Nature or refinement manner of the synthetic silica, and, the nature which was refined or the mannered null heat energy grant means which make the synthetic silica precipitate with respect to

摘要

PROBLEM TO BE SOLVED: To improve the qualities of an optical fiber recharged with a natural or synthetic silica at a low cost. ;SOLUTION: The deposition of a natural or synthetic silica involves a preform 1 rotating in front of a plasma torch 3 and a supply tube 9 for supplying a natural or synthetic silica particle 11 to a plasma. The supply tube 9 supplies a fluorine or chlorine compound, preferably the fluorine compound mixed with a carrier gas 15 to the plasma. The plasma torch 3 is reciprocated approximately in parallel with the longer direction L of the preform 1. An alkali or alkaline earth metal element contained in the natural or synthetic silica particle is reacted with fluorine or chlorine in the fluorine or chlorine compound.;COPYRIGHT: (C)2000,JPO