength-to-frequency mapping mechanism. Thus, by monitoring the shift of the oscillation frequency of the OEO using an electric spectrum analyzer or a digital signal processor (DSP), high-speed and high-resolution voltage measurements can be realized. The experimental results show that the voltage sensitivity is 0.55 GHz/V. The voltage sensing performance, repetition characteristics, temperature characteristics, hysteresis performance, and stability of the proposed sensor are evaluated experimentally.