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利用光纤光栅的 1、2阶衍射实现温度 /应变复合传感是近年来光纤光栅传感器研究领域的一个热点 .理想情况下 ,光纤光栅的折射率分布函数是单一频率的余弦函数 ,而实际光纤光栅由于制造工艺的影响产生高阶折射率畸变 .本文着重利用光波导模式耦合理论分析了这种非理想的折射率分布对光纤光栅反射性能的影响 ,得出了 2阶折射率畸变将引起光栅的 2阶衍射的结论 ;并简要探讨了利用光纤光栅的 1、2阶衍射实现温度 /应变复合传感方案存在的可能性
It is a hot topic in the field of FBG sensor to use the first and second order diffraction of fiber grating to realize the temperature / strain composite sensing.In the ideal situation, the FBG’s refractive index distribution function is the cosine function of single frequency, while the actual FBG Due to the influence of the manufacturing process, high-order refractive index distortion is caused.This paper mainly analyzes the influence of this non-ideal refractive index distribution on the optical fiber grating reflection performance by using the optical waveguide mode coupling theory, and concludes that the second-order refractive index distortion will cause the grating 2-order diffraction results are also discussed. The possibility of using the first and second order diffraction of fiber gratings to realize the temperature / strain composite sensing scheme is briefly discussed