Patent ID: 6523369
Filing Date: 2003-02-25
Classification: C03B,C03C

Abstract:
A method of forming a optical fiber comprising the steps of:(a) providing in solid form a glass doping constituent having an exposed two dimensional surface of predetermined length and width; (b) exposing the constituent to a substantially oxygen free ambient with a temperature sufficient to vaporize the constituent from the exposed two dimensional surface to form a constituent laden vapor; (c) introducing into a reaction zone a glass forming vapor contemporaneously with the constituent laden vapor, the reaction zone including a bore tube; (d) elevating the temperature of the reaction zone to form at least one porous or particulate layer on a surface of the bore tube deposited from the glass forming and the constituent laden vapors; (e) solution doping the porous or particulate layer to imbibe the dopant solution into the layer; (f) collapsing the bore tube under an elevated temperature to form a fiber preform comprising at least a preform core having an index of refraction n1 disposed within a multi-mode cladding having an index of refraction n2, the multi-mode cladding being the previously formed porous or particulate layer; (g) depositing onto the optical fiber preform a further cladding having an index of refraction n3 surrounding said multi-mode cladding wherein n1>n2>n3; and (c) drawing an optical fiber from the optical fiber preform.