| 摘要 |
PURPOSE:To readily obtain a preform for optical fiber having the aimed refractive index distribution, by adding a Si compound to O2 gas to be fed especially to the outermost nozzle of a concentric multiple pipe and by depositing formed silica fine powder and dopant fine powder on a bar carrier. CONSTITUTION:SiCl4 and GeCl4 as a dopant are fed to a central nozzle 1 of quadruplex burner 4 made of quartz, H2 gas to a nozzle 2, Ar gas to a nozzle 3 and O2 gas and SiCl4 to a nozzle 4. The oxyhydrogen flame burner is ignited. Consequently generated silica powder is deposited on a carrier bar made of quartz at a given deposition rate and the carrier bar is transferred in the longitudinal direction at a give speed to prepare a porous core preform. Then the core preform is sintered and transparentized in a furnace heated to 1,500 deg.C to give an optical fiber preform. The refractive index distribution of the preform is grated index type, smooth and no irregularity is observed. |
