Method and system to estimate SRS induced gain change in optical communication networks

An optical communication system comprising:

• a first wavelength division multiplexer (WDM) configured to receive WDM signals in C+L bands, the first WDM is further configured to split the received WDM signals into C band WDM signals and L band WDM signals;
• a C band amplifier configured to amplify the C band WDM signals and compute a first total instantaneous power associated with the C band WDM signals on a first time scale;
• an L band amplifier configured to amplify the L band WDM signals and compute a second total instantaneous power associated with the L band WDM signals on the first time scale;
• a slow per channel power detector configured to extract slow per channel powers associated with the WDM signals on a second time scale;
• a Stimulated Raman Scattering (SRS) estimator configured to estimate an SRS induced gain change in the WDM signals using the first total instantaneous power, the second total instantaneous power, and the slow per channel powers corresponding to n wavelengths in the WDM signals, wherein n is an integer;
• and
• a second WDM configured to combine and transmit the amplified C band WDM signals and L band WDM signals over optical cables.