We propose a low-speed photonic sampling for independent high-frequency characterization of a Mach–Zehnder modulator (MZM) and a photodetector (PD) in an optical link. A low-speed mode-locked laser diode (MLLD) provides an ultra-wideband optical stimulus with scalable frequency range, working as the photonic sampling source of the link. The uneven spectrum lines of the MLLD are firstly characterized with symmetric modulation within the interesting frequency range. Then, the electro-optic modulated signals are down-converted to the first Nyquist frequency range, yielding the self-referenced extraction of modulation depth and half-wave voltage of the MZM without correcting the responsivity fluctuation of the PD in the link. Finally, the frequency responsivity of the PD is self-referenced measured under null modulation of the MZM. As frequency responses of the MZM and the PD can be independently obtained, our method allows self-referenced high-frequency measurement for a high-speed optical link. In the proof-of-concept experiment, a 96.9 MS/s MLLD is used for measuring a MZM and a PD within the frequency range up to 50 GHz. The consistency between our method and the conventional method verifies that the ultra-wideband and self-referenced high-frequency characterization of high-speed MZMs and PDs.

我们提出了一种低速光子采样，用于对光链路中的马赫-曾德调制器 (MZM) 和光电探测器 (PD) 进行独立的高频表征。低速锁模激光二极管 (MLLD) 提供具有可扩展频率范围的超宽带光学激励，用作链路的​​光子采样源。MLLD 的不均匀谱线首先以感兴趣的频率范围内的对称调制为特征。然后，将电光调制信号下变频到第一奈奎斯特频率范围，在不校正链路中PD响应率波动的情况下，产生MZM调制深度和半波电压的自参考提取。最后，PD 的频率响应度是在 MZM 的零调制下自参考测量的。由于可以独立获得 MZM 和 PD 的频率响应，我们的方法允许对高速光链路进行自参考高频测量。在概念验证实验中，使用 96.9 MS/s MLLD 来测量高达 50 GHz 频率范围内的 MZM 和 PD。我们的方法与传统方法的一致性验证了高速 MZM 和 PD 的超宽带和自参考高频特性。