高速相干光接收机的全数字时钟恢复方案

All-Digital Timing Recovery Scheme for High-Speed Optical Coherent Receiver

时钟恢复是相干光接收机研究中的一个关键问题.首先对目前相干光接收机中有代表性的时钟恢复方案进行了分析,并针对解决现有方案中高采样率需求和非全数字实现的问题,提出一种新的适用于高速相干光接收机的时钟恢复方案.在所提方案中,将Gardner误差检测算法与插值滤波器相结合,使其具有算法复杂度低、可全数字化实现等优点.最后,在112Gbit/s偏振复用-非归零码-差分四相移键控(PM-NRZ-DQPSK)传输系统中对所提方案进行了仿真实验验证.仿真结果表明,所提的全数字时钟恢复方案在高速相干光接收机中能精确补偿由于本地采样时钟的频率和相位偏移带来的采样定时误差.

The existing representative timing recovery schemes is analyzed. And according to their prob- lems of high requirement of sample rate and non-all-digital implementation a new all-digital timing recovery scheme is presented for high-speed optical coherent receiver which combines Gardner timing-error detector and interpolator. The new scheme has a series of advantages, such as low complexity and all-digital realization, etc. Also, the good performance of the new scheme is demonstrated in a 112-Gbit/s polariza- tion multiplexed non-return-to-zero differential quadrature phase-shift keying （PM-NRZ-DQPSK） trans- mission system.