OPTICAL AMPLIFIER

摘要

In an optical amplifier for amplifying a signal light by propagating the signal light and a pumping light in a rare earth element doped fiber (2) doped with a rare earth element, a diameter of a rare earth element doped portion of the rare earth element doped fiber (2) is gradually reduced in a direction of propagation of the pumping light. With this construction, an adverse rare earth element doped area which does not contribute to optical amplification but rather attenuates the pumping light can be eliminated to thereby provide an optical amplifier suitable for an increase in amplification efficiency.