Equalization of Fiber Optic Channels

The performance of fiber optic communication links is often limited by a phenomenon know as dispersion, which causes optical pulses to broaden as they propagate through the fiber, thus giving rise to intersymbol interference (ISI). Migration towards greater speed and longer links in fiber optic systems augment problems with dispersion in optical fibers, and dispersion compensation is consequently an increasingly important issue. One method of compensating for ISI, which has proven to be effective in for example radio communications, is equalization of the received signal. This technique is however yet to be implemented in fiber optic systems. This thesis investigates the possibilities of using adaptive electronic equalization to compensate for ISI caused by dispersion in optical fibers. Simulations are performed using realistic hardware models of various equalizer configurations in order to determine a feasible implementation. Both trained and blind equalizers are considered. The results of these simulations show considerable improvement of the signal quality after equalization, even with fairly restrained hardware designs