Optical amplification fiber, fiber optic amplifier, and optical communication system

摘要

This invention relates to an optical amplification fiber having a structure capable of exhibiting an excellent amplification characteristics, and the like. In the optical amplification fiber, the ratio (alphaP/alphaS) of an unsaturated absorption peak value alphaP in a pumping light wavelength band of 0.98 mum to an unsaturated absorption peak value as in a signal wavelength band of 1.55 mum is 0.8 or more and, more preferably, 0.9 or more.