American Journal of Engineering Research (AJER) 2014 www.ajer.org Page 225 American Journal of Engineering Research (AJER) e-ISSN : 2320-0847 p-ISSN : 2320-0936 Volume-03, Issue-03, pp-225-229 www.ajer.org Research Paper Open Access Threshold based Bit Error Rate Optimization in Four Wave Mixing Optical WDM Systems Karamjeet Kaur Abstract: - Optical communication is communication at a distance using light to carry information which can be performed visually or by using electronic devices. The trend toward higher bit rates in light-wave communication has interest in dispersion-shifted fibre to reduce dispersion penalties. At an equivalent time optical amplifiers have exaggerated interest in wavelength multiplexing. This paper describes optical communication systems where we discuss different optical multiplexing schemes. The effect of channel power depletion due to generation of Four Wave Mixing waves and the effect of FWM cross talk on the performance of a WDM receiver has been studied in this paper. The main focus is to minimize Bit Error Rate to increase the QoS of the optical WDM system. I. INTRODUCTION Since the mid 90’s, optical fibers have been used for point to point communication at a very high speed. Fiber-optic communication is a method of transmitting information from one place to another by sending light through an optical fiber. Fiber-optic communication systems have revolutionized the telecommunications industry and played a major role in the advent of the information age. Often the optical fiber offers much higher speed than the speed of electronic signal processing at both ends of the fiber. Because of its advantages over electrical transmission the use of optical fiber has largely replaced copper wire communication in the developed world. The main benefits of fiber are it exceptionally low loss with allowing long distances between amplifiers and repeaters and its inherently high data-carrying capacity such that thousands of electrical links would be required to replace a single high bandwidth fiber. The another benefit of fiber is that even when run alongside each other for long distances and fiber cables experience effectively no crosstalk in contrast to some type of electrical transmission lines. Other main advantages of the optical fiber communication are the large capacity, high speed and high reliability by the use of the broadband of the optical fiber. Huge bandwidth of optical fiber communication system can be utilized to its maximum by using multiple access techniques. OPTICAL wavelength division multiplexing (WDM) networks are very promising due to their large bandwidth with their large flexibility and the possibility to upgrade the existing optical fiber networks to WDM networks [2]. WDM has already been introduced in commercial systems. All-optical cross connects (OXC), however, have not yet been used for the routing of the signals in any of these commercial systems. A number of OXC topologies have been introduced but their use has so far been limited to field trials and usually with a small number of input–output fibers & wavelength channels. The practical systems have many signals and wavelength channels which influence each other and cause significant crosstalk in the optical cross connect that has probably prevented the use of OXC’s in commercial systems. The crosstalk levels in OXC configurations presented so far are generally so high that they give rise to significant signal degradation and to an increased bit error probability. Because of the complexity of an OXC is different when sources of crosstalk exist and this makes it difficult to optimize the component parameters for minimum total crosstalk. Optical communication is any form of telecommunication that uses light as a transmission medium. Optical communication system consists of a transmitter which encodes a message into an optical signal channel which carries the signal to its destination and a receiver which reproduces the message from the received optical signal. Optical communication systems are used to provide high-speed communication connections [1]. Optical communication is one of the newest and most advanced forms of communication by electromagnetic waves. It differs from radio and microwave communication only in the sense that the wavelengths employed are shorter or equivalently or the frequencies employed are higher. In another very real sense it differs markedly from these