Comparison of Advance Data Modulation Formats in 4×10Gbps WDM Optical Communication System using YDFA, EDFA and Raman Amplifier

In this paper, comparison of various advance data modulation formats in 4×10Gbps wavelength division multiplexing (WDM) optical communication system using YDFA (ytterbium doped fiber amplifier), EDFA (erbium doped fiber amplifier) and Raman amplifier has been carried out. The advance modulation formats under investigation include NRZ (non return to zero), RZ (return to zero), CSRZ (carrier-suppressed return to zero), DRZ (duobinary return to zero) and MDRZ (modified duobinary return to zero).The WDM system has been analyzed for 10Gbps over 100km fiber. It has been observed that MDRZ transmitter gives superior results followed by DRZ and CSRZ also RZ performs better than NRZ. On comparing amplifiers, YDFA and EDFA show comparable results. MDRZ performs better than DRZ and CSRZ in both the amplifiers. In Raman amplifier CSRZ outperform DRZ but both are inferior to MDRZ. The best results have been reported for EDFA with MDRZ modulation format, where the maximum Q factor of 18.57dB is achieved. The performance degradation over a fiber in optical system is due to nonlinearities. MDRZ show high immunity towards nonlinearity. It is determined that MDRZ format seems to be best choice for the transmission distance beyond 100km.