基于可调谐激光器的光纤光栅高速解调的时延误差补偿方法

Optical delay error compensation method for FBG high-speed interrogator based on tunable laser

基于可调谐激光器的光纤光栅(fiber Bragg grating, FBG)解调仪用于FBG传感器的远距离、高速测量时,光传输时延会导致显著的波长解调误差。本文设计了一种补偿光传输时延导致的FBG解调误差的方法,可调谐激光器在工作光频率范围内进行高线性度的正向、反向扫描,利用正向、反向扫描过程中的光电探测信号的FBG反射峰差异,对光传输时延导致的波长解调误差进行补偿。试验结果表明,在50 kHz解调频率和100 m连接光纤长度条件下,将光传输时延导致的波长解调误差由2 nm降低到小于10pm。

Optical transmission delay could induce significant wavelength demodulation error to the fiber Bragg grating(FBG) interrogators based on tunable laser, especially when they are applied for remote and high-speed measurement of FBG sensors.A method for compensating the wavelength demodulation error of FBG induced by optical transmission delay is proposed.The optical frequency of tunable laser scans in up and down two directions with high linearity in its spectrum range.The wavelength demodulation error is compensated by the detected FBG reflection peak difference between up and down-scan spectrums.Experimental results show that, the wavelength demodulation error induced by optical transmission delay can be reduced from 2 nm to less than 10 pm after compensation, with measurement frequency of 50 kHz and optical fiber length of 100 m.