Near infrared radiation induced attenuation in P-doped and Al-doped optical fibers at cryogenic temperature

This manuscript presents a study on the effects of cryogenic irradiation on P-doped and Al-doped optical fibers, focusing on radiation-induced attenuation (RIA) when exposed to gamma radiation in the near-infrared (NIR) telecom wavelength 1550 nm. Results are compared to those obtained at room temperature under equivalent conditions. A novel P-doped fiber from the Israeli Institute for Advanced Photonics (ICAP) was tested for what we believe is the first time, along with commercially available P- and Al-doped optical fibers. All results are explained in terms of the defects that are associated with specific spectral ranges of each fiber chemistry. Results from the P-doped fiber show no recovery at room temperature and slight opposite recovery at cryogenic temperatures. The Al-doped fiber showed a slight recovery at both room and cryogenic temperatures. A kinetic model was used to extrapolate data up to higher doses, revealing higher RIA at cryogenic temperatures for both fiber types, with P-doped fiber exhibiting a 100% increase in expected saturation dose at cryogenic temperatures. By reporting the first experimental measurements of cryogenic RIA in P-doped and Al-doped fibers, this study sheds light on the underlying defects responsible for RIA at cryogenic temperature and represents an initial step toward developing in-situ cryogenic radiation dosimeters for nuclear fusion reactors, particle colliders, and space missions.