| 摘要 |
PURPOSE:To obtain the title preform capable of being enlarged and capable of efficiently producing an optical fiber by providing a hole whose center axis is aligned with a self-graded index optical fiber preform, inserting a single-mode optical fiber into the hole, drawing, and integrating the material. CONSTITUTION:A self-graded index optical fiber preform and a single-mode optical fiber preform are firstly produced by VAD. The preforms are vitrified in a heating furnace to obtain a self-focusing optical fiber preform 1 and a single-mode optical fiber preform 2. A hole 3 is then provided on the center axis of the self-graded index optical fiber preform 1 having a parabolic refractive index distribution so that both center axes are aligned, the single-mode optical fiber preform 2 with the surface polished by etching, etc., is inserted into the hole 3, and both preforms 1 and 2 as such are drawn and integrated by the rod-in-tube method, etc. Since the size of the hole 3 is determined and designed in accordance with the characteristics of the desired optical fiber, the size is variously changed in accordance with the characteristics to be obtained. The preform is spun, and a dispersion flat-type optical fiber can be obtained. |
