Radiation hardening of pure silica optical fibers by high-pressure hydrogen treatment

It was proved that hydrogen (H₂) treatment, consisting of loading with H₂ under high pressure and immediate pre-irradiation up to dose values ≥ 10⁴ Gy considerably increases the radiation hardness of optical fibers with a pure SiO₂ core, especially of those with a low OH content. These fibers even show a reduction of their initial attenuation at wavelengths < 700 nm, in contrast to a significant increase between 1200 and 1600 nm (growth of OH absorption bands). Therefore, H₂ treatment should be restricted to fiber applications in the visible wavelength range, up to about 850 nm. A treatment with highly enriched deuterium should extend the usefulness to wavelengths around 1300 nm.