Chen Haoyu, Ma Jianxin
Appl Opt. 2021 Sep 20;60(27):8299-8306. doi: 10.1364/AO.433353.
We have proposed a photonic waveform generation scheme based on a dual-polarization Mach-Zehnder modulator (DPol-MZM). In this scheme, a dual-frequency optical signal generated by RF optical carrier suppression modulation via a Mach-Zehnder modulator (MZM) is divided into two beams; one is further modulated by the RF signal via a DPol-MZM to generate ±1st and ±3rd-order sidebands, and the other is further modulated by the RF signal via a second MZM to generate ±2nd-order sidebands. After two modulated optical signals are detected by a balanced photodiode, the second, fourth, and sixth-order harmonics without cross-beating terms are generated in the differential photocurrent. Since the harmonic amplitudes can be controlled independently by the optical power of the two optical beams and the DC biases of the DPol-MZM, the waveforms can be tuned conveniently. Based on the simulation, frequency-doubled triangular, rectangular, and sawtooth waveforms with a full-duty cycle at a repetition rate of 20 GHz are successfully generated with their harmonic amplitude ratio in the electric spectrum close to the ideal amplitude ratio, and the symmetry of the triangular waveform from 20% to 80% is tuned.
我们提出了一种基于双偏振马赫-曾德尔调制器（DPol-MZM）的光子波形生成方案。在该方案中，通过马赫-曾德尔调制器（MZM）进行射频光载波抑制调制产生的双频光信号被分为两束；一束通过DPol-MZM进一步被射频信号调制以产生±1阶和±3阶边带，另一束通过第二个MZM进一步被射频信号调制以产生±2阶边带。在两个调制光信号由平衡光电二极管检测后，在差分光电流中产生没有交叉拍频项的二阶、四阶和六阶谐波。由于谐波幅度可以通过两束光的光功率和DPol-MZM的直流偏置独立控制，因此波形可以方便地调谐。基于仿真，成功生成了重复频率为20 GHz、占空比为100%的倍频三角波、矩形波和锯齿波，其电频谱中的谐波幅度比接近理想幅度比，并且对三角波从20%到80%的对称性进行了调谐。
