Method for manufacturing an optical fibre

Abstract

A method for manufacturing a glass core rod and a cladding layer clothing the glass core rod applied successively or continuously by using a carbon dioxide gas laser. A refractory mandrel is heated by means of carbon dioxide gas laser irradiation and a mixed gas of oxygen and pure silicon tetrachloride vapor and a dopant compound vapor is ejected to the refractory mandrel so as to deposit silicon oxide and oxide of the dopant compound on the mandrel and to form a glass core by fusing it. Further heating is applied by irradiation by the carbon dioxide laser beam on the glass core and a mixed gas oxygen and pure silicon tetrachloride vapor and a dopant compound vapor or of oxygen gas and pure silicon tetrachloride vapor to deposit silicon oxide and oxide of the dopant compound or silicon oxide on the glass core to form a cladding layer of fused silica or fused silica containing the dopant. The preform thus formed by the glass core and the cladding is heated above the softening temperature of the preform so as to spin to form an optical fibre. The method uses laser beam heating which results in less degree of contaminating impurity and water content which might cause absorption and scattering of light also to manufacture an optical fiber having less variation at the boundary of the glass core and the cladding layer.