Investigation on Nyquist-WDM Channels with Optical Sinc-shaped Pulses Based on Electro-Optic Frequency Combs

The practicability of Nyquist wavelength-division-multiplexed (WDM) channels with optical Sinc-shaped pulses is greatly limited by phase noise and power flatness of the WDM sources. We insert uniform and coherent lines around each line of flat electro-optic frequency combs to generate 5 Nyquist-WDM channels with high quality. The normalized root-mean-square error (NRMSE) of optical Sinc-shaped pulses for the 5 channels can be between 1.23%–1.96%. The optical signal-to-noise ratios (OSNRs) of optical Nyquist pulses have a 7 dB improvement by reducing optical linewidth of electro-optic combs. Further, the high OSNR of Nyquist-WDM channels can bring benefits to transmission performance in high spectral efficiency Nyquist-WDM communication system.