Optical fibres based on phosphosilicate glass

The homogeneous chemical vapour-deposition technique, developed for the preparation of phosphosilicate glass fibres, is described. The properties of the binary phosphosilicate glass are outlined and details of preform fabrication and fibre drawing are given. Multimode graded-index fibres have been produced in lengths up to 4km, with numerical apertures up to 0.25, attenuations as low as 2 dB/km and with pulse dispersions of below 1ns/km depending on the source used. Single-mode fibres have also been made with attenuations close to that of pure bulk silica at the design wavelength and with a pulse dispersion of less than 0.1ns/km