Analytical modeling to evaluate the effect of cross phase modulation on WDM optical Networks

In the modern world of technology, data rates up to 40 Gb/s are becoming a reality and the bandwidth hungry applications such as teleconferencing, telemedicine, IPTV have already begun to make their presence in the commercial market. These bandwidth hungry applications attract the need for optical communications in which the fibers can theoretically provide infinite bandwidth. In order to satisfy such needs, one of the solutions that can be put into effect is the concept of DWDM (Dense Wavelength Division Multiplexing) which involves transmitting multiple wavelengths spaced very close to each other and thereby providing higher bandwidth efficiency. In case of DWDM, the wavelength channels are very close to each other in the order of 0.4 nm or lower. As a result of closely spaced wavelengths, there will be crosstalk and other detrimental effects. This provides the underlying concept for this thesis, which is developing an analytical model for evaluating the optical system performance. In case of DWDM, the signal power of one wavelength phase modulates the other closely traveling wavelength channel. This phase modulation can then be converted into time jitter through a chromatic dispersion of the fiber which reduces the performance of the optical system. The information carrying capacity of the fiber diminishes to a greater extent in case of higher powers. For higher data rates, higher powers are required and the system is more susceptive to this crosstalk effect. An analytical model is developed to evaluate the nonlinear time jitter introduced by cross phase modulation and the results are compared with numerical simulations using VPI simulation tool. They agree reasonably well.