Improvement of radiation resistance of multimode silica-core holey fibers

Abstract

Initial and radiation-induced optical loss spectra of multimode pure-silica-core holey fibers drawn at different regimes are analyzed and compared with those of a conventional POD-fiber with the same KU-1 silica in the core. It is shown that by filling the holes with H 2 gas during fiber drawing, it is possible to fully suppress the drawing-induced 630 nm absorption band and to lower the amplitude of the radiation-induced 610 nm absorption band. The results of an experiment are discussed in which H 2 gas was conducted through the holes of a multimode pure-silica-core holey fiber immediately in the process of its γ-irradiation. The dose evolution of the 610 nm absorption band and of the short-wavelength (≤ 550 nm) absorption associated with hydrogen incorporation into the glass network is analyzed. It is concluded that H 2 gas is efficient at suppressing the 610 nm band in pure-silica-core holey fibers, but can cause a loss increase in the short-wavelength region, in case its pressure in the holes is not sufficiently high.