The study of the propagation effects that currently limit the performance of optical communication networks, allows implementing techniques that increase the capacity such as optical phase modulation and digital signal processing compensation. In this article we analyze the chromatic dispersion and nonlinearities for intensity and phase modulated signals including data bit rates of 40 and 100 Gbps. The analysis is done employing numerical simulation techniques such as split step Fourier transform (SSF) and split step in the time domain (SSTD), to resolve the nonlinear Schrodinger equation (NLSE). We obtain the accuracy comparing with analytical results, and we analyze the SSTD method in different fiber link scenarios including phase modulation and high data bit rates.