Low SNR difference Nyquist-WDM channels with optical sinc-shaped pulses based on flat electro-optic frequency combs

Area of Science:

• Optoelectronics
• Optical Communications
• Signal Processing

Background:

• Nyquist wavelength-division-multiplexing (WDM) is crucial for high-capacity optical communication.
• Interchannel crosstalk and signal-to-noise ratio (SNR) differences are significant challenges in WDM systems.
• Electro-optic combs (EOCs) offer potential for generating stable WDM channels.

Purpose of the Study:

• To experimentally demonstrate Nyquist-WDM channels with a low SNR difference using flat EOCs.
• To reduce interchannel crosstalk penalty in Nyquist-WDM transmission without guard bands.
• To improve the overall communication performance of WDM systems.

Main Methods:

• Generation of five Nyquist-WDM channels using uniform and coherent lines from flat EOCs derived from a dual-parallel Mach-Zehnder modulator.
• Characterization of optical sinc-shaped pulses with a repetition rate of 9 GHz, showing normalized root-mean-square errors between 1.23% and 2.04%.
• Transmission performance evaluation of the five Nyquist-WDM channels over a 56 km fiber link.

Main Results:

• Achieved SNRs better than 30 dB for Nyquist signals using flat EOCs with narrow linewidth.
• Demonstrated a low SNR difference of less than 0.6 dB among the WDM channels.
• Observed a minimum interchannel sensitivity penalty of 0.7 dB at the forward-error-correction limit.

Conclusions:

• Flat EOCs effectively generate Nyquist-WDM channels with low SNR differences.
• The proposed scheme significantly reduces interchannel crosstalk penalty in Nyquist-WDM systems.
• Low SNR difference in Nyquist-WDM channels enhances overall communication system performance.