Research Of Adaptive Coherent Demodulation Techniques Based On Ultra High Resolution Optical Spectrum Analysis

Novel modulation format combining with coherent detection has become the mainsolution scheme to achieve ultra-high speed, ultra-large capacity and ultra-long haul opticaltransmission. However, the difference among modulation formats and transmission rates hasbrought us with huge difficulties to achieve the fusion of heterogeneous optical networks.Adaptive coherent demodulation, without any doubt, is the most promising method to solvethe above problem. As a result, this dissertation mainly focuses on adaptive demodulationtechniques based on the feature information acquired from high resolution optical spectrumanalysis. The main contents of the whole dissertation are as following.The principle and structure of an adaptive coherent demodulation system based onultra-high resolution optical spectrum analysis has been designed. An optical spectrumanalysis scheme based on stimulated Brillouin Scattering has been proposed. An adaptivecoherent demodulation method based on pattern recognition and feature extraction of opticalspectrum has also been proposed.An experimental device for high resolution optical spectrum analysis based onstimulated Brillouin scattering has been realized. Firstly, the experimental composition hasbeen described, which includes a tunable laser source, a high non-linear fiber, a photodetector, and a data acquisition card. Secondly, the realization of controlling andcommunicating among instruments has been elaborated. Finally, S-G smoothing algorithmand background noise suppression algorithm have been proposed to optimize the originalspectrum, the effect of the algorithms to the spectrum analysis performance has beencompared and analyzed.On the ground of ultra-high resolution spectrum analysis, adaptive coherentdemodulation simulation has been analyzed via obtaining feature parameters from spectrumpattern recognition. Firstly, the hardware implementation of adaptive coherent demodulationbased on ultra-high resolution optical spectrum analysis has been described. Secondly,relying on VPI TransmissionMaker and Altera DSP Builder, offline and online algorithms torealize polarization demultiplexing and phase recovery have been designed, the performanceof these algorithms has been analyzed and discussed.