Performances of PMMA-Based Optical Fiber Bragg Grating Sensor in Extended Temperature Range

Wei Zhang*, David J. Webb

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


PMMA based optical fiber Bragg grating (POFBG) sensors are investigated in an environmental chamber with controlled temperature and relative humidity at temperature extended to 70 °C. At below a critical temperature of 50 °C the POFBG sensor exhibits good linearity and sensitivity for both temperature and humidity sensing. Nonlinear responses are observed at higher temperature, giving rise to varying, reduced magnitudes of sensitivities. An important feature of POFBG humidity sensing is observed at above critical temperature where the POFBG humidity sensitivity turns from positive to negative. A theoretical model based on Lorentz–Lorenz equation is presented to estimate the dependence of POFBG refractive index on temperature and relative humidity. The experimental results qualitatively agree with the theoretical analyses.
Original languageEnglish
Article number180
Issue number6
Publication statusPublished - 23 May 2021

Bibliographical note

Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


  • fiber Bragg gratings
  • polymer optical fiber
  • thermo-optic effect
  • refractive index humidity dependence


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