An optical-transmission error-rate experiment is described in which a single-mode fibre up to 5.9 km long is used as a transmission medium. It is shown that impairments of the transmission was mainly determined by material dispersion and wave-guide-delay distorsion of the transmission medium.

A continuous fabrication process for high-silica fiber preforms has been developed. Unlike the conventional fabrication process, the perform is grown in an axial direction. The process is essentially a soot process. A porous preform is grown in the axial direction by the deposition of fine glass particles synthesized with vapor reaction of raw materials, and is continuously consolidated into a transparent preform by zone-melting. The refractive index profile is controlled in the spatial domain, rather than as a function of time, as in conventional methods. The transmission loss of the fiber made by this method was 2.3 dB/km at 0.85 µm and 0.75 dB/km at 1.2 µm. The bandwidth graded index type fiber was 300 MHzkm as an average. The best value was 1.0 GHzkm. These fibers had good uniformity along the longitudinal direction, both in transmission characteristics and in dimensions.