基于布里渊散射的光纤传感特性分析

Sensing properties of optical fibers based on Brillouin scattering

探讨光纤传感中布里渊散射频率与应力的变化关系。在现有的布里渊散射频率理论公式的基础上,讨论线偏振光以不同角度入射到保偏光纤时,布里渊散射频率与应力变化的关系,得出以慢轴、快轴,以及与慢轴的夹角0-90°的任意角度入射时,布里渊频率的变化与应力的变化的理论公式。分析显示当线偏振光以慢轴入射保偏光纤时,初始布里渊频率最小,随着入射角的增加初始频率逐步增大,以快轴入射时,初始频率最大。不论线偏振光的入射角如何变化,布里渊频率变化与应力变化呈线性关系,其斜率随入射角的变化有微小变化。提供了保偏光纤的布里渊散射频率与应变关系的理论基础和实验研究的理论依据。

In Brillouin sensors,strain sensitivity need to be expressed with Brillouin frequency properties of fibers. Based on the study of Brillouin frequency theory,the variation of Brillouin frequency describing the strain sensitivity in optical fibers is reported on the derivation of generalized relationships.In particular,the formulations correspond to polarization maintaining fibers at various polarization angles with respect to the slow axis of the fiber. The scope of research encompasses theory involving both single mode as well as polarization maintaining optical fibers subjected to strain under isothermal conditions.The result of theoretical relationships between strain and Brillouin frequency shifts for different polarization angles are as follows： the original frequency at slow axis is lowest while at fast axis is highest,and it gradually increases with the increase of angles to the slow axis. Whatever the angles,changes in Brillouin frequency with relation to the strain is linear,and the change of slope is small with angle variation. Theoretical basis in the Brillouin frequency properties of polarization maintaining fiber is provided for further experiment study.