Radiation-induced attenuation (RIA) in undopedsilica-core optical fibers of which the preform cores are synthesized in high O 2 excess conditions in the vapor-gas mixture ("high oxygen excess fibers, HOE-fibers") is investigated in the spectral range 1.1-1.7 µm under γ-irradiation from a 60 Co-source. The O 2 excess degree, the F content in the cladding, the drawing speed and tension are varied among the fibers. RIA is found to strongly depend on the balance between the O 2 excess degree in the core and the F content in the cladding and also on the fiber drawing tension. RIA anticipated in HOE-fibers with optimized O 2 excess and a practicably low drawing tension at λ=1.55 µm is estimated to be a few times lower than that in the commercial radiation-resistant F-doped-silica-core fibers.Index Terms-Optical fiber radiation effects, optical fiber radiation resistance, radiation-induced attenuation (RIA).

No abstract

Single-mode Er–Yb fibers with the core based on a phosphorosilicate glass matrix (up to 6.5 mol.% P2O5) highly doped with fluorine (up to 0.9 wt.%) were fabricated using an all-gas-phase modified chemical vapor deposition method. The core numerical aperture was in the range of 0.07–0.08 relative to the pure silica, which allowed us to increase the single-mode core diameter up to 20 μm. The slope efficiency in lasers based on the fabricated fibers reached 34% relative to the launched pump power.

IR luminescence and optical gain in a Pb-doped fiber have been observed for the first time. Absorption, luminescence and pump on/pump off optical gain spectra, as well as luminescence decay time, have been measured in these fibers. Comparison of optical active center characteristics in Pb-doped and Bi-doped fibers of the same composition indicates an essential difference of optical active centers in these two types of fibers.