| 摘要 |
PURPOSE:To provide the optical fiber which has sufficient heat resistance and decreased transmission losses to near IR light by using specific polyimide as the main constituting elements of the core and clad of the optical fiber. CONSTITUTION:The core or clad or both of the optical fiber consist of the polyimide having the repeating unit expressed by formula I, a polyimide copolymer or a polyimide mixture as the main constituting elements. In the formula I, R1 denotes the group expressed by formula II, etc.; R2 denotes the group expressed by formula III, etc. In the formulas II and III, R1 denotes fluorine, perfluoroalkyl group. Namely, the vibration absorption based on the C-H bonds which is the max. light loss in the near IR region is eliminated by using univalent elements exclusive of hydrogen for all of the univalent elements to be bonded to the carbon in the polyimide and more particularly, using fluorine as the univalent element. The heat resistance is thereby provided on the optical fiber and the absorption peak in the near IR region is no longer observed. |
