Abstract:
Aiming at the problem of low sensitivity of wavelength demodulated fiber-optic accelerographs, a theoretical model of fiber-optic Fabry-Pérot (F-P) wavelength demodulated accelerographs is established. Taking the physical model of the fiber-optic F-P accelerograph as an entry point, combined with the basic principle of the F-P interferometer, the theoretical study of its wave detection principle is carried out, and the effects of the stiffness, mass, cavity length, damping and refractive index of the elastic structural body on the sensitivity are dissected. Meanwhile, the fiber-optic acceleration detector based on F-P interferometry is experimentally constructed, and the effects of the main parameters in the model on the sensitivity and performance are verified. In addition, the quality factor (Figure of Merit) is introduced as an index to quantitatively evaluate the comprehensive performance of the sensor in combination with experimental data, which further verifies the correctness and applicability of the theoretical model. By comparing and analyzing the comprehensive performance of FBG and F-P accelerometer, the resonant frequency of the detector is about 740 Hz, which is relatively flat in the frequency range of 10~310 Hz. The corresponding sensitivity is 6.59~15.21 nm/G, the dynamic range is 81.3dB, and the dynamic resolution is 6.25 μG/ \sqrt\mathrmHz . The sensitivity of the sensor is about two orders of magnitude higher than that of the sensor based on FBG, which provides a new idea for the design of fiber-optic wavelength demodulation type high quality factor F-P accelerometer.