| 摘要 |
PURPOSE:To make it possible to produce the titled optical fiber exhibiting longitudinally stabilized transmitting performance and dispersing performance, by deciding a drawing diameter of a core rod according to a specific equation, when the core rod is drawn to a prescribed outside diameter, inserted into a quartz tube and simultaneously drawn. CONSTITUTION:A part to be drawn of a core rod consisting of a core part and clad part provided as surrounded by the core part is measured in a radius direction every prescribed length by a preform analyser to seek a distribution of refractive index. An equivalent core radius ae[mm] of ESI distribution is calculated from the distribution by the prescribed equation. Further, a refractive index n1e and difference of relative refractive index DELTAe[%] of equivalent core is sought by the prescribed equation. A drawing diameter de[mm] of the core rod is calculated using those each value by formula I and II, wherein S is a cross section [mm<2>] of jacket quartz tube, D is an outside diameter [mm] of the core rod, lambdac is a design value [mum] of cut off wavelength and (a) is an outside diameter [mum] of drawn optical fiber. |
