Feasibility of radiation dosimetry with phosphorus-doped optical fibers in the ultraviolet and visible domain

We investigated the feasibility of using phosphorus-doped optical fibers to monitor the levels of deposited dose during an irradiation. For this, we characterized their spectral and time dependence of the steady state 10 keV X-ray radiation-induced attenuation in the ultraviolet and visible range of wavelengths (200 nm- 900 nm). Their radiation sensitivity is very high with losses exceeding 10 dB m−1 for doses larger than 10 Gy and wavelengths shorter than 550 nm. Our results reveal a sub linear dose dependence of the induced losses that also depends on the dose rate (1 Gy s−1-50 Gy s−1) between 350 nm and 900 nm. For this spectral domain, excess of attenuation is due to the phosphorus oxygen-hole centers. P2 defects are responsible for the induced losses around 300 nm that linearly increase with the dose at least until 1 kGy and without dose rate effect. We measured no noticeable influence of the temperature (5 °C-50 °C) on the radiation-induced attenuation in the studied spectral domain. Our study shows that dosimetry with phosphorus-doped fibers seems possible in the ultraviolet (around 300 nm) with a sensitivity enhanced by a factor N100 compared to the one observed in the infrared region (>900 nm).