| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical fiber which decreases reflected light within a prescribed limit by including a doped core and a doped end which encloses this doped core and absorbs the light radiated from the doped core. SOLUTION: This optical fiber includes the doped core and the doped end which encloses this doped core and absorbs the light radiated from the doped core. For example, the fiber 21 consists of a signal transmission section 30 and a signal attenuation section 50. The core 22 acts in such a manner that the light passes the inside of the fiber 21. At this time, the very small part of the light passing the core 22 leaks out of the circumference of the core 22. The absorption of the light is preferably higher in rate as the quantity of the light leaking from the region of the core 22 is higher. About 4% of the light in the small quantity of the light leaking from a high-absorption region is reflected at the boundary and returns to the fiber 21. The reflected light returns to the same high-absorption region. Such absorption is embodied by doping a material which absorbs the wavelength light released by the core 22 region to the region adjacent to the core 22. |
