US Patent 7587139 Optical channel power control in WDM networks

Information about optical amplifier ASE power is propagated down a link. Each amplifier along the link can learn of the ASE power at its input and take this input ASE power into account in controlling its own per channel output power. Each amplifier can also pass along to the next amplifier an indicator that represents its output ASE power taking into account both its input ASE power and own generated ASE power. Intermediate optical add/drop multiplexers (OADMs) adjust the ASE power indicator to account for losses and the spectral characteristics of each filter.