Performance comparison of wavelength shift keying WDM system and conventional on-off WDM system in presence of four-wave mixing

Performance of wavelength shift keying (WSK) wavelength division multiplexed (WDM) system is analyzed and compared to that of conventional on-off keying (OOK) WDM system in respect of four-wave mixing (FWM) effect. WSK technique employs symmetric wavelength assignment and balanced detection to cancel FWM interference to first order. WSK-WDM outperforms conventional OOK-WDM at all signal levels and permits higher allowable input power, lower power penalty and higher transmission distance for a given bit-error rate of 10−9. WSK-WDM is also found to be noise resistant.