Regular ArticlesMetal-coated Bragg grating reflecting fibre

- Development of a new fibre optic temperature and mechanical tension sensors and increasing of their operating range are a hot topic for research.
- Usually it's used point fibre Bragg grating (FBG) for such applications additionally FBG arrays were used for distributed type sensors.
- In this study, we show for the first time, that it is possible to produce optical fibres with the recorded array of FBG in-line during the fibre drawing process with metal coating, instead of the polymer coating as previously.
- Metal coating allows us extend the upper working temperature of FBG array from 125 C to 600 C.
- Furthermore, it was found that arrays of aluminum coated FBG are not erased by high temperature heat (600 C).
- Another important point is that developed fibre had the same mechanical strength as fibre without FBG.

High-temperature optical fibres (OF) with fibre Bragg gratings (FBG) arrays written over a long length and in-line metal coating have been made for the first time. The optical parameters of the FBG arrays were tested by the optical frequency domain reflectometer (OFDR) method in a wide temperature range, demonstrating no degradation in reflection at heating up to 600 °C for a fibre with Al coating. The mechanical strength of the developed fibre was practically the same as “ordinary” OF with similar coating, showing the absence of the influence of FBG writing process on fibre strength. Further experiments are necessary to evaluate the possibility of further increases in the operational temperature range.