Influence of grating fabrication on radiation sensitivity of fiber Bragg Gratings

Fiber Bragg Gratings (FBGs) are candidates for a number of applications in space-borne systems not only owing to their optical functionality but also because they have low mass, small dimensions, and because they are immune to electromagnetic interference. In the case of Earth observation and telecommunication satellites the multiplexing in the optical domain, based on the FBGs, allows a significant reduction of the complexity of on-board electronic systems. Another perspective domain is the fiber sensor systems, such as strain sensors integrated into fuel tanks or structural health monitoring of large space structures. In order to be actually used in space-born systems, FBGs must demonstrate a high stability of their properties over the whole mission time. However, radiation may affect its properties. The possible ways of improving the radiation tolerance of FBGs should be researched. The influence of grating fabrication on radiation sensitivity of the FBGs has been investigated experimentally in this paper. The FBGs were fabricated in different process and GeO₂ concentrations. Pre-irradiation and H ₂-loading were applied to change the radiation sensitivity of the FBGs. The FBGs were fabricated in photosensitive fiber and coupling single mode fiber with a GeO₂ concentration in a range from 0.33 to 23 mol%. The lowest Bragg wavelength shift (13 pm) was obtained by a grating written in photosensitive fiber PSF-GeB-125, with pre-irradiation and without H ₂-loading for a total dose of about 50 kGy.