| 摘要 |
PURPOSE:To obtain an optical fiber propagating infrared rays of long wave length having neither toxicity nor deliquescence, by specifying the composition of fluoride glass, by making glass preparation of quenching to <= crystallization temperature possible. CONSTITUTION:An optical fiber comprising a fluoride consisting of 5-32mol% CaF2, 11-32mol% BaF2, 2-29mol% YF3, and 31-51mol% as AlF3 as a basic parent material. In the preparation, in the first place, NH4F.HF and NH4Cl as a treatment is added to a raw material for mixed powder of the desired composition, and the blend is heat- treated in an inert gas atmosphere in a temperature range from 100 deg.C to <= the melting point of the raw material for >=20min. All the treatment is completely evaporated, the oxide impurity and water in the raw material are removed during the treatment, and the absorption loss of the optical fiber and the absorption loss by OH are reduced. The raw material is then heated at >= its melting point and melted, passed through the platinum nozzle 2, introduced to the hollow cylindrical container 5 rotating at a speed of >=5rpm. kept at a temperature <= the crystallization temperature of the raw material, and quenched. When the rotation speed of the container 5 is low, bubbles remain, the prepared glass parent material becomes white, and crystallization occurs. |
