Radiation-Induced Attenuation in Standard Optical Fibers at Cryogenic Temperatures: Effect of Photobleaching Wavelength/Energy

The low temperature (cryogenic) irradiation of optical fibers produces severe radiation-induced attenuations (RIA) that limit the functionalities and lifetimes of fiber-based sensors. The RIA at some primary probe wavelength (e.g., 1550 nm) can be mitigated via photobleaching with light of some secondary wavelength (e.g., 1050 nm), increasing the lifetimes of such sensing systems. Herein, we investigated the effects of four different photobleaching wavelengths (1050 nm, 880 nm, 770 nm, and 450 nm) on the RIA growth kinetics and the saturation RIA in standard optical fibers (SMF28e+) irradiated at 15 K. The photobleaching was most effective for 770 nm light and least effective for 450 nm light. The latter was negatively impacted by significant attenuation of the photobleaching light itself. The data were analyzed using a kinetic model, through which the photobleaching rates per input power, as a function of photon energy, were calculated.