基于全光纤Fabry–Perot干涉的差分测振系统设计

在测量过程中，系统光源噪声不可避免，同时光纤对环境较为敏感，这些情况都能引入测量误差。基于上述问题，本文建立了一种基于全光纤F-P干涉的差分测量系统。首先，根据F-P干涉原理的相位方程及2*2单模光纤耦合器在传输过程中直通臂和耦合臂具有90度相位差的特性，推导出结构中两个输出臂的信号相位相反，然后通过让两个信号做差，减少共模噪声的影响，并且所得合成信号幅值是原先信号的2倍，增强了信号的信噪比。实验结果表明，在合作面的振动测量过程中，合成信号的信噪比提高了1.2dB，合成信号的重构误差降低了0.5%。在粗糙表面的振动测量下，合成的差分信号的信噪比提高了1.24dB;重构误差降低了3.3%。实验数据表明该结构能够有效降低噪声对有用信号的影响，提高待测信号重构精度。

An all-fiber F-P Interference Vibration Measurement Differential System

In the measurement process, the noise of the system light source is unavoidable, and the optical fiber is sensitive to the environment, which can introduce measurement error. Based on the above problems, a differential measurement system based on all-fiber F-P interference is proposed in this paper. First of all, according to the principle of F - P interference phase equation and 2*2 single mode fiber coupler in the process of transmission through arm with 90 degree phase difference characteristics and coupling arm, deduce the structure of the two output arm signal phase, and then by putting the two signals do bad, to reduce the influence of common mode noise, and the synthetic signal amplitude is 2 times of original signal, to enhance the SNR of signal. The experimental results show that the signal-to-noise ratio (SNR) of the synthesized signal increases by 1.2dB and the reconstruction error of the synthesized signal decreases by 0.5% during the vibration measurement of the cooperative plane. Under the vibration measurement of rough surface, the SNR of the synthesized differential signal is improved by 1.24dB. The reconstruction error was reduced by 3.3%.Experimental data show that the structure can effectively reduce the influence of noise on useful signals and improve the reconstruction accuracy of the signal to be measured.