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差分相移键控(DPSK)和差分正交相移键控(DQPSK)对光纤非线性具有很高的容忍度,且灵敏度高,在高速、高频谱效率系统中具有优越性。提出了一种基于双驱动马赫-曾德尔调制器(MZM)的差分正交相移键控归零码(RZ-DQPSK)和差分正交相移键控载波抑制归零码(CSRZ-DQPSK)信号产生的新方法。利用一个双驱动MZM实现DQPSK调制,另一个MZM实现波形切割,生成RZ/CSRZ-DQPSK信号。给出了详细的理论推导过程。该方法简化了高速RZ/CSRZ-DQPSK光信号的产生过程,减少了调制器个数。仿真结果表明,CSRZ-DQPSK信号载波频率分量被抑制,具有比RZ-DQPSK信号更紧凑的频谱结构,采用平衡相干检测接收方法接收到的信号有清晰的眼图。
Differential phase shift keying (DPSK) and differential quadrature phase shift keying (DQPSK) have high tolerance to fiber nonlinearity and high sensitivity, and are superior in high speed and high spectral efficiency systems. This paper presents a scheme of differential quadrature phase-shift keying zero-return code (RZ-DQPSK) and differential quadrature phase-shift keying carrier suppression zeroing code (CSRZ-DQPSK) based on dual-drive Mach- Zehnder modulator New method of signal generation. DQPSK modulation is implemented with one dual-drive MZM and the other MZM is used for waveform cutting to generate RZ / CSRZ-DQPSK signals. Gives a detailed theoretical derivation process. This method simplifies the generation of high speed RZ / CSRZ-DQPSK optical signals and reduces the number of modulators. The simulation results show that the CSRZ-DQPSK signal carrier frequency components are suppressed and have a more compact spectrum structure than the RZ-DQPSK signal. The signal received by the balanced coherent detection receiving method has a clear eye diagram.