Ceramic coating for optical fiber

In the context of the collaboration agreement between CEA LIST and the CNRS, research is conducted to develop optical fiber sensors in harsh environment (above 800°C). A key point is the development of fiber optic coating capable of withstanding high temperature for the long term. Up to now, metallic coatings can only resist up 700°C for a short term.

Drum of 90m length Optical fiber with-BN coating. Optical image of silica fiber coated with Boron nitride coating. XRD analyses at temperature up to 1100°C in air.

A significant result is the development of a boron nitride-based coating compatible with a fibre tower deposit. Resistance at 800°C in air on long term was demonstrated (test made on 1500h). (900°C for a short term). The coating can be deposited during the drawing process or added in post process on small length (10-250cm). the thickness of the coating is about 7µm, and can be increase in multi-layer deposition in post process.

Optical fiber sensors were manufactured, discussions are underway to assign an operating license to a startup (myriad4sensing), specialized in the development of fiber sensors for harsh environment.

References

[1] Bernard Rémy, Pastre Aymeric, Lago-Rached Laure, Enduction d’une fibre notamment optique par un revêtement à base de nitrure de Bore. FR2207160 / WO2024013066

[2] Bernard Rémy, Pastre Aymeric, Lago-Rached Laure, Lerner Alexandre, Laffont Guillaume, Utilisation d’une fibre optique comprenant un revêtement à base de nitrure de Bore dans un procédé de synthèse additive de structures céramiques. FR3137912