Plasmon-Enhanced Refractometry Through Cladding Mode Excitation by a Fiber Bragg Grating in Photonic Crystal Fiber

Olga Rusyakina, Tigran Baghdasaryan, Karima Chah, Pawel Mergo, Hugo Thienpont, Christophe Caucheteur, Francis Berghmans, Thomas Geernaert

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)
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We report on an extrinsic surface plasmon-enhanced refractometer based on cladding mode resonance excitation in a photonic crystal fiber (PCF) equipped with a straight fiber Bragg grating (FBG). First, we show that the lattice pitch and the air hole diameter of the PCF microstructure define the spectral location of the excited cladding mode resonances. Second, we demonstrate that if the PCF parameters are properly selected, those resonances are sensitive to increases in steps of 1x10-4 refractive index units (RIU) of the refractive index value close to that of water. To the best of our knowledge, this is the first time that the sensitivity of PCF cladding mode resonances to refractive index changes in water-based solutions is reported. We achieved experimental values of 40.3 nm/RIU in terms of wavelength sensitivity and -801 dB/RIU in terms of amplitude sensitivity. The performance of our sensor is therefore comparable to that of tilted FBGs in step-index fibers used for water refractometry, which indicates the potential of our PCF sensor for biosensing. In addition, the sensor fabrication does not require any post-processing such as etching or polishing, which allows preserving the integrity of the fiber probe. Finally, the narrow spectrum within which the PCF operates, allows envisaging multi-target detection with a single fiber probe by using cascaded wavelength-multiplexed gratings.
Original languageEnglish
Pages (from-to)1121-1129
Number of pages9
JournalJournal of Lightwave Technology
Issue number4
Publication statusPublished - 15 Feb 2022

Bibliographical note

Funding Information:
This work was supported in part by Fonds Wetenschappelijk Onderzoek (FWO) underGrantsG0F6218N (EOS-convention 30467715), 12P1720N, and I013918N; in part by Interreg under Grant NWE758 (Fotonica pilootlijnen).

Publisher Copyright:
© 1983-2012 IEEE.

Copyright 2022 Elsevier B.V., All rights reserved.


  • Fiber bragg gratings
  • fiber optics sensors
  • photonic crystal fibers
  • refractive index measurement
  • surface plasmon resonance


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