Patent ID: 7630611

Claim:
An optical fiber comprising a cladding layer and a light conducting core, wherein the optical fiber is manufactured by: i) supplying one or more glass forming precursors to a substrate tube; ii) supplying a stoichiometrically excess amount of oxygen to the substrate tube; iii) bringing about a reaction in the substrate tube between reactants supplied in i) and ii) so as to deposit one or more layers of glass on an interior of the substrate tube; iv) subjecting the substrate tube thus formed in iii) to a collapsing treatment so as to form a preform; and v) drawing an optical fiber from the preform formed in iv) while heating, and subsequently cooling same, wherein vapor deposition reaction in iii) is carried out in such a manner that the amount of oxygen supplied to the substrate tube in ii) is maximally 3.5 times a stoichiometric amount, wherein the light conducting core is doped with GeO 2 and fluorine and an amount of Cl in the light conducting core ranges between 500 and 3000 ppm, and wherein a total attenuation of light transmission at 1550 nm, including hydrogen-induced attenuation, is maximally 0.25 dB/km.