Analytical investigation of response of birefringent fiber Bragg grating sensors in distributed monitoring system based on optical frequency domain reflectometry

When Fiber Bragg gratings (FBGs) are used as strain sensors, both longitudinal and lateral strain can be applied uniformly or non-uniformly over the length of the FBGs. In order for the demodulation of such FBG signal, this paper investigates the response of birefringent FBGs which are monitored by distributed measurement system based on optical frequency domain reflectometry. A numerical model of the distributed measurement system is built based on piece-wise uniform approach, which considers polarization states of propagating lights. The numerical model simulates analytical response of birefringent FBGs especially when birefringence induces power fluctuations in the distributed spectra, which can be noise or new opportunity for sensitive monitoring of birefringence. Simulation results show the relationships between the power fluctuations and the polarization states of the propagating lights. Consequently, appropriate methods of polarization control for sensitive distributed birefringent FBG monitoring are discussed.     

基于OFDR/WDM的光纤光栅传感网络研究

应用光频域反射复用技术与波分复用技术,解决了光纤光栅传感网络的寻址问题;使用可调谐滤波器,实现了复用信号的解调;具体地分析了光频域反射复用技术的基本原理,从理论上推算了系统的空间分辨率和测量范围,并进行了3×3光栅阵列传感网络的实验研究. 该方案充分利用了光信号的频率和波长信息,在光源功率足够大的前提下,显示出新设计的传感网络具有寻址和解调几百个光栅信号的潜在能力,在大型建筑设施分布式二维或三维应力监测中有很好的应用前景.