HIGH-EFFICIENCY ERBIUM-DOPED FIBERS AND HIGH-PERFORMANCE OPTICAL-COMPONENTS FOR OPTICAL-FIBER AMPLIFIERS

By optimizing the structure of erbium-doped fibers, high efficiency su ch as a gain coefficient of 6.3 dB/mW, or a slope efficiency of 92.6% have been realized with very flat wavelength dependence. Though the op timized structure has high NA, the splice loss with standard fibers ca n be lowered by the additional arc technique. The carbon coated fiber with a fatigue parameter over 150 guarantees the reliability, even whe n wounded on a small coil. In-line isolators and WDM couplers have bee n also developed. An amplifier module has been assembled, resulting in an output power more than + 16 dBm owing to the high performance of e ach component.