基于FFT-COSS的光纤F-P传感器解调算法

针对光纤Fabry-Perot(F-P)传感器的解调，提出一种基于快速傅里叶变换与余弦相似度(FFT-COSS)的腔长解调算法.首先利用快速傅里叶变换确定腔长的粗测值，然后结合余弦相似度算法求取精确腔长值，作为F-P腔的最终解调结果.仿真结果表明，FFT-COSS算法将解调误差控制在±0.2nm，单次解调的平均时间控制在1s.将该算法应用于石墨烯与聚甲基丙烯酸甲酯(PMMA)混合膜制作的薄膜式F-P传感器微压测试系统.实验结果表明，FFT-COSS算法的拟合度达到0.9908，腔长分辨率优于0.6218nm，单次解调的平均时间控制在1s，与仿真结果相符.

A Demodulation Algorithm for Fiber-Optic F-P Sensor Based on Fast Fourier Transform and Cosine Similarity

Aiming at the demodulation of the Fabry-Perot(F-P)sensor， a cavity length demodulation algorithm based on fast Fourier transform and cosine similarity(FFT-COSS)is proposed. Firstly， the fast Fourier transform is used to determine the rough measurement value of the cavity length， and then the exact cavity length value is obtained in combination with the cosine similarity algorithm as the final demodulation result of the F-P cavity. Simulation results show that the FFT-COSS algorithm controls the demodulation error to ±0.2nm and the average time of a single demodulation to 1s. The algorithm is applied to a thin-diaphragm F-P sensor micro-pressure test system made of a mixed graphene diaphragm and polymethyl methacrylate(PMMA). Experimental results show that the fitted R-squared of the FFT-COSS algorithm reaches 0.9908 and the cavity length resolution is better than 0.6218nm.The average time of a single demodulation is controlled at 1s， which agrees with the simulation results.