Patent ID: 6323993
Filing Date: 2001-11-27
Classification: H04B

Abstract:
A method for operating a DWDM communication system comprising a plurality of optical fiber spans separated by repeater units, wherein: each repeater unit injects an optical signal having plural wavelength channels into the span that follows it at a respective injected signal power level; the system has a design requirement that a target signal-to-noise ratio (SNR) must be met or exceeded at the end of each span; and the system is subject to non-linear optical effects leading to errors in interpretation of the received signal that are related to signal statistics by a quality factor Q such that higher Q is associated with lower bit error rate (BER); the method comprising:injecting the optical signal into at least one span at an injected power level that falls short by a shortfall .DELTA.P of the power needed to reach the target SNR at the end of that span, wherein .DELTA.P is selected to raise Q in every channel by at least 2 dB; andcompensating for said shortfall by applying remotely pumped, distributed amplification to the optical signal within said at least one span.