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Effect of high temperature on the properties of long-period gratings written in non-hydrogenated fibers with UV and electric arc

This work presents the effect of high temperature (~350°C) on the performance of the LPGs written in non-hydrogenated standard fiber (Corning SMF28) and in photosensitive fibers (Fibercore PS1250/1500 and Nufern GF1) using UV exposure and electric arc discharge. The effect is discussed from a point of view of application of the gratings as platforms for high-temperature overlay deposition to enhance sensing properties of such LPGs. Our experiment shows that only arc-induced gratings are suitable for high-temperature coating deposition and high temperature processing up to 350°C. It is shown that the temperature induced degradation effect for UV-written LPGs does not depend on composition of the core of the fiber and takes place for both photosensitive fibers. Moreover, for the LPG written in GF1 fiber the spectrum does not shift when the sample is cooled down, but stays the same as it was at the higher temperature.