Method for producing an optical preform with a POD cladding glass layer

摘要

The invention relates to a plasma deposition process for producing an optical preform, which is characterized by a cladding glass layer having a non-round internal cross-section together with high fluorine doping and axially and radially specified dopant distribution, which in the simplest case is as uniform as possible. For this purpose, a two-stage method is proposed, wherein a substrate body having a non-round cross-section is first reshaped into a coated substrate body having a circular cross-section in that a POD filling layer made of quartz glass having the nominal fluorine concentration is deposited onto a present filling surface and rounded by grinding, and then in the second stage of the method a POD sheathing glass layer made of fluorine-doped quartz glass and having a circular-ring-shaped cross-section is deposited.

主权项

1. A method for producing an optical preform with a POD cladding glass layer of fluorine-doped quartz glass, said method comprising:
forming SiO2 particles with a plasma burner in the presence of fluorine, depositing said SiO2 particles on an outer cylinder surface of a cylindrical substrate body having a longitudinal axis, and vitrifying said particles directly, said substrate body having a non-round cross-section taken perpendicular to the longitudinal axis including at least one surface section that extends between support points of an enveloping circle of said cross-section and that either has no curvature or has a curvature that is different from the curvature of the enveloping circle, wherein the forming, depositing and vitrifying steps include: (a) producing a POD filling layer of quartz glass with fluorine in a nominal concentration on said surface section, so as to form a coated substrate body, said coated substrate body having a circular cross-section having a radius that is at least as great as a radius of the enveloping circle; and (b) depositing a POD enveloping glass layer having a of circular cross-section, said POD enveloping glass layer being of fluorine-doped quartz glass on the coated substrate body.