FIBEROPTIC FOR AMPLIFIER OF LIGHT

An optical fiber for use in a light amplifier. The optical fiber is formed by doping a gerrnanium-gallium-sulfur (Ge-Ga-S) glass containing less sulfur than a GeS2-Ga2S3 stoichiometric composition line with a rare earth element, and further contains 0.1~10 atomic % of a halogen element base on the Ge-Ga-S glass. By using optical fiber, clustering of praseodymium (Pr+3) ions can be suppressed even when the concentration of added Pr+3 is high, thereby improving light amplification efficiency.