| 摘要 |
PURPOSE:To obtain an inexpensive and high-quality optical fiber preform having low loss and high accuracy, by forming a specific quartz glass (SG) tube and making a glass layer having a higher refractive index than the SG tube in the inner wall of the SG tube. CONSTITUTION:A solution obtained by hydrolyzing an alkyl silicate is blended with silica fine particles to give a sol solution, which is gelatinized to give a tubular wet gel. Then the tubular wet gel is dried and sintered to give a tubular porous material, to which a fluorine is added in a fluorine-containing gas atmosphere and the tubular porous material is made transparent to give a fluorine-containing SG tube. Then the SG tube is cleaned by making O2 flow in the tube while heating the inner wall of the SG tube, SiCl4 and O2, etc., are made to flow in the tube to form a pure silica glass layer having about 36mum thickness and high refractive index on the inner wall of the SG tube and the tube is collapsed to give an optical fiber preform. |
