| 摘要 |
PROBLEM TO BE SOLVED: To obtain a flat gain, by doping an optical fiber with a co-dopant, and by radiating a wavelength that corresponds to an energy level transition of the co-dopant and is outside a forbidden band of erbium energy level transitions. SOLUTION: Concerning the doping or co-doping characteristics, a preferable percentage content of erbium and ytterbium ranges from 500 ppm (parts per million) to 15,000 ppm. Further, their preferable ratio is 30 to 1. The amount of ytterbium may range from 10,000 ppm to 50,000 ppm. A preferable pump wavelength is 1064 nm. The energy level is continuous or quasi-continuous above the S3/2 level. Therefore, the excitation wavelength should be outside a wavelength corresponding to energy bands of transition of an erbium atom from its I11/2 level to its S3/2 level or higher. |
