Suppression of Four Wave Mixing Effects Under Different Spectrally Efficient Modulation Techniques in Hybrid DWDM-OTDM Systems

Next generation optical networks require high spectral efficiency to meet the demand of high bandwidth for ultra-long haul communication. Spectrally efficient modulations using hybrid DWDM-OTDM systems can be used to achieve this. However, fiber nonlinearities such as four-wave mixing (FWM) will increase simultaneously and this will degrade the performance of WDM optical system. This paper explores the FWM reduction in 32 channels, 40 Gb/s hybrid DWDM-OTDM network using RZ-OOK, 16-QAM and PDM-QPSK modulation format at 200 GHz and 100 GHz channel spacing. Optical received power, BER, Q- factor, eye diagram and FWM side band power are analyzed at -15dBm to +15dBm channel power. All these modulations have shown a significant reduction in FWM. In addition, the 16-QAM gives highest reduction in FWM along with least BER of 7.9×10⁻¹⁵⁸ and maximum Q-value of 27.74.