EXPLOITATION OF THE FIBER CAPACITY IN OPTICALLY AMPLIFIED TRANSMISSION-SYSTEMS

As is well known, single-mode optical fibers have a huge optical bandw idth but the exploitation of this optical ether for optical transmissi on systems is limited by several degrading effects that are present bo th in the fiber and in other devices composing the link. However, in r ecent years several techniques have been proposed and tested to show h ow the system capacity can approach total exploitation of the fiber ba ndwidth. In this work we survey the main optically amplified communica tion systems that have been proposed to achieve very-high-capacity tra nsmission and analyze their performances by means of numerical simulat ions. Numerical simulation is a fundamental tool for the study of opti cal communication because analytical theories are not able to take int o consideration all the effects that are simultaneously present in a r eal link. The study reports a comparison among the performance of digi tal intensity modulation systems with direct detection considering bot h the nonreturn-to-zero and the return-to-zero (soliton) format, as we ll as the time and wavelength division multiplexing techniques. The re sults show how exploitation of the Kerr nonlinearity, use of the in-li ne filtering process, and introduction of dispersion management are th e best means to limit the degrading effects of chromatic dispersion an d ASE noise. (C) 1998 Academic Press.