Patent ID: 7089765

Claim:
A process for the production of an optical fiber preform for optical data communications, said process comprising: providing a tubular porous SiO 2 blank having a first radial portion containing a first dopant that increases the refractive index of quartz glass, said providing including forming said porous SiO 2 blank by an outside vapor deposition (OVD) process, which includes forming the first radial portion by outside vapor deposition; vitrifying the tubular porous SiO 2 blank so as to form a substrate tube which has in the radial direction different dopants and such that the fist radial portion is formed into an inner glass layer of the substrate tube, said inner glass layer containing said first dopant and having a refraction index of at least 1.459; introducing in the substrate tube a core of synthetic quartz glass and collapsing the substrate tube so as to form a collapsed substrate tube containing said core; and placing a jacket tube around the collapsed substrate tube, and collapsing the jacket tube so as to form the optical fiber preform.