Optical fiber for optical amplification and optical fiber amplifier

摘要

An optical fiber (1) for optical amplification used for 1.58 mu m band signal light amplification, at least a core region (11) thereof being doped with Er, wherein at least a part of the core region (11) is made of silica glass co-doped with Ge and Al together with Er, an average Er atomic concentration in the core region (11) is from 950 wt-ppm to 3000 wt-ppm inclusive, and a mode field diameter in the 1.58 mu m band is 5 mu m or more.