The proposed paper utilized the concept of Coherent detection. A field received by advances in Digital Signal Processing (DSP), has renewed interest in optical communication systems with spectrally efficient modulation formats. Starting with the point of view in comparison between the DP QPSK and DP 16-QAM analyses of Phase Noise in terms of Average Bit Error Rate (BER) and Optical Signal to Noise Ratio (OSNR) has been done. OSNR component is used in order to introduce noise in the dual

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... tion Optical coherent receiver system. The Noise is analyzed under the influence of different filters. Finally the best filter with best result have chosen in order to have minimum phase noise. To improve the performance of coherent receiver, a DSP algorithms like Constant Modulous Algorithm (CMA) and Blind phase search algorithm are used to compensate Propagation Mode Dispersion (PMD),Chromatic Dispersion (CD) and to achieve high data rate.