Heraeus Quarzglas Gmbh & Co Kg

Furukawa Electric North America, Inc.

Heraeus Quarzglas Gmbh

Heraeus Tenevo Gmbh

Norbert Treber

Hartwig Schaper

Heinz Fabian

Helmut Leber

Karsten Bräuer

Gerhard Schötz

Klaus Reimann

Donald Jablonowski

Gerhart Vilsmeier

Oliver Humbach

Uwe Haken

In a known method for the production of a blank mold for optical fibers, a fluorine-doped SiOenveloping glass is produced on a core glass cylinder that rotates about its longitudinal axis, wherein a silicon-containing starting substance is fed to a plasma burner, said substance is then oxidized in a plasma flame assigned to the plasma burner to obtain SiOparticles, the SiOparticles are deposited by layers on the enveloping surface of the cylinder of the core glass cylinder in the presence of fluorine and sintered into the enveloping glass. The invention aims at providing an economical method, which builds upon the above-mentioned method, in order to produce a blank mold from which optical multi-mode fibers () can be obtained. In comparison with fibers () produced according to standard methods, said optical multi-mode fibers are characterized by high initial transmission in the UV wavelength range and good resistance with respect to brief UV radiation, more particularly in the 210-300 nm wavelength range. According to the invention, a plasma flame that irradiates an ultraviolet light having a wavelength of 214 nm with an intensity of at least 0.9 ?W&#x2014;determined on the basis of plasma flame intensity measurement&#x2014;is used for the formation and deposition of the SiOparticles on the core glass.

Method for the production of a blank mold for optical fibers

On the basis of a known process for the production of a preform for an optical fiber for optical data transmission technology, the productivity of the process for the production of complex refractive index profiles is to be improved by providing a quartz glass substrate tube which exhibits different doping in radial direction, introducing a core glass made of synthetic quartz glass into the substrate tube and covering the substrate tube with a jacket tube. A substrate tube suitable therefor is also being provided which tube requires less core glass material for the production of the preform, whether during the internal deposition or for the core glass rod in the rod-in-tube technique. Regarding the process it is proposed according to the invention that a substrate tube be used which was obtained by vitrification of a porous tube-shaped SiOblank, the substrate tube being provided with a core glass layer which is produced in that to the first radial portion of the SiOblank there is added before the vitrification a first dopant which increases the refractive index of quartz glass. The substrate tube according to the invention has in the radial direction regions of different doping whereby it incorporates a core glass layer which has a refractive index of at least 1.459.

Method of making a jacketed preform for optical fibers using OVD

Starting from a process for producing a rod-like preform, in particular for optical fibers, in which a tubular blank whose refractive index changes, viewed in the radial direction is fed to a heating zone, is softened there, and in the softened state is shaped to give the preform, a method is described for producing preforms which are hyperpure and low in defects, in which the blank used is one whose refractive index decreases, viewed in the radial direction, from the outside inwards, starting from at least one interface which is at a sufficient distance from the outer surface of the blank, of which that part which has been softened in the heating zone is introverted apart from an outer skin, and by which the preform is formed in the longitudinal axis of the tubular blank, counter to the direction in which the latter is fed to the heating zone, and in which the remaining outer skin is drawn off as a rod in the feed direction of the blank.

Method of partially introverting a multiple layer tube to form an

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Hanau, Germany

Norbert Treber