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For low-cost and high chromatic dispersion (CD) robustness single sideband (SSB) with direct detection (DD), three schemes of SSB with pulse amplitude modulation (PAM) were investigated.Among that, the highest spectral efficiency was achieved by the scheme of adding the frequency down-conversion at the transmitter.However, that scheme reduces the tolerance for laser linewidth.Hence, based on the character of the SSB-PAM signal, a DSP scheme was proposed, including a modified equalization algorithm with phase distortion immunity and blind phase search algorithm.The simulation results show that the modified scheme can tolerate 1 MHz linewidth for 112 Gbit/s SSB-PAM-DD, while the original scheme for SSB-PAM was only 100 kHz at the same bit error rate (BER) threshold.Therefore, the proposed scheme can achieve a high frequency efficiency, high linewidth tolerance, and low-cost SSB-PAM signaling transmission.

For low-cost and high chromatic dispersion (CD) robustness single sideband (SSB) with direct detection (DD), three schemes of SSB with pulse amplitude modulation (PAM) were investigated.Among that, the highest spectral efficiency was achieved by the scheme of adding the frequency down-conversion at the transmitter.However, that scheme reduces the tolerance for laser linewidth.Hence, based on the character of the SSB-PAM signal, a DSP scheme was proposed, including a modified equalization algorithm with phase distortion immunity and blind phase search algorithm.The simulation results show that the modified scheme can tolerate 1 MHz linewidth for 112 Gbit/s SSB-PAM-DD, while the original scheme for SSB-PAM was only 100 kHz at the same bit error rate (BER) threshold.Therefore, the proposed scheme can achieve a high frequency efficiency, high linewidth tolerance, and low-cost SSB-PAM signaling transmission.

In order to satisfy the demand of the efficiency and low cost measurement for high rate optical communication system,the IQ-ImEstimation algorithm was proposed for IQ imbalance estimation in the PDM-MQAM cohernt optical communication system based on GSOP.Two estimation schemes include amplitude impairment and phase impairment were designed by utilizing the power and correlation.Finally,a 34 GBaud PDM-MQAM system was simulated and experimentalized.The results indicate that the IQ-ImEstimation algorithm is accuracy and effective.

In order to satisfy the demand of the efficiency and low cost measurement for high rate optical communication system,the IQ-ImEstimation algorithm was proposed for IQ imbalance estimation in the PDM-MQAM cohernt optical communication system based on GSOP.Two estimation schemes include amplitude impairment and phase impairment were designed by utilizing the power and correlation.Finally,a 34 GBaud PDM-MQAM system was simulated and experimentalized.The results indicate that the IQ-ImEstimation algorithm is accuracy and effective.