摘要
相干光正交频分复用(CO-OFDM)对光纤链路中的色度色散(CD)和偏振模色散(PMD)具有较强的容忍性,但是OFDM信号高峰均功率比(PAPR)的特点使其对光纤非线性效应非常敏感,严重影响了系统传输性能。本文提出了基于恒包络(CE)调制的方法使得系统中光信号PAPR降低为0dB,从而提高了CO-OFDM系统的非线性传输性能。仿真结果表明,子载波采用16QAM调制的40Gbit/s单信道CE调制CO-OFDM系统,在经800km无色散补偿、欠色散补偿和周期全色散补偿标准单模光纤(SSMF)链路传输后,虽然较传统CO-OFDM存在约1.8dB的代价,但是系统最大发射光功率分别提高了6.2、9.3和10.9dB。并且,将本文方案应用到CO-OFDM和10Gbit/s NRZ-OOK混合传输WDM系统中,信道最大发射光功率仍获得了5.2dB的提高。因此,本文提出的CE调制方法能有效地提高CO-OFDM系统在不同传输环境中的光纤非线性容限。
Coherent optical orthogonal frequency division multiplexing （CO-OFDM） can immune to chro- matic dispersion （CD） and polarization mode dispersion （PMD） in fiber links. However, the large peak- to-average power ratio （PAPR） of OFDM signals makes it susceptible to fiber nonlinearities and conse- quently degrades the transmission performance. In this paper, an approach based on constant envelope （CE） modulation,which can lower the PAPR of the optical signal to 0 dB,is proposed to improve the fi- ber nonlinear performance for CO-OFDM systems. Simulation results show that after 800 km standard single-mode fiber （SSMF） transmission, the maximum launch power of the proposed 40 Gbit/s CE-CO- OFDM system with 16-QAM subcarrier modulation is improved by 6.2 dB,9. 3 dB and 10.9 dB com- pared with conventional CO-OFDM for the dispersion map without dispersion compensation fiber （DCF）, the 100 ps/nrn under-compensated and the fully periodic compensation dispersion maps, respec- tively, although an optical signal-to-noise ratio （OSNR） penalty of - 1.8 dB is observed in the linear re- gion of transmissions. When the scheme is utilized in the hybrid wavelength division multiplexing （WDM） transmission of the 40 Gbit/s CO-OFDM channel with 10 Gbit/s NRZ-OOK channels,a 5.2 dB increase of the maximum launch power is also observed. Therefore,the proposed scheme can effec- tively improve the fiber nonlinear tolerance for CO-OFDM systems in different transmission scenarios.
出处
《光电子．激光》
EI
CAS
CSCD
北大核心
2013年第10期1922-1929,共8页
Journal of Optoelectronics·Laser
基金
国家自然科学基金(61071097
61107060)
高等学校博士点基金(20090185110010)资助项目
关键词
光纤通信
相干光正交频分复用(CO—OFDM)
恒包络(CE)调制
峰均功率比(PAPR)
光纤非线性
fiber optics communication
coherent optical orthogonal frequency division multiplexing （CO- OFDM）
constant envelope （CE） modulatiom peak-to-average power ratio （PAPR）
fiber nonlinearity
