Abstract

Erbium-doped fiber amplifiers (EDFA's) have revolutionized both long-distance and distribution-based optical communication systems. Adequate signal-to-noise ratios (SNR) have already been demonstrated for both single-channel [1] and two-wavelength-channel [2] multi-megameter transmission systems as well as for wavelength-division-multiplexed (WDM) distribution systems.[3-5] However, transmitting many WDM amplified channels is difficult to implement since the EDFA gain as a function of wavelength is not uniform whereas the link loss (due to propagation attenuation or optical splitting) is independent of wavelength. Such a gain/loss wavelength discrepancy will result in a signal-power and SNR differential between channels after passing through only one amplifier for either long-distance or distribution systems. As a result of passing through a cascade of EDFA's, this discrepancy is compounded.

© 1993 Optical Society of America