Method for preparing an optical fibre, optical fibre and use of such

摘要

Method for coating an optical fibre with optical fibre Bragg grating (FBG) with a hermetic coating, particularly a coating of carbon, to avoid ingress of gases, vapours or fluids in the ambient environment. This can be water or hydrogen, which can diffuse into the fibre glass and cause deviation/drift in the measured Bragg measurements. Bragg grating that maintain the grating strength at temperatures in excess of 1000° C. is used, which is heated to above 1000 ° C. in a chamber with a reactive gas that produces deposition of carbon.