Patent ID: 8720230

Claim:
A method for fabricating a preform for use in manufacturing an optical fiber that has least one core, the method comprising: pouring SiO 2 -particles into an interior space of a silica tube, the silica tube having an interior space that is limited at a lower end thereof by a closure made of a porous material such as porous glass; introducing a flow of a gas selected from the group consisting of oxygen (O 2 ), helium (He), chloride (Cl 2 ) and fluorine (F), through the closure and through the SiO 2 -particles contained in the silica tube; heating the silica tube to a temperature below the vitrification temperature of the silica tube in order to purify and calcinate the SiO 2 -particles; attaching an adjoiner to an upper end of the silica tube; generating a reduced pressure within the interior space of the silica tube; and heating at least a bottom portion of the silica tube to a temperature above the vitrification temperature of the silica tube in order to fuse the silica tube and the SiO 2 -particles.