Potential of Germano-Phosphosilicate Single-Mode Optical Fibers for Dosimetry

We study the near-infrared (NIR) radiation-induced attenuation (RIA) of a single-mode (SM) optical fiber composed by a Ge-doped core, a ~4-
$\mu $
m-thick P-doped inner cladding and pure Silica outer cladding. Its potential for dosimetry application has been investigated by spectral RIA measurements. The RIA, measured at 1550 nm, exhibits a linear growth as a function of the accumulated dose up to ~1 kGy(SiO2). The sensitivity to radiation, expressed by the coefficient
$\xi $
, results in 164 mdB km−1 Gy−1 in the 0–1 kGy dose range, ~24 times lower than the one of an SM P-doped optical fiber. Furthermore,
$\xi $
almost does not depend on the dose-rate, its variation remains on the order of 6% (10 mdB km−1 Gy−1) for the dose-rate range from 10 mGy s−1 up to 10 Gy s−1. At wavelengths lower than ~1450 nm, our measurements reveal a stronger dose rate dependence and less interesting dosimetric properties. Finally, a preliminary test on the 1550 and 1625 nm RIA at different irradiation temperatures (from room temperature to 90 °C) showed no significant changes in the
$\xi $
radiation sensitivity coefficients.