由于相干光正交频分复用(CO-OFDM)系统具有很高的峰均功率比(PAPR)以及非常近的子载波间隔，使得光纤非线性损伤成为系统的决定因素。提出中间位置光学相位共轭(OPC)补偿算法补偿CO-OFDM的Kerr损伤，由于OPC两端链路对称，可以最大限度地保证满足补偿条件，具有很好的非线性补偿效果。而且无链路色散补偿和有链路色散补偿系统均适用。该算法能使单信道40 Gb/s CO-OFDM的最大Q因子提高3 dB，非线性阈值提高4 dB；波分复用(WDM)系统的最大Q因子能提高1.1 dB，非线性阈值提高1 dB。

Due to high peak-to-average power ratio (PAPR) and the nearest subcarrier spacing, fiber nonlinearity impairment becomes the determining factor of coherent optical orthogonal frequency-division multiplexing (CO-OFDM) systems. Midlink optical phase conjugation (M-OPC) is used to compensate for the fiber Kerr nonlinearity effect in CO-OFDM systems. Because of the symmetry of both ends of the link, OPC can best meet the conditions of compensation and has best nonlinearity compensation effect. And OPC can be applied to link with and without online dispersion compensation. Through OPC for 40 Gb/s single channel system, the maximum Q can be increased by 3 dB, and the nonlinear threshold (NLT) (for Q>10 dB) is increased by 4 dB. For wavelength division multiplex (WDM) system, the maximum Q can be increased by 3 dB and NLT is increased by 1 dB.