Comparative study of the performance of CATV channels over DWDM network using direct and external modulator

Different parameters that can be adjusted to obtain an acceptable performance for a Dense Wavelength Division Multiplexing (DWDM) network are considered. A comparison of various parameter settings between the external and direct optical modulation is made based on the simulation results. Different effects caused by varying the electrical power, while setting optical modulation index, is vital. A trade-off between higher signal to noise ratio and nonlinearity effect should be taken into account for sending radio frequency signals over a fiber channel. Several simulation results for transmitting 30 Cable Television (CATV) channels, 64-QAM modulated, over a DWDM network are given in order to find the best adjustments for the link parameters of both internal and external optical modulations. Two of the basic parameters, focused in this article, include the electrical power and optical modulation index.