近红外波长扫描激光高精度FBG解调系统

High-precision FBG demodulation system using near-infrared wavelength scanning laser

光纤布拉格光栅(FBG)由于其轻巧、规模小、不受电磁干扰和复用能力的影响等优点,广泛用于监视结构健康、机械运行、航空航天和其他领域。引入可调谐扫描激光(TSL)来研制近红外(NIR)范围内的精确光纤布拉格光栅(FBG)波长解调系统,实现高速度、宽范围、高精度的解调。采用一种光纤法布里-珀罗标准具(FFPE)用作波长标记以提取波长在细分波长扫描范围内实现分段线性解调,解决可调扫描激光器带来的非线性问题。引入了另一种光纤法布里–珀罗标准具,实现解调的高精度校准。提出一种多项式最小二乘曲线拟合算法,进一步提高解调的准确性和稳定性,利用了波长范围为1525~1565 nm的近红外波长扫频激光器,得到了非常优异的结果,解调系统的精度为±0.5 pm,实现了高精度、简易化和小型化。

Fiber Bragg grating(FBG)has been widely used in monitoring structural health,mechanical operation,aerospace field,and other physical parameters due to its advantages of being lightweight,tiny scale,immune to electromagnetic interference and multiplexing capability.Tunable scanning laser(TSL)was introduced to fabricate an accurate FBG wavelength demodulating system in the near infrared range(NIR)to achieve highspeed,wide-range,and high-precision demodulation.One fiber Fabry–Perot etalon(FFPE)was used as a wavelength marker to extract wavelength.The wavelength scanning range was subdivided to implement piecewise linear demodulation,which solves the nonlinear problem brought about by tunable scanning laser.Another fiber Fabry–Perot etalon was introduced to realize high-accuracy calibration of the demodulation.A polynomial least square curve fitting algorithm was proposed to further enhance demodulation accuracy and stability.This work has been utilizing a near-infrared wavelength scanning laser with a wavelength range of 1525-1565 nm.It showed a very promising result whereby the accuracy of the demodulating system exceeds±0.5 pm,which achieves high accuracy,simplification and miniaturization.