High-Resolution Fiber Bragg Grating Voltage Sensing System Based on an Optoelectronic Oscillator With the Vernier Effect

A fiber Bragg grating (FBG) voltage sensing system based on an optoelectronic oscillator (OEO) with the Vernier effect is proposed. The system can convert the FBG wavelength shift into the frequency shift of the OEO output microwave signal by introducing dispersion within the loop. Since the wavelength of the FBG varies with voltage by bonding FBG to piezoelectric ceramic (PZT), the system can measure voltage by monitoring the frequency shift of the OEO. Two FBGs are placed inside the loop to form a dual-loop structure. By controlling the length difference between the two loops, the Vernier effect can be realized and the sensitivity of the voltage sensing system is improved. Meanwhile, due to the similar temperature-sensitive performance of the two FBGs, the system can realize temperature compensation to reduce the temperature-induced voltage measurement error. The sensitivity of the voltage sensing system based on the single-loop OEO is 367.25 Hz/V, while the sensitivity of the voltage sensing system based on the dual-loop OEO is 93.07 kHz/V, which is 253 times higher than that of the single-loop voltage sensing system. The temperature sensitivity of the voltage sensing system is measured to be 46.64 kHz/°C. A high-resolution voltage sensing system based on an OEO with the Vernier effect is realized.