Distributed cladding mode fiber-optic sensor

Gil Bashan, Yosef London, H. Hagai Diamandi, Avi Zadok

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


The analysis of substances outside the cladding has challenged the optical fiber sensors community for decades. A common solution relies on the propagation of light in cladding modes. However, the coupling of light to/from these modes is typically based on permanent gratings in specific locations, which restrict the sensors to point measurements only. In this work, we present dynamic, random-access coupling of light between core and cladding modes of standard fibers, in arbitrarily located short sections. Coupling is based on the stimulation of Brillouin dynamic gratings by two coded pump waves and intermodal scattering of a third optical probe wave. All waves are launched and collected in the core mode. No permanent gratings are inscribed. Distributed sensing of surrounding media is demonstrated with 2 m range and 8 cm resolution. Measurements distinguish between water and ethanol outside the fiber. The measurement accuracy of the local index outside the cladding is 0.004–0.0004 refractive index units.

Original languageEnglish
Pages (from-to)85-92
Number of pages8
Issue number1
StatePublished - 2020

Bibliographical note

Funding Information:
Acknowledgment. The authors thank Dr. Nachum Gorbatov from Tel-Aviv University for his assistance with the characterization of fibers under test. H. Hagai Diamandi is grateful to the Azrieli Foundation for the award of an Azrieli Fellowship.

Funding Information:
European Research Council (H2020-ERC-2015-STG 679228 (L-SID)); Israel Science Foundation (1665-14).

Publisher Copyright:
© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement


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