Hybrid fiber amplifier

摘要

The present invention relates to a multi-wavelength multi-stage fiber amplifier exhibiting high power output with a flat balanced gain spectrum. The input stage (22) exhibits a given passive loss and a flattened gain spectrum. The output stage (23) exhibits a passive loss that is lower than the given passive loss and a gain spectrum that is less flat than the gain spectrum of the input stage. In a system utilizing erbium-based gain fibers, the input stage gain fiber can contain an amount of alumina sufficient to provide the desired gain spectrum flatness, while the output stage gain fiber has an alumina concentration sufficiently low to render that stage essentially lossless. <IMAGE>