High-sensitivity and large-dynamic-range refractive index sensors employing weak composite Fabry-Perot cavities

Pengcheng Chen, Xuewen Shu*, Haoran Cao, Kate Sugden

*Corresponding author for this work

Research output: Contribution to journalLetter, comment/opinion or interviewpeer-review


Most sensors face a common tradeoff between high sensitivity and large dynamic range. We demonstrate here an all-fiber refractometer based on a dual cavity Fabry-Perot interferometer (FPI), which possesses the advantage of both high sensitivity and large dynamic range. Since the two composite cavities have a large cavity length difference, one can observe both fine and coarse fringes, which correspond to the long cavity and short cavity, respectively. The short cavity FPI and the use of an intensity demodulation method, mean that the individual fine fringe dips correspond to a series of quasi-continuous highly sensitive zones for refractive index measurement. By calculating the parameters of the composite FPI, we find that the range of the ultra-sensitive zones can be considerably adjusted to suite the end requirements. The experimental trends are in good agreement with the theoretical predictions. The co-existence of high sensitivity and large dynamic range in a composite FPI is of great significance to practical RI measurements.
Original languageEnglish
Pages (from-to)3145-3148
Number of pages4
JournalOptics Letters
Issue number16
Early online date20 Jul 2017
Publication statusPublished - 9 Aug 2017

Bibliographical note

© 2017 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.


  • fiber optics sensors
  • microstructure fabrication
  • interferometry
  • Fabry-Perot resonators
  • all-optical devices


Dive into the research topics of 'High-sensitivity and large-dynamic-range refractive index sensors employing weak composite Fabry-Perot cavities'. Together they form a unique fingerprint.

Cite this