| 摘要 |
PURPOSE:To obtain the optical fiber base material and optical fiber changed in the conc. of a rare earth element in a radial direction by repeating stages consisting in immersing a porous glass base material into an alcohol soln. of a rare earth element chloride, drying this base material and vitrifying the material to transparent glass. CONSTITUTION:The porous glass base material 1 having about 30mm diameter is produced by a VAD method on a quarts target rod 3. This base material is immersed into the alcohol soln. 5 of, for example, 0.05 wt.% ErCl3 for about 2 hours. After the base material is dried in the atm., the base material is put into an electric furnace 6 and is sintered at about 1620 deg.C to form the transparent glass. The glass is elongated to about 15mm diameter and the porous glass is deposited thereon by an external deposition method. The material is then immersed into the alcohol soln. of the ErCl3 of the lower concn. than before and is similarly vitrified to the transparent glass. The conc. of the ErCl3 is successively lowered and this stage is repeated about 5 times. |
