MULTIWAVELENGTH PROPAGATION IN LIGHTWAVE SYSTEMS WITH STRONGLY INVERTED FIBER AMPLIFIERS

Unlike single-channel systems, which favor saturated operation, multiw avelength erbium-doped fiber amplifier cascades offer substantial perf ormance advantages when operated with minimal saturation at very stron g inversion levels. This is due to ground-state absorption which, in p artially inverted amplifiers, yields strong wavelength-dependent atten uation and thus large inter-channel power spread. In a strongly invert ed six-amplifier chain, the inter-channel power spread per amplifier i s suppressed by about an order of magnitude compared with the same sys tem operated well into gain-compression.