OPTICAL FIBER FOR AMPLIFICATION, OPTICAL FIBER AMPLIFIER, OPTICAL TRANSMITTER, AND OPTICAL COMMUNICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an optical fiber for amplification and the like which requires no gain equalizer with a flat gain spectrum and excellent polarization quenching ratio. SOLUTION: An optical fiber (10) for amplification comprises a core region (11) in the light propagation region in which the signals of different wavelengths propagate, a clad region (12) provided around the core region (11), and a polarized wave holding structures (13a and 13b) which hold the polarized state of the signal. The optical fiber (10) for amplification comprises a quarts glass as a main component, and Er element as well as Al element at 4 wt.% or higher is added to at least a part of the light propagation region containing the core region (11).