The numerical simulation of optical fiber communication systems

With the increase of transmitted bit rate and channel power in optical fiber communication systems, nonlinear effects in the optical fiber begin to show significant influence on system performance. These effects can no longer be neglected in system analysis and evaluations. However, inclusion of these effects dramatically increases the complexity in system modeling and thus makes the analytical approaches much less efficient and even inaccurate in some cases. The numerical simulation becomes a critical tool in optical fiber communication system designs and evaluations.; We developed a simulation package for optical communication systems. The fiber loss, dispersion, nonlinearities and the polarization mode-dispersion (PMD) are included in the simulation model. Optical components and electrical components are also included in the model. A set of nonlinear coupled-equations is derived for the fiber model, which includes all the significant effects encountered in real systems. Most existing nonlinear coupling equations are special cases of this set of equations and can be directly derived from them. A new numerical method, called inverse split-step Fourier (ISSF) method is also derived for inverse problems of the fiber communication systems, which performs the inverse operations to the traditional split-step Fourier (SSF) method. The simulation software was developed using a high level language, MatlabTM with graphical user-interfaces based on the Simulink TM platform. The simulation package can be used for simulations of both time-division multiplexing (TDM) systems and wavelength-division multiplexing (WDM) systems with either birefringent fiber or non-birefringent fiber.; The verification and validation of the simulation model was performed by comparing simulated results to either analytical results, published results or measured results from experiments. Several experiments were performed with different fiber types, different bit rates and different link lengths. As case studies, the simulation package has been used for studying nonlinear effects in single-mode fiber and performing evaluations on wavelength-division multiplexing (WDM) systems. From the first study, new formulas are derived for intensity-dependent FWM and two nonlinear methods for measuring PMD are created. From the second study, the compatibility of non-return-to-zero (NRZ) signals with solitons in WDM systems is predicted and problems that arose from real system testing were solved.