The fabrication and performance of long lengths of silica core fiber

Three hundred kilometers of single-mode fiber exhibiting median optical losses of 0.19 dB/km at 1.57 μm have been fabricated from preforms made by a high-rate Modified Chemical Vapor Deposition (MCVD) process. A new fiber design [1] was utilized which minimizes Rayleigh scattering loss by reducing the amount of dopants in the core. Milestone systems experiments incorporating this fiber have already demonstrated 420-Mbit transmission through 203 km [2], 2-Gbit transmission through 130 km [3], 1.37 Tbit km/s using 10 wavelength division multiplexed lasers [4], 4-Gbit through 102 km using a novel electronic multiplexer/demultiplexer [5], and 4 Gbit through 117 km using a Ti:LiNbO 3 external modulator [6]. Additionally, very low induced losses from hydrogen and radiation are reported.