Patent ID: 6771415
Filing Date: 2004-08-03
Classification: H01S

Abstract:
An optical fiber for optical amplification used for 1.58 &mgr;m band signal light amplification, at least a core region thereof being doped with Er;wherein at least part of said core region is made of silica glass co-doped with only Al and Er, the Al atomic concentration in said core region is from 5 wt % to 20 wt % inclusive, the Er average atomic concentration in said core region is from 1000 wt- ppm to 3000 wt-ppm inclusive, the cutoff wavelength is from 1.3 &mgr;m to 1.5 &mgr;m inclusive, and a mode field diameter in the 1.58 &mgr;m band of said optical fiber is 5 &mgr;m or more.