| 摘要 |
PURPOSE:To produce the title optical fiber without any crystallite structure and with less light scattering loss by separately casting plural fluoride cylindrical glasses having different compositions and inner diameters, concentrically inserting the glasses, zone-heating the glasses, and drawing the glasses. CONSTITUTION:When an optical fiber consisting of the plural layers of the fluorides such as ZrF4, BaF2, LaF3, and GaF3 is produced, molten fluoride glass 5 is poured into the groove 4 of the cylindrical casting molds 3 having respectively different inner diameters and cast, and fluoride glass pipes 2A, 2B, and 2C of the structures not crystallizing by the quenching of the casting mold 3 are formed. The glass pipes are concentrically inserted into one another, the assembly is placed in a zone-heating furnace 11 provided with a heater 12 at the lower part, the assembly is successively melted from the lower part, and the assembly is drawn into a fiber 13 wherein the fluoride glasses 2A, 2B, and 2C are integrated. In this case, another fluoride glass 2D can be further arranged at the central part. Since the glass pipes 2A-2D are separately cast, quenched, and produced, the product is not crystalline, hence crystallites are not present in the obtained optical glass fiber 13, and the fluorine glass fiber without any light scattering loss and having excellent photoconductivity can be obtained. |
