Zhang Peng, Wang Ying, Chen Yuru, Lei Xiaohua, Qi Yi, Feng Jianghua, Liu Xianming
Key Lab of Optoelectronic Technology and Systems Ministry of Education, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China.
Sensors (Basel). 2021 Oct 3;21(19):6609. doi: 10.3390/s21196609.
A fast real-time demodulation method based on the coarsely sampled spectrum is proposed for transient signals of fiber optic extrinsic Fabry-Perot interferometers (EFPI) sensors. The feasibility of phase demodulation using a coarse spectrum is theoretically analyzed. Based on the coarse spectrum, fast Fourier transform (FFT) algorithm is used to roughly estimate the cavity length. According to the rough estimation, the maximum likelihood estimation (MLE) algorithm is applied to calculate the cavity length accurately. The dense wavelength division multiplexer (DWDM) is used to split the broadband spectrum into the coarse spectrum, and the high-speed synchronous ADC collects the spectrum. The experimental results show that the system can achieve a real-time dynamic demodulation speed of 50 kHz, a static measurement root mean square error (RMSE) of 0.184 nm, and a maximum absolute and relative error distribution of 15 nm and 0.005% of the measurement cavity length compared with optical spectrum analyzers (OSA).
针对光纤外腔法布里-珀罗干涉仪（EFPI）传感器的瞬态信号，提出了一种基于粗采样光谱的快速实时解调方法。从理论上分析了利用粗光谱进行相位解调的可行性。基于粗光谱，采用快速傅里叶变换（FFT）算法粗略估计腔长。根据粗略估计结果，应用最大似然估计（MLE）算法精确计算腔长。采用密集波分复用器（DWDM）将宽带光谱分解为粗光谱，高速同步ADC采集光谱。实验结果表明，与光谱分析仪（OSA）相比，该系统可实现50kHz的实时动态解调速度、0.184nm的静态测量均方根误差（RMSE），以及测量腔长的最大绝对误差和相对误差分布分别为15nm和0.005%。
