| With the rapid development of the global economy, information communication has become more and more frequent. Especially in recent years, the wide expanding of the Internet have constantly emerged in a number of new communication services, such as video on demand (VOD), video communication, data transmission of sensing, telepresence, cloud computing, and etc. To meet the increasing demand of the information transmission, construction of network infrastructure should be continuously strengthened, and at the same time, advanced high-speed digital optical transmission systems are desired to be employed, such as 40Gb/s, 100Gb/s,160Gb/s. As the transmission capacity of single channel increased, effects of dispersion and nonlinearity of the system are more serious. Novel optical modulation technique has become one of the key technologies to mitigate the transmission impairments in high-speed optical transmission system. Available optical frequency band have been expanded, and meanwhile, high spectra efficiency modulation formats are expected. Therefore, multi-level modulation technologies have attracted more and more attention. Analysis on modulation of 40-Gb/s high-speed optical transmission system is proposed in this paper. Firstly, principles of intensity modulation and phase are studied, and generation methods of intensity modulation signal and phase modulation signal are introduced and the demodulation principles are studied. Secondly, simulation analysis on the effects of dispersion and nonlinearity on the intensity modulation and phase modulation signal is demonstrated. Finally, joint intensity and phase modulation and demodulation schemes and the transmission performance are studied and analyzed. Results showed that 70% IRZ-DQPSK not only has high spectrum efficiency and has better has better dispersion and nonlinearity performance. |
PDF Full Text Request