Comparison of RZ and NRZ Modulation Techniques by Varying Duty Cycle and Mach Zehnder Modulator

The aim of the research being undertaken is to examine the performance of advanced modulation formats such as RD and NRZ modulation schemes and their long-haul repeater-free fibre-traffic (SMF). Modular transmission of signals by SMF has been highly attracted by several benefits, such as high chromatic dispersion tolerance (CD), simplicity of deployment and higher spectrum efficiencies. These are the essential performance indicators of an optimal modulation technique for the creation of multiplexed (DWDM) transmission networks of the future generation of dense wavelengths. Based on a comparison of the two modulation approaches I give my findings. To mimic both modulation schemes, OptiSystem software is employed. Eye diagram with measurement of the Q factor and BER is generated. Keywords: Return to Zero, Non-Return to Zero, Eye Diagram, Bandwidth, BER, Q factor.

Simulation of WDM-ROF-PON selective access link system based on hybrid modulation of MZM and OFM

Based on the introduction of the principle of the optical wireless system, the WDM-ROF based on hybrid modulation of MZM and OFM is designed WDM-ROF-PON system architecture, using simulation software to build the system to verify the rationality of the MZM and OFM hybrid modulation system structure; and put forward an MZM and OFM hybrid modulation scheme, using IRZ code in the downlink data stream, with better extinction ratio and dispersion tolerance, reducing the cost of the user receiving equipment, improving the system transmission quality. The simulation results show that the scheme of MZM and OFM hybrid modulation WDM-of-pon network architecture is reasonable and practical.

Novel Manchester-Based Multilevel Signaling for High-Speed Optical Communication Systems

In this paper, the performance of a novel multilevel signaling based on Manchester code namely four-level Manchester Coding (4-MC) technique is investigated for next generation high-speed optical fiber communication links. The performance of 4-MC is studied and compared with conventional Manchester modulation and four-level pulse amplitude modulation (4-PAM) formats in terms of receiver sensitivity, spectral efficiency and dispersion tolerance at the bit rate of 40 Gb/s. The bit error rate (BER) calculation model for the proposed multilevel scheme has also been developed. The calculated receiver sensitivity and the chromatic dispersion tolerance at the BER of 10–9 of the proposed scheme are −22 dBm and 67.5 ps/nm, respectively. It is observed that, 4-MC scheme is superior in comparison to 4-PAM by 3.5 dB in terms of receiver sensitivity in back-to-back scenario. Therefore, the proposed scheme can be considered as an alternative to current 4-PAM system.