| 摘要 |
PURPOSE:To mass-produce the title material with little light loss by making the inside diameter of a support glass tube sufficiently larger than the diameter fo rodlike glass for a core and using an internal heating method applying plasma discharge in an improved version rod-in-tube method. CONSTITUTION:Rodlike glass 1 for a core is set at the center of support glass tube 2 having an inside diameter sufficiently larger than the diameter of glass 1, and vapor phase raw material such as silicon cpd. 4 which can be oxidized at high temp. and mixed gas 5 of oxygen gas, gas of halide of a doping element and inert gas such as argon are introduced into the space between glass 1 and tube 2. High frequency power is then applied through coil 3 to generate plasma discharge in tube 2. By this discharge the internal temp. of tube 2 becomes higher (about 1200- 2000 deg.C) than the temp. of the tube wall, whereby the introduced silicon cpd. is oxidized, deposited as doped quartz glass of a low refractive index on the surface of glass 1, and fusion-bonded. Glass 1 is then spun to obtain a base material for light transmission. |
