| 摘要 |
PURPOSE:To obviate remaining of internal stress at the time of forming a fiber and to obtain the low-loss fiber by providing 1st and 2nd clads which are successively increased in softening temp. to the outer side of a core essentially consisting of quartz glass. CONSTITUTION:A quartz glass rod 1 for the core doped with germanium is rotated at 40rpm and prescribed amts. of SiCl4 and Ar, H2, O2 are supplied by a quadruple-tube burner 2 to deposit a fine SiO2 glass particle layer 4 on the rod by a flame 3. This layer is vitrified to transparent glass in an atmo sphere furnace kept at the max. high temp. of 1,620 deg.C to form the 1st clad higher in the softening temp. than the core. The SiO2 glass articles are again deposited thereon and are put into a quartz muffle tube 5. The conditions are slightly changed and the 2nd clad having the higher softening temp. than the softening temp. of the 1st clad is formed. Remaining of the stress in the fiber is obviated if this rod is drawn to make the fiber. |
