| 摘要 |
PURPOSE:To prepare an optical fiber of low loss, by forming a high-purity barrier layer on the inner surface of a glass tube and a high-purity core glassy layer on the inner surface thereof at a specific temperature respectively, heating the glass tube, and drawing the resultant solid tube. CONSTITUTION:A quartz glass tube 1 is mounted on a glass lathe 4, and a raw material gas for glass at a molar ratio of SiCl4:POCl3:BCl3=93:5:2 is fed into the tube 1, using O2 gas as a carrier gas. A barrier layer 2 of P2O5-B2O3-SiO2 glass having almost the same refractive index as the tube 1 is formed in a temperature range of 1,350-1,450 deg.C, with the movement of a burner 5. A core glassy film 3 of GeO2-P2O5-SiO2 glass is further formed on the inner surface of the barrier layer 2. The tube 1 in the conditions thus obtained is then heated, made solid and drawn to give the aimed fiber of low loss. GeO2-P2O5-B2O3-SiO2 glass or the like may be used as the material of the barrier layer 2. |
