一种用于IMDD光系统的低复杂度非线性均衡器

Low complexity nonlinear equalizer for IMDD optical system

色散导致的信号相位变化经平方律检测后转化为非线性损伤,限制了C波段强度调制直接检测(IMDD)光系统性能。传统Volterra非线性均衡器(VNLE)可以补偿此类非线性损伤,但实现复杂度极高,不适合低成本、短距离传输系统。Neighbor-grouped Volterra非线性均衡器(NG-VNLE)通过简并具有相同系数的Volterra项从而大幅降低了实现复杂度,但简并操作也使得Volterra非线性项之间的差异被忽略,均衡性能有所下降。提出了一种用于IMDD光系统的低复杂度非线性均衡器,通过引入基于绝对值的非线性项,补偿了被忽略的Volterra项之间的差异;基于直调激光器(DML)的IMDD光系统的107 Gb/s四电平脉冲幅度调制(PAM4)C波段传输,测试了新提出的非线性均衡器性能,实验结果表明其性能与传统VNLE相近,且实现复杂度降低了28%。

The signal phase change caused by dispersion is transformed into nonlinear damage after square law detection,which limits the performance of C-band intensity modulated direct detection(IMDD)optical system.Traditional Volterra nonlinear equalizer(VNLE)can compensate such nonlinear damage,but its implementation complexity is very high,so it is not suitable for low-cost and short-distance transmission systems.Neighbor grouped Volterra nonlinear equalizer(NG-VNLE)greatly reduces the implementation complexity by degenerating Volterra terms with the same coefficients,but the degeneracy operation also ignores the differences between Volterra nonlinear terms and reduces the equalization performance.A low complexity nonlinear equalizer for IMDD optical system is proposed.By introducing the nonlinear term based on absolute value,the difference between the neglected Volterra term is compensated.A 107 Gb/s four-level pulse amplitude modulation(PAM4)C-band transmission of IMDD optical system based on directly modulated laser(DML)was carried out to test the performance of the proposed nonlinear equalizer.The experimental results show that it can achieve the performance similar to that of traditional VNLE,and the implementation complexity is reduced by 28%.