Abstract: A method and manufacturing apparatus for forming one or several material layers inside a basic tube, which basic tube is used in the manufacture of an optical fiber preform. The surface inside the basic tube is electrically charged by guiding a first electrically charged gas flow inside the basic tube, whereafter a second electrically charged gas flow is guided into the basic tube. The gas flow contains material particles and the sequentially alternating first gas flow and second gas flow have opposite charges.

Abstract: A method for charging particles used for processing of a material. At least a gaseous reactant is supplied and oxidizing gas is supplied to the reactant. The oxidizing gas is charged electrically before it is supplied to the reactant. The reactant and the oxidizing gas form charged particles. The material to be processed is advantageously a multicomponent oxide construction, such as an optical fiber preform. The invention also related to a charging device implementing the method.

Abstract: The invention relates to the production of light-amplifying optical material. Liquid reactant is atomized into droplets using a high velocity gas. The droplets are subsequently introduced into a flame. Reactants are oxidized in the flame and condensed by forming small particles. At least a fraction of said particles is collected and fused to form optical waveguide material, which is subsequently drawn to form an optical waveguide. According to the invention, the velocity of the atomizing gas stream is in the order of the velocity of sound. The high velocity enhances atomization and increases reaction rates in the flame. The residence times are reduced to such a degree that unwanted phase transformations in the produced particles are substantially minimized. Consequently, very homogeneous material is produced. Especially, in the production of erbium-doped silica, low percentage of clustered erbium ions is achieved.

Abstract: A preform, a head part for a preform and a method for manufacturing a fiber. The head part is adapted to be attached to a preform of a fiber. The head part has such a shape that a heat load directed to the preform will be distributed to the cross section of the bulk part in a predetermined manner, like evenly distributing the heat load to the cross section of the preform. When manufacturing a fiber from a preform including such a head part the heating of the preform is more controllable thus resulting in a fiber with a better quality.

Abstract: A method for preparing doped oxide material, in which method substantially all the reactants forming the oxide material are brought to a vaporous reduced form in the gas phase and after this to react with each other in order to form oxide particles. The reactants in vaporous and reduced form are mixed together to a gas flow of reactants, which gas flow is further condensated fast in such a manner that substantially all the component parts of the reactants reach a supersaturated state substantially simultaneously by forming oxide particles in such a manner that there is no time to reach chemical phase balances.

Abstract: The invention relates to a method and a device in the manufacture of an optical fibre (11), in which manufacture a fibre preform (12) is placed vertically in a drawing furnace (10) or the like, in which drawing furnace (10) the preform (12) is heated in a heating zone in such a way that a thin fibre (11) is formed of the molten zone (16) forming at the lower end of the preform (12) by means of gravity and/or downwards drawing of the fibre (11), and the forming fibre (11) is guided to cool down in a controlled manner in an extension tube (19) following the healing zone. According to the invention, after said heating zone, on the path of the molten or still partly molten fibre (11), the extension tube (19) is provided with a thermophoretic collector (20, 30, 40) which comprises one or more cooled means (21, 31, 41) to thermophoretically deposit, on its surface, impurities contained in the gas flow (18) surrounding the fibre (111).

Abstract: A system and a method in producing a doped glass material, particularly a glass material to be used in light amplifying optical waveguides. The method comprising: bringing at least a first dopant and a second dopant of the glass material into a vaporous gas phase; controlling the vapour pressure of the gas phase of each dopant by bringing each dopant to a desired temperature which is simultaneously used to control the composition of their gas phase; and mixing each vaporous dopant with the gas flow of the basic material for the glass material, which basic material is also in a gas phase and is used as a carrier gas for the dopants, wherein said basic material and said dopants together constitute the required gas flow of so-called reactants, to be used for producing the glass material; performing the mixing so that said dopants are each mixed in turn with the same gas flow of the basic material in such an order that said desired temperatures of the dopants are increasing in relation to one another.

Abstract: A heating apparatus for preparing an optical fiber from a preferably vertical fiber preform in a draw furnace, in which draw furnace the fiber preform is heated with the heating apparatus in the heating zone of the draw furnace in such a way that a molten, downwards tapering zone is formed in the preform, from which a thin fiber is produced by means of gravity and/or drawing the fiber downwards, which heating apparatus comprises at least a preferably tubular heating element, placed around the fiber preform in the draw furnace, for heating the fiber preform, and a heating means placed around the heating element in the draw furnace, for heating the heating element, as well as an insulator element around the heating element. The heating element and the insulator element are surrounded at least partly by a radiation shielding to reflect thermal radiation from the heating element to the insulator element back to the heating element.