Hybrid MDRZ–BPSK optical modulation technique for improved spectral efficiency in WDM optical communication systems

In this work, the design and evaluation of a hybrid optical modulation technique for wavelength division multiplexing (WDM) technology is presented. The proposed optical system consists of 21 channels, with each channel generating a data rate of 45 Gbps, using advanced modulation techniques such as binary phase shift keying (BPSK) and modified duobinary return-to-zero (MDRZ). The performance of the hybrid modulation format is evaluated at a channel spacing of 100 GHz. The key performance parameters, including spectral efficiency, signal quality, optical signal-to-noise ratio (OSNR), eye opening factor (EOF) spectral efficiency, receiver sensitivity, and BER (bit error rate), are investigated using the proposed hybrid optical modulation technique. The results demonstrate that employing MDRZ with BPSK can improve the performance of the WDM system, making it suitable for noise-resistant and long-haul optical communication systems. The highest values of OSNR, signal quality, and spectral efficiency achieved are 49.6 dB, 47.77, and 11.157 bit/s/Hz, respectively. The obtained results indicate enhanced WDM system performance, which can further be utilized in high-data-rate communication systems.