光纤光栅与受激布里渊信号的耦合特性

近年来,光纤布拉格光栅传感器与全分布式光纤传感器的融合技术受到了广泛关注,然而光纤布拉格光栅与布里渊信号之间的耦合特性鲜有报道。本文研究了光栅类型、波长、反射率及光纤的光致折射率对受激布里渊信号的影响规律,并探讨了空间分辨率对光纤布拉格光栅定位功能的影响。实验结果表明,在布里渊光时域分析系统中,光纤布拉格光栅处有尖锐的反射峰,而啁啾光栅、长周期光栅及光致折射率变化的光纤处均未出现尖锐的反射峰;光纤布拉格光栅反射率与受激布里渊散射功率谱无关;当光纤布拉格光栅的波长接近1 550 nm时,对受激布里渊频移测量的影响最大;在8 m的长度范围内,光纤布拉格光栅的定位误差约为4 cm,并且与空间分辨率无关。

Coupling characteristics between fiber grating and stimulated Brillouin signal

Recently, the integration technique of fiber Bragg grating (FBG) sensors and distributed optical fiber sensors has attracted extensive attention. However, it is unknown about coupling properties between FBG and Brillouin signal. In this paper, we investigate the effects of optical grating types, wavelength and reflectivity and exposure-induced refractive index of optical fiber on stimulated Brillouin signal. Meanwhile, the influence of spatial resolution on positioning of FBG is discussed. Experimental results show that the sharp reflected peak from FBG occurs in the hybrid system of FBG sensor and Brillouin optical time-domain analysis (BOTDA), while no reflected peak occurs for chirped grating and long period grating, as well as exposure-induced refractive index of optical fibers. FBG reflectivity has no connection with power spectrum of simulated Brillouin scattering. It is also shown that when the wavelength of FBG is close to 1 550 nm, the influence on stimulated Brillouin signal is the largest. A positioning error of approximate 4 cm is obtained among a sensing range of 8 m, which is independent on the spatial resolution.