| 摘要 |
PURPOSE:To obtain the title preform capable of providing an optical fiber having excellent resistance to hydrogen and radiation, stability, and reliability by inserting a core rod into a clad pipe, fusing and integrating both materials while allowing a reducing gas to flow in the gap between them so as to eliminate a peroxy bonding at the interface. CONSTITUTION:The core rod 1 consisting of pure quartz glass, etc., is inserted into the clad pipe 2 consisting of F-added quartz glass, etc., 0.5-50vol.% reducing gas such as D2 and CO, based on the total gas amt., an inert gas such as N2, Ar, and He, and a dehydrating agent such as Cl2 and SOCl2, if necessary, are supplied in the gap between both materials at a rate of 10-500cc/min (however the content of D2 is controlled to 0.5-4.0vol.% to prevent explosion when Cl2 is added as the dehydrating agent), the periphery of the pipe 2 is simultaneously heated by an H2/O2 burner 3, and both materials 1 and 2 are fused together at 1300-1800 deg.C collapsing temp. |
