Optical Fibers And Amplifiers For Wdm Systems

The development of optical-fiber amplifiers allowed a dramatic increase in the capacity of optical transmission systems while reducing system costs. Capacity increases are possible beacuse the high output powers afforded by optical-fiber amplifiers support higher bit rates, while their broad bandwidth and slow gain dynamics allow multichannel operation. This benefit comes at the expense of having to manage signal-to-noise ratio degradations due to the accumulation of amplifier noise and dispersion distortions accumulated over the total system link. Furthermore, nonlinear optical effects become significant over long lengths of fiber, causing cross talk among the different channels and increasing signal distortions.