| 摘要 |
PURPOSE:To obtain the title matrix capable of efficiently producing optical fibers of low dispersion over a broad wavelength range excellent in transmission loss characteristics, by preparing, separately, a core, first clad and second clad and by integrating to the core the first clad followed by the second clad into unity according to a prescribed design. CONSTITUTION:Firstly, a core, first clad and second clad are separately prepared, in advance, using the respective specified raw materials, by making a suit through the VAD technique followed by making said suit transparent. Secondary, the core glass material is inserted into the first clad glass material having refractive index lower than that of said core glass material followed by heat fusion to obtain a glass rod. Secondary, the outer peripheral portion is cut and removed so that the ratio of the core diameter to the first clad outer diameter fall within a specified range. Thence, the resulting unit is inserted into a cylindrical second clad glass material with its refractive index lower than that of the core but higher than that of the first clad, followed by heat fusion into unity. Finally, the outer peripheral portion is cut and removed so that the ratio of the second clad outer diameter to the first clad outer diameter fall between 3 and 6, thus obtaining the objective matrix having W- shaped reference index distribution with low dispersion in the light transmission wavelength range and wavelength dispersion of 0 at least two wavelengths. |
