Comparative analysis of an 80 Gbps radio over fiber system using Duobinary PAM and NRZ Modulation

Duobinary signal is a sort of advanced electrical modulation that prevents bandwidth limitations of optical fiber signal, through which high data capacity of transmission is achieved. This paper demonstrated a comparison between different formats of duobinary modulations: a duobinary NRZ, duobinary PAM, and a conventional nonreturn-to-zero Mach–Zehnder modulator (NRZ MZM) in an 8 WDM radio over optical fiber communication. Optisystem 22 is optimized to design and run THE system adapted to transmit 8 × 10 Gbps. Based on the performance indicators, the duobinary signal demonstrated a performance higher to the conventional NRZ MZM, as well as a longer fiber transmission length up to 400 km with a minimum Q-factor of 6. The NRZ MZM scheme allows maximum range of about 200 km to maintain the Q-factor at the threshold. The duobinary PAM with dispersion compensation factor DCF signal provided a Q-factor performance of round 6 higher up to the distance of 350 km, compared to the duobinary NRZ–DCF. However, a duobinary PAM–FBG dispersion compensator shows significant reduced BER and enhanced Q-factor at short lengths, it suffers a rapid degradation with increasing the length. Meanwhile, the duobinary NRZ and PAM-based DCF sustain stable performance declination with fiber length indicating the robustness against channel distortions.