提出一种新的光反转归零码-差分正交相移键控(IRZ-DQPSK)调制方案,该方案所产生的IRZ信号相位连续,易于与相位调制信号相结合,占空比和消光比均可调。并仿真分析了单信道40 Gb/s长距离传输时,自相位调制(SPM)对幅移键控-差分正交相移键控(ASK-DQPSK)与IRZ-DQPSK两种信号的影响。结果表明,40 Gb/s长距离传输时,IRZ-DQPSK具有更好的抗SPM性能。
A novel scheme to generate inverse return-to-zero-differential quadrature phase-shift-keying(IRZ-DQPSK) modulation format is introduced.The IRZ signal generated in this scheme does not contain any original phase information,so it is convenient to combine IRZ modulation with the phase modulation,and both the duty cycle and the extinction ratio of the IRZ-DQPSK signal are tunable.The influence of self phase modulation(SPM) is compared between IRZ-DQPSK and amplitude shift keying-differential quadrature phase-shift-keying(ASK-DQPSK) in a 40Gb/s single channel long distance transmission by simulation.Results show that IRZ-DQPSK signal offers much better performance against SPM.