Production of a preform used for optical fibers comprises introducing oxygen into a reaction zone of a burner to convert the starting components into oxide particles

摘要

Production of a preform comprises feeding a first starting component containing silicon and a second starting component forming a dopant to a burner in a central region and a fuel gas in an outer region with a separating gas stream being fed between the central and outer regions. The starting components are converted to oxide particles using flame hydrolysis in a reaction zone and deposited on a rotating support forming a porous blank containing silicon and the dopant. Oxygen in a over-stoichiometric amount is introduced into the reaction zone and to convert the starting components into oxide particles. An oxygen stream is used as the separating gas stream. The reaction zone starts in a region which is surrounded radially by a gas feed sleeve. Preferred Features: The gas feed sleeve extends from the start of the reaction zone over a length of 5-60 mm in the direction of the blank.