| abstract |
(57) [Problem] To provide a high-efficiency optical fiber and amplifier suitable for amplification in a 1.3 μm band. 8. An optical amplifier, quartz glass doped with Bi [xBi 2 O 3 -yAl 2 O 3 - (1-x- y) SiO 2] is, Bi 2 O 3 in mole percent from 0.1 1 0.0%, Al 2 O 3 is 2 to 20%, and x <y It is 1.3 μm when excited by a 0.8 μm band semiconductor laser. An optical fiber for amplifying m-band signal light is used. |