Continuous optical fiber preform fabrication method

Abstract

A refractory starting member is rotated and, at the same time, moved along the axis of rotation. A glass raw material for the formation of the core of a porous preform and consequently an optical fiber preform is introduced into a high temperature portion near the tip of a high temperature burner from a nozzle for the core disposed in alignment with the center of rotation of one end face of the starting member. The glass raw material blown out from the nozzle for the core are caused by the flames of the high temperature burner to react to produce glass fine particles, which are deposited on abovesaid end face of the starting member at the central portion thereof in its axial direction to form a porous core. At least one nozzle for spraying a glass raw material for the formation of the cladding of the optical fiber preform is disposed opposite to the end face of the starting member but a little deviated from the axis of rotation thereof, or disposed opposite to the peripheral surface of the porous core. The glass raw material for the cladding is sprayed from the nozzle for the cladding to the high temperature portion of the high temperature burner, and caused to react to form glass fine particles, which are deposited on the end face of the starting member on the outside of the porous core or on the peripheral surface thereof at the same time as the formation of the latter, forming a porous cladding. The porous preform thus obtained is moved into a high temperature furnace provided on the path of movement of the preform for the vitrification thereof into an optical fiber preform.