Nyquist OTDM/DWDM Transmission

With the rapid development of optical communication technology, the demand for information is increasing, how to maximize optical transmission system capacity and improve spectral efficiency has become a research hotspot in optical communications. In this paper, the optical filter in the transmitter is introduced, the purpose is conducting spectral shaping to achieve minimization of the bandwidth, which can reduce the channel spacing and improve the spectral efficiency. In this paper, theoretical and simulation analysis of different optical filters are introduced, the main research results are as follows:An effective program has been designed that can improve the spectral efficiency of optical fiber communication systems with a dynamic tunable optical filter.The simulation model of40Gbit/s OTDM system is completed, simulation analysis for optical filters are conducted in OTDM system. The signal bandwidth with different optical filters including Rectangular filter, Butterworth filter, Bessel filter, Gaussian filter and Trapezoidal filter has been compared, and then the performance of different filters are summarized.Simulation experiments are took in OTDM/WDM system, the minimum channel spacing for different filters are studied. Different filter types, different bandwidths, the minimum channel spacing are different. The results show that the performance of Gaussian optical filter is the best. In contrast, Butterworth optical filter and Bessel optical filter are worse. The simulation result is instructive for improving the existing experiment system and achieving high spectral efficiency.