High-sensitivity optical fiber refractive index sensor using multimode interference structure

Hideki Fukano, Yoshiki Matsumoto, Shuji Taue

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


This letter presents the experimental investigation to increase the sensitivity of an optical fiber refractive index sensor with a multimode interference (MMI) structure. It is confirmed that the interference wavelength can be set in the long-wavelength region by adjusting the sensing-part length. Moreover, it is shown that the fineness of the cores in the input and output fibers is essential to obtain a sharp interference signal. We demonstrate the high sensitivity of an MMI-structured optical fiber sensor by applying it to refractive index measurements of ethanol/water solutions. This refractive index sensor reveals a resolution as fine as 1.8 × 10 -5, which is the highest value so far reported in this type and has one order higher sensitivity than a commercially available Abbe refractometer (~ 10 -4).

Original languageEnglish
Pages (from-to)302-306
Number of pages5
JournalIEICE Electronics Express
Issue number4
Publication statusPublished - 2012


  • MMI
  • Multimode interference
  • Optical fiber sensor
  • Refractive index sensor

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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