提出一种基于级联马赫-曾德尔调制器(MZM)的载频连续可调相位编码波形光产生方法。该方法通过设置级联MZM的直流偏置点和调制指数,实现对±4阶光边带的选取,通过控制施加在级联MZM上的射频驱动信号相位,可在非平衡时间脉冲整形(UTPS)系统的输出端产生倍频系数为16的相位编码信号。通过调整UTPS系统中两个线性调频布拉格光栅的色散值,可实现对相位编码信号载频的连续调谐。仿真中利用2 GHz的射频信号分别生成了载频为32 GHz和19.2 GHz的相位编码信号。仿真验证了所提方法的有效性,也验证了生成的信号具有较好的压缩性。

A photonic approach for generating phase-coded waveform with continuously tunable carrier frequency based on cascaded Mach-Zehnder modulators (MZMs) is proposed. By setting the direct-current bias point and modulation index of the cascaded MZMs, we can select ±4 th-order optical sidebands. Finally, a phase-coded signal with a frequency multiplication coefficient of 16 can be generated at the output of the unbalanced temporal pulse shaping (UTPS) system through the controlling of the phase of the radio frequency driving signal applied to the cascade MZMs. In addition, when the dispersion values of the two linear chirped fiber Bragg gratings in the UTPS system are adjusted to be appropriate, the carrier frequency of phase-coded signal can be continuously tunable. Phase-coded signals with the carrier frequencies of 32 GHz and 19.2 GHz are generated with a 2 GHz radio frequency signal in the simulation. The simulation demonstrate the effectiveness of the proposed method, and also shows superior compression of the generated signal.