Abstract: A processing method of a silica glass fiber, which is applicable to a long fiber, to improve its UV resistance by UV irradiation and heat treatment. Initially, a heating furnace 1 is positioned such that the left end of the silica glass fiber is within the heating furnace 1. Then, the heating furnace 1 is moved toward the right, while UV is irradiated with a UV source to the left end surface of the silica glass fiber. Since the silica glass becomes transparent due to removal of structural defects that have been caused by the UV irradiation, the UV travels further forward and causes other structural defects there. When the heating furnace 1 is moved there, the structural defects are removed and the silica glass fiber becomes transparent. By repeating these steps, the fiber is processed throughout length. Thus, mass production becomes possible and an improvement of productivity and lower costs can be achieved.

Abstract: A processing method of a silica glass fiber, which is applicable to a long fiber, to improve its UV resistance by UV irradiation and heat treatment. Initially, a heating furnace 1 is positioned such that the left end of the silica glass fiber is within the heating furnace 1. Then, the heating furnace 1 is moved toward the right, while UV is irradiated with a UV source to the left end surface of the silica glass fiber. Since the silica glass becomes transparent due to removal of structural defects that have been caused by the UV irradiation, the UV travels further forward and causes other structural defects there. When the heating furnace 1 is moved there, the structural defects are removed and the silica glass fiber becomes transparent. By repeating these steps, the fiber is processed throughout length. Thus, mass production becomes possible and an improvement of productivity and lower costs can be achieved.

Abstract: A method of manufacturing an optical fiber using silica glass having properties changed by UV irradiation and heat treatment, which method facilitating efficient mass production of long optical fibers. A base material of silica glass is heated in a fiber spinning heating furnace, and a silica glass fiber is drawn out of the forward end of the heating furnace to be spun up. In a UV irradiation zone, UV is irradiated to the spun silica glass fiber. As a result, multiple structural defects are caused in the silica glass fiber. When the structural defects are removed by heat treatment, the average bond angle of Si—O—Si network in the silica glass increases compared with that before heat treatment, and structural relaxation proceeds to provide a structurally stable glass, in which generation of defects due to further UV irradiation is hindered. Thus, a silica glass fiber having high UV resistance is obtained.