L-BAND AMPLIFIER WITH DISTRIBUTED FILTERING

摘要

An L-band optical amplifier has a rare earth doped gain medium including a filter distributed over a finite physical portion of the gain medium. The filter is distributed over between about 25 % to substantially the entire length of the gain medium. The distributed filter substantially eliminates out-of-band light emission (C-band ASE, 1520nm-1565nm) and thus improves the performance of L-band amplification (1565nm-1620nm). Examples of distributed filters include discrete type filters such as long period gratings, or continuous type filters such as rare earth doped, twin core fibers, non-adiabatically tapered fibers and coaxial resonant ring fibers.