ISI and polarization switching in high bit rate optical fiber transmission systems

In the paper, there is investigated inter-symbol interference (ISI) in high bit rate optical transmission systems employing standard optical fibers with no dispersion compensation. Two types of systems are examined: a typical system with external light modulator and a system with additional polarization switching. The dependence of the optical path loss and horizontal eye pattern opening on the fiber length and input impulse shape is found for both the systems via computer simulation. The polarization switched system has better parameters for greater transmission distances (L > 70,..., 100 km) whereas for smaller distances the parameters for both systems are comparable. The optimum impulse shape that minimizes ISI is also found.