Performance Evaluation of 64x20 Gb/s DWDM Optical System using Raman-EDFA for Different Channel Spacing

In this paper hybrid optical amplifier is investigated by cascading configuration of distributed fiber Raman amplifier and Erbium doped fiber amplifier for 64 X 20 Gb/s dense wavelength division multiplexing operating at different channel spacing (25, 50, 100, 150 GHz). At the input power of -10 dBm and variation in the Raman fiber length (20 to 100 km) of Raman amplifier, the on-off gain of more than 34 dB up to 40 km of Raman fiber length at 100 GHz channel spacing. The noise figure is 8 to 11 dB and is minimum up to 40 km and output signal is also maintained at this Raman fiber length. When the input power is varied from -10 dBm to 4 dBm at 40 km of Raman fiber length the on-off gain is 35.7 dB and it is slightly decrease with increase of input power and noise figure is maintained less than 12 dB at 100 GHz channel spacing. From the investigations 40 km is found to be the optimum Raman fiber length, and among different channel spacing 100 GHz may be a better choice for obtaining better gain and noise figure results.