Effects of hydrogen loading on optical attenuation of gamma-irradiated UV fibers

Three types of commercially available optical fibers operating in UV (a deep UV enhanced, high OH, step-index, multimode optical fiber; a solarization resistant, high OH, step-index, multimode optical fiber; a UV enhanced, extended spectral response, H2-loaded, step-index, multimode optical fiber) were tested under gamma-ray irradiation, all optical fibers having a Polyimide buffer. Investigations were carried out at room temperature, and in some situations, the optical fibers were heated up to 573 K during the irradiation, in order to check the effect of heating on color center generation. The dependency of the optical attenuation as function of the total dose, and temperature, at specific wavelengths (λ = 248 nm, λ = 265 nm, λ = 320 nm and λ = 330 nm) was measured. H2-loading optical fibers improves the radiation resistance to gamma irradiation for the wavelengths of λ = 248 nm and λ = 265 nm. Heating during the irradiation in the case of H2-loaded optical fibers with Polyimide buffer decreases the radiation resistance of the optical fiber, as a result of outwards H2 diffusion. A higher radiation sensitivity and a linear dependency of the optical attenuation as function of the total dose was observed for solarization resistant sample.