Signal light amplification by stimulated Raman scattering in an N-channel WDM optical fiber communication system

The use of forward and backward Raman amplification in an N-channel wavelength-division-multiplexing (WDM) optical-fiber communication system is analyzed. Analytical expressions for the signals, the pumps, and the amplified spontaneous scattered power (ASSP) are presented. The crosstalk among the signal channels is analyzed in terms of system parameters. It is found that the crosstalk is negligible while low pump power is used and becomes significant if high pump power is used. The signal-to-ASSP ratio can be improved by increasing pump power; however, the improvement is small when pump power is already high. A 300-km repeater spacing with more than 20-dB signal-to-ASSP ratio is calculated.<
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