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 new optical reverse-return-difference-differential quadrature phase-shift keying (IRZ-DQPSK) modulation scheme is proposed, in which the IRZ signals generated by the scheme are continuous in phase and easy to combine with the phase-modulated signals. The duty cycle and extinction Than adjustable. The effect of SPM on ASK-DQPSK and IRZ-DQPSK signals is also simulated and analyzed in single-channel 40 Gb / s long-distance transmission. The results show that IRZ-DQPSK has better anti-SPM performance at 40 Gb / s long distance transmission.