The Post Office

British Telecommunications Public Limited Company

British Telecommunications Corporation

Clive R Day

Keith J Beales

Benjamin J Ainslie

John Edwin Midwinter

George R Newns

James D Rush

An improved method of manufacturing an optical fibre by vapor phase deposition of layers of cladding and core material for an optical fibre on the inside of a tubular substrate, followed by heating of the tube to cause it to collapse into a preform and drawing of the preform to form the fibre, includes performing the collapse with the introduction of chlorine gas acting as a drying agent. An alternative to chlorine gas is a vapor which decomposes in situ to yield chlorine without producing a solid deposit.

Glass fibres and optical communication

An optical fibre capable of monomode transmission in, and having a wavelength of zero dispersion in, the 1.55 .mu.m window and having a core comprising silica and germanium dioxide and a cladding comprising silica is drawn from an appropriate preform at a temperature in the range from 1900.degree. C. to 2000.degree. C. Fibres thus produced have low loss compared with fibres drawn at higher temperature.

Optical fibres

A graded index optical fiber is produced in a double crucible with an elongate heated exit nozzle. The core and cladding glasses of the fiber diffuse into one another in the nozzle.

Method for manufacture of graded index optical fibres

An apparatus for drawing a dielectric optical waveguide having minimal attenuation characteristics comprises a double crucible in a closed atmosphere container with glass rod supply means and atmosphere supply means.

Drawing dielectric optical waveguides

The attenuation in a dielectric optical waveguide can be reduced by the following techniques:

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Woodbridge, United Kingdom

Clive R Day