Distributed Optical Fiber-based Dosimetry with Optical Frequency Domain Reflectometry

We demonstrate a real-time high-spatial-resolution (3 cm) ionizing dose 2-D mapping sensor achieved by analyzing a phosphorus-doped silica-based optical fiber with a Rayleigh-Optical Frequency Domain Reflectometry (R-OFDR) interrogator. The dose is monitored through the radiation induced attenuation (RIA) around 1550 nm measured on the OFDR traces. This study aims at studying the sensor performances and to assess its dose mapping capabilities. The RIA spectrum from the P-doped fiber is first characterized and the fiber radiation sensitivity is calibrated by evaluating the dose-rate. Then, the dose-rate dependence (from 10 mGy/s up to 4 Gy/s) of the RIA levels and kinetics has been investigated up to a cumulated dose of 2 kGy(SiO 2 ). The achievable spatial RIA resolution with the R-OFDR is equal to 3 cm for precise distributed measurements. Finally, a 2-D square mapping of our X-ray beam has been performed during irradiation with a 10 s acquisition period. These results highlight the significance of distributed and active R-OFDR dosimetry for doses up to 2 kGy, as well as beam shape sensing with high spatial resolution.