Interferometric Crosstalk Mitigation By Phase Scrambling In DWDM

Using optical add/drop multiplexer and cross-connecter for optical switching is the developing direction of DWDM networks. But the non-ideal filtering and switching performance of an optical node will inevitably cause linear crosstalk. The interferometric crosstalk in linear crosstalk, which has the same nominal wavelength with the desired signal, will be located in the electrical receiver bandwidth. Moreover, it will propagate with the desired signals along optical network, accumulate in optical nodes, cause an even more serious degradation in system performance. So the interferometric crosstalk constitutes a major limiting factor for the scalability of optical networks. Further more, DWDM systems impose strict requirement on optical crosstalk isolation with comprising elements. For instance, crosstalk isolation levels better than 35dB should be used to guarantee power penalties smaller than 1dB with even a small number of crosstalk sources, which is still a high requirement for integrated optical switches and cross connects at the current technology level.Phase scrambling, an interferometric crosstalk mitigation technique, is reported to be capable of improving system tolerance to crosstalk. As is reported, in a 2.5Gbps link of 100 km and 200 km, power penalties smaller than 2dB for crosstalk up to -15 dB and -16 dB are measured, and this corresponds to an improvement of system tolerance to crosstalk of 7dB and 5.3dB, respectively. This result demonstrates the feasibility of phase scrambling in optical network with current integrated optical technology.In this thesis, phase scrambling is analysed for systems of higher bit rates, e.g. 10Gbps. Simulation results show that, in 10Gbps back to back local systems, the improvement of system tolerance to crosstalk is 5dB...