Relative humidity sensor based on cascaded long-period gratings with hydrogel coatings and Fourier demodulation

Xiujuan Yu, Paul Childs, Min Zhang, Yanbiao Liao, Jian Ju, Wei Jin

Research output: Journal article publicationJournal articleAcademic researchpeer-review

23 Citations (Scopus)


A Mach-Zehnder interferometer based on cascaded long-period gratings with a hydrogel thin-film coating is developed for monitoring the relative humidity (RH). The visibility of fringes and phase shift of the fringes are measured using Fourier analysis. The sensors show good linearity using the visibility of fringes from 60%RH to 100%RH with the ability to measure below 60% at reduced accuracy using the phase shift. An RH accuracy of 0.4% is achieved.
Original languageEnglish
Article number5291749
Pages (from-to)1828-1830
Number of pages3
JournalIEEE Photonics Technology Letters
Issue number24
Publication statusPublished - 1 Dec 2009


  • Cascaded long-period gratings (LPGs)
  • Hydrogel
  • Optical fiber sensors
  • Relative humidity (RH)

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering

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