Development and performance of fully fluorine-doped single-mode fibers

Fluorine doping has been used to obtain vapor-phase-axial-deposited (VAD) single-mode fibers with a loss less than 0.20 dB/km at 1.55 mu m. A nonshifted design in which fluorine dopant was added mainly to the cladding and only slightly to the pure silica core part was fabricated with high yield. A similar approach has been successfully applied to dispersion-shifted fibers with a dual-shape-core index profile with encouraging results for reducing the transmission loss down to 0.20 dB/km.< >