Performance enhancement of long haul ultra dense WDM systems

Abstract

The burgeoning demand for broadband services such as database queries, home shopping, video-on-demand, remote education, telemedicine and video conferencing has pushed the existing networks to their limits. This demand was mainly fueled by the brisk proliferation of Personal Computers (PC) together with the exceptional increases in their storage capacity and processing capabilities and the widespread availability of the internet. Hence, the necessity, to develop high-speed optical technologies in order to construct large capacity networks arises. Two of the most popular multiplexing techniques available in the optical domain that are used in the building of such high capacity networks, are Wavelength Division Multiplexing (WDM) and Optical Time Division Multiplexing (OTDM). Dense Wavelength Division Multiplexing (DWDM) has drastically increased the capacity of optical transmission systems. Its inherent advantages have made it the current favorite multiplexing technology for optical networks. OTDM has made it possible to increase the bit rate transmissions on single wavelengths. Therefore, merging these two techniques to get very high-speed hybrid WDM/OTDM networks brings about the merits of both multiplexing technologies. These optical multiplexing technologies would solve the quotfiber exhaust problem and is expected to be the core technology in the all-optical networks of the future. An optical fiber enables the transmission of many signals over long distances because of its huge transmission bandwidth (in THz) and low losses window of operation. Long Haul links are prone to losses and attenuation which forms the major limiting factor imposed by optical components or by fiber which degrades the system performance and limits the appreciable reach of the signals. In order to compensate for these effects, opto-electronic regenerators were used to perform the 3R of Reshaping, Retiming and Retransmitting the signal. Unfortunately it has also resulted in increased cost of the system.