Investigation of Ge/P-Doped Silica Optical Fibers for Radiation Sensing

The Distributed Optical Fibre Radiation Sensor (DOFRS) developed by CERN is a key technology for the spatially continuous and real-time monitoring of radiation dose in harsh environments. Silica-based optical fibres (OFs) doped or co-doped with phosphorous are used as sensing elements of the DOFRS systems. The performance of these systems is strongly dependent on the radiation sensitivity of the OFs used, as well as the possibility to qualify and calibrate them for dosimetry applications. In this article, we report on the radiation response of a set of twelve Ge/P-doped single-mode OFs at 1550 nm and 1625 nm under 60 Co γ-rays, including a post-irradiation study to evaluate the recovery of the fibres under test. After conducting several experiments to evaluate the performance of the OFs, we determined which ones are the most suitable to be used in the radiation sensing fibre optics cables installed in CERN's accelerator complex.