OSNR monitoring for QPSK and 16-QAM systems in presence of fiber nonlinearities for digital coherent receivers
OSNR monitoring for QPSK and 16-QAM systems in presence of fiber nonlinearities for digital coherent receivers
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DOI：
10.1364/oe.20.019520
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发表时间：
2012-08-13
期刊：
影响因子：
3.8
通讯作者：
Lu, Chao
中科院分区：
文献类型：
--
作者：
Dong, Zhenhua;Lau, Alan Pak Tao;Lu, Chao
OSNR监测对于相干系统来说是必不可少的，它可以确保稳健、可靠的网络运行，并有可能为未来的动态光网络实现损伤感知路由。在具有色散（CD）和光纤非线性的长距离传输链路中，即使采用各种传输损伤补偿技术，也很难区分放大器噪声和光纤非线性引起的接收信号分布畸变，从而导致OSNR估计非常不准确。基于接收信号经过载波相位估计（CPE）后的分布特征，对相邻符号间非线性诱导的幅值噪声相关性进行表征，并将该信息纳入误差矢量幅值（EVM）计算中，实现光纤非线性不敏感OSNR监测。在传输链路1600公里、发射功率2 dBm的条件下，采用112gb /s极化复用正交相移键控技术（PM-QPSK）的OSNR监测范围为10 ~ 24db，最大估计误差小于1db。对于224gb /s的pm -16正交调幅（PM-16-QAM）系统，仿真结果表明OSNR监测范围为18 ~ 28db，最大估计误差小于1db。通过仿真研究了所提出的OSNR监测技术对不同脉冲形状、定时相位偏移、极化相关损耗（PDL）、极化模色散（PMD）和波分复用（WDM）效应的容限。(C) 2012美国光学学会
OSNR monitoring is indispensable for coherent systems to ensure robust, reliable network operation and potentially enable impairment-aware routing for future dynamic optical networks. In a long-haul transmission link with chromatic dispersion (CD) and fiber nonlinearity, it is difficult to distinguish between amplifier noise and fiber nonlinearity induced distortions from received signal distributions even after various transmission impairment compensation techniques, thus resulting in grossly inaccurate OSNR estimates. Based on the received signal distributions after carrier phase estimation (CPE), we propose to characterize the nonlinearity-induced amplitude noise correlation across neighboring symbols and incorporate such information into error vector magnitude (EVM) calculation to realize fiber nonlinearity-insensitive OSNR monitoring. For a transmission link up to 1600 km and signal launched power up to 2 dBm, experimental results for 112 Gb/s polarization-multiplexed quadrature phase-shift keying (PM-QPSK) demonstrate an OSNR monitoring range of 10-24 dB with a maximum estimation error below 1 dB. For 224 Gb/s PM-16-quadrature amplitude modulation (PM-16-QAM) systems, simulation results demonstrate an OSNR monitoring range of 18-28 dB with a maximum estimation error below 1 dB. Tolerance of the proposed OSNR monitoring technique to different pulse shapes, timing phase offsets, polarization dependent loss (PDL), polarization-mode dispersion (PMD) and WDM effects are also investigated through simulations. (C) 2012 Optical Society of America