Method and apparatus for optical system link control

Fiber optic communications systems continue to grow dramatically in terms of numbers, capacity, and complexity. One of the factors responsible for this trend is the increasing sophistication of optical amplifiers, particularly erbium doped fiber amplifiers (EDFA's). Furthermore, the technology driving EDFA's is expanding the spectral bandwidth in which such an amplifier can amplify input signals so that scores of channels with sub-nanometer spacing can be amplified and transmitted in current systems. Other network optical elements such as DWDM's, WADM's, optical cross-connects, etc., which are compatible for use in communications systems employing 80+channel amplifiers are also now available. A method for tuning and improving the performance of an optical communication system comprising al link that includes optical amplifiers and, optionally, active and/or passive optical components such as, e.g., DWDM's, WADM's, and optical cross-connects, includes preferentially shaping and, in particular, flattening, with respect to the input power spectrum, the output power spectrum from the amplifier, component or of the link. A flattened output power spectrum is obtained by modifying the gain spectrum operating on the respective input power spectrum. Feedback for such gain modification is typically provided by optimizing the optical signal to noise ratio of each channel of the respective output power spectrum. A system link, an optical amplifier, and optical components having flattened output power spectra are also described.