A STUDY OF FOUR WAVE MIXING NONLINEAR EFFECT ON VARIOUS FIBER TYPES IN DWDM OPTICAL SYSTEMS

摘要

Dense Wavelength Division Multiplexing (DWDM) transport systems are highly attractive in today's telecommunication scenario since they offer large capacity with a small number of channels and also achieve high spectrum efficiency. Fiber nonlinearities can have a serious impact on the performance of these systems. The presence of nonlinearities causes the channel capacity to be a nonmonotonic function of the input signal strength. The information throughput can be increased by using dispersion shifted fiber having minimum loss and zero dispersion at 1.55 μm wavelength and Er-doped optical fiber amplifiers in the fiber links. But low dispersion and high intensity of the signal launched enhance the four wave mixing, a third order nonlinear effect. Due to this low dispersion and high intensity of light pulse, frequency mixing is made in an efficient manner and new wavelength are generated. This is called four wave mixing penalty. If one of the generated new wavelength is equal to signal wavelength in the DWDM modulated carrier, the interference or cross-talk is produced and that will reduce the signal to noise ratio at the receiver side: To the best of the author's knowledge and with reference to the literature we have presented in this paper, how the inter modulation products are generated due to four wave mixing effect and are observed experimentally using single mode fiber also simulation is made with dispersion shifted fiber for two channel and sixteen channel wavelength division multiplexed transmission system. In addition, FWM power (cross-talk) is evaluated and compared for three major types of fibers like single mode fiber, dispersion shifted fiber, non-zero dispersion shifted fiber.