Experimental investigation of pre-irradiation effect on radiation sensitivity of temperature sensing fiber Bragg gratings

The effect of pre-irradiation on radiation sensitivity of fiber Bragg gratings (FBGs) is verified experimentally. FBGs are fabricated in photosensitive optical fibers and single mode fibers with Ge-concentration in a range from 3 mol% to 23.37 mol% in the core. In experiments, the FBGs are subjected to twice γ-radiation exposures to a Co⁶⁰ source at a dose-rate of 0.1 Gy/s up to a total dose of 50 kGy. Pre-irradiation treatment can reduce the temperature sensitivity variation of FBGs by 18.12%-35.91%, as well as Bragg wavelength shift (BWS) by 8%-27.08 %. Our research demonstrates that pre-irradiation treatment is a feasible method to improve the radiation tolerance of FBGs.