High-Resolution Sensing System Based on Fiber Bragg Grating Fabry-Perot Interferometer and Frequency-Domain Demodulation

A high-resolution sensing system is proposed and demonstrated. The sensor head is a Fabry-Perot interferometer formed by two cascaded uniform fiber Bragg grating sensors, and the microwave scanning demodulation system consists of a frequency-stabilized laser, a microwave generator, an electro-optic modulator, a photodetector, and a data acquisition unit. Owing to the ultra-narrow transmission bands of the sensor head and the small resolution of the microwave scanning demodulation system (at the order of kHz), the system can realize a high resolution for strain, curvature, and lateral force sensing, up to n epsilon, 10(-3) m(-1), and mu g, respectively, with sensitivities of -9.696 MHz/mu epsilon, -4346.97 MHz/m(-1), and -120.02 MHz/g, respectively. Because of the fast frequency shifts of the microwave generator, the system proposed in this paper has high potential for dynamic signal sensing.