| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a preform for an optical fiber, which manufactures the preform for an optical fiber having optical fiber characteristics strong to bending, at low cost. <P>SOLUTION: The method for manufacturing the preform for the optical fiber is configured such that: a soot deposit having a high-refractive index part at the center is manufactured by VAD method or OVD method; the soot deposit is dehydrated at such a temperature that the soot deposit is not vitrified in a helium atmosphere added with chlorine; then, the soot deposit is vitrified in a helium atmosphere at a vitrification temperature to make a core rod; and a clad is further imparted to the outside of the core rod by OVD method, RIT method or the like, wherein the helium atmosphere in a heating furnace when the soot deposit is vitrified contains a fluorine compound gas, and the concentration of fluorine in the atmosphere gas is in the range of 0.1 to 10%. <P>COPYRIGHT: (C)2013,JPO&INPIT |
