Temperature Dependence of the Radiation Response of Ultralow-Loss Optical Fibers: Role of Self-Trapped Holes

We investigated the temperature (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$- 60~^{\circ }$ </tex-math></inline-formula>C, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$20~^{\circ }$ </tex-math></inline-formula>C, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100~^{\circ }$ </tex-math></inline-formula>C) dependence of the X-ray radiation-induced attenuation (RIA) in the visible (VIS) to infrared (IR) spectral domain of an ultralow-loss (ULL) pure-silica core (PSC) single-mode optical fiber (OF). This fiber was shown to be very radiation-sensitive at room temperature (RT) with extremely high RIA levels in the whole spectral domain. The RIA levels and kinetics exhibit a strong dependence on the temperature of irradiation. The nature and the properties of the radiation-induced point defects at the origin of the fiber darkening are discussed, in particular, the influence of the different variants of the self-trapped holes (STHs). STHs play a key role in the response of this class of OF as in the ones of the most advanced radiation-hardened OFs.