Based on the coupled-mode theory and the evanescent field theory
three-layer structure model of the Fiber Bragg Grating(FBG)is proposed and verified through experimental study and reasoning calculation.The sensitivity characteristic of the Bragg wavelength to the refractive index of chemical solution is then obtained.The approximate linear relation between concentration and refractive index is established based on relation theory of concentration and refractive index.The relationships between the concentration and Bragg wavelength of sucrose
ethanol
and Nacl are obtained through analysis.Finally the changes of the Bragg wavelength with the external concentration are obtained by simulations.A chemical concentration sensor is realized with the characteristics of simple structure
small size
good stability
high sensitivity
and free of sensitive components.
关键词
光纤布拉格光栅折射率溶液浓度化学传感器
Keywords
FBGrefractive indexconcentration of solutionchemical sensor