光纤布拉格光栅传感器的一种波长解调方法

A Wavelength Demodulation for Fiber Bragg Grating Sensor

光纤布拉格光栅(FBG)经过中心波长解调,可实现对应变、温度等物理量的高精度传感检测.在光纤光栅传感中,如何检测中心波长的微小移位是传感解调的核心问题.为此,文中介绍了一种基于互相关原理的FBG中心波长解调方法.FBG的初始光谱和被调制后的受扰光谱形状相似,只是中心波长产生了漂移,通过对初始光谱与受扰光谱互相关值的解算,即可解调出中心波长的位移量.将实验结果与自相关法、功率加权法和最小二乘法等波长解调方法进行了对比,结果表明互相关方法可以有效地进行中心波长解调.

By demodulating the central wavelength, fiber Bragg grating （FBG） can be used for high precision detection in strain, temperature and other physical quantities. The key problem of this demodulation method is the detection of the slight shift of the central wavelength. In this paper, a FBG central wavelength demodulation algorithm based on cross-correlation is presented. The perturbed and undisturbed spectra of FBG have the similar form, except a slight shift of the central wavelength. By computing the cross-correlation between the perturbed and undisturbed spectrums, the slight shift of the central wavelength can be obtained. Compared with the auto-correlation algorithm, the weighted wavelength algorithm and the least squares algorithm, the cross-correlation algorithm can demodulate the central wavelength shift effectively in experiments.