由于相干光正交频分复用（CO-OFDM）系统很高的峰均功率比（PAPR）以及非常近的子载波间隔，使得链路色散导致的子载波走离对光纤非线性损伤的影响更加明显。研究了不同色散分布、不同残余色散情况下，无色散补偿光纤（DCF）和有色散补偿光纤的光纤链路时CO-OFDM系统的非线性损伤以及系统性能。针对单信道40 Gb/s CO-OFDM系统，无DCF链路比完全补偿DCF链路，Q因子高5.1 dB；对于DCF链路，当残余色散从0变为到1200 ps/nm时，最大Q因子提高了4 dB，非线性阈值提高了4 dBm，1200 ps/nm时性能几乎和无色散补偿系统相同。

Due to the high peak-to-average power ratio (PAPR) and the very close sub-carrier spacing for coherent optical orthogonal frequency division multiplexing (CO-OFDM) system, the sub-carriers walking-away resulted by link dispersion greatly affects the nonlinear damage of the optical fiber. We firstly study the nonlinear damage and system performance of CO-OFDM system without/with dispersion compensating optical fiber (DCF) under the conditions of different distributions of dispersion and different residual dispersion. For the single channel 40 Gb/s CO-OFDM system, the Q factor of DCF link is 5.1 dB higher than that of completely compensated DCF link. For DCF link, when the residual dispersion is added from 0 to 1200 ps/nm, the maximum Q factor is improved by 4 dB, and the nonlinear threshold is increased by 4 dBm. When the residual dispersion is 1200 ps/nm, the performance of DCF link system is almost the same as the system without DCF.