Comparison of Gamma-Radiation Induced Attenuation in Al-Doped, P-Doped and Ge-Doped Fibres for Dosimetry

We have investigated radiation induced absorption in Al-doped, P-doped and Ge-doped optical fibres under $^{60}$ Co source gamma-radiation up to a total dose of 71 kGy at two temperatures 30 and 80$^{\circ}$ C. The Al-doped and P-doped fibres demonstrated high radiation sensitivity required for the optical fibre dosimetry. The RIA response to temperature increase from 30 to 80$^{\circ}$ C depended on the dopant. In Al-doped fibres the absorption level decreased by 25% whereas in P-doped fibres it increased by at least 10%. For comparison we also tested standard telecom-grade Ge-doped fibres. Such fibres demonstrated a monotonous rise of the RIA during the whole irradiation with a small decrease of sensitivity at the higher temperature.