改进的光纤布喇格光栅应变传感器理论模型

采用微扰法,从FBG受到应力产生应变以后模式场变化的角度,探讨了传输常数和有效折射率的变化,同时对FBG的应变灵敏度系数得出了更精确的结果.研究发现,在1 520 nm到1 610nm波长范围内,轴向应变灵敏度系数介于0.784 4到0.784 6之间,横向应变灵敏度系数介于0.706 5到0.706 7之间,波长漂移跟应变大小有很好的线性关系,波导效应引起的波长漂移是应变的二阶小量,数值很小,对于FBG受轴向应力的情形可以忽略.FBG中心波长漂移的应变灵敏度系数跟布喇格波长的应变灵敏度系数近似相等.

Improved Theoretical Model of Fiber Bragg Grating Strain Transducer

In this paper, perturbation method is introduced to discuss the variety of the propagation constant and the effective index in detail according to the change of the mode field of the FBG under strain, which gives a more accurate result of the strain sensitivity coefficients. The results show that in the wavelength range of 1 520 nm to 1 610 nm, the longitudinal strain sensitivity is between 0. 784 4 and 0. 784 6, and the transverse longitudinal strain sensitivity is between 0. 706 5 and 0. 706 7. The wavelength movement is perfectly in proportion to the strain and the wavelength movement from waveguide effect is the second power of strain. Its value is minute and can be defaulted when FBG is in longitudinal strain field. It is also found that the movement of center wavelength of FBG is approximately equal to the movement of resonance wavelength of FBG.