| 摘要 |
PURPOSE:To enable stable prepn. of optical fiber with small loss and high numerical aperture by prepg. optical fiber without interposing a stage for allowing a preform comprising core and clad to stand at ordinary temp. CONSTITUTION:A layer of glass having the same or smaller refractive index than quartz and larger coefft. of thermal expansion than quartz is laminated on the inside surface of a quartz pipe, and further a layer of glass having larger refractive index than quartz is laminated thereon. The pipe is then heated to make the pipe to a solid body, further, the glass rod obtd. by this treatment is polished by flame polishing successively to remove the quartz. Obtd. round rod 1 and a quartz pipe 2 are arranged concentrically by holding with holding tools 3, 4, and both are drawn by heating in a heating furnace 5 to form one body and optical fiber is prepd. simultaneously. Since, by this process, optical fiber is obtd. without a stage for holding a preform comprising different kind of glass having large difference in the coefft. of thermal expansion at ordinary temp.; optical fiber having high numerical aperture is obtd. practically, and, since the core glass and the interlayer glass are prepd. by the CVD process, the purity of obtd. optical fiber is elevated and the boundary region of the intermediate layer is uniform, and its light transmitting loss is small. |
