Photonic Generation of Radio-Frequency Waveforms Based on Dual-Parallel Mach–Zehnder Modulator

We report a photonic approach to generating radio-frequency (RF) waveforms based on a dual-parallel Mach-Zehnder modulator (DPMZM) driven by a sinusoidal RF signal. One of the sub-MZMs (MZM1) of the DPMZM is driven by the sinusoidal RF signal, whereas the other sub-MZM (MZM2) has no driven signal. In this way, the powers of even- and odd-order sidebands can be separately controlled by adjusting the bias of the MZM1. The power ratio between the odd- (or even-) order sidebands is tunable by adjusting the RF power. Moreover, the power and the phase of the optical carrier can be independently tunable by adjusting the biases of the MZM2 and the parent MZM of the DPMZM, respectively. After detecting by a photodetector, an RF signal with controllable harmonics is generated. Thus, a desired RF waveform can be generated by separately manipulating its harmonics. The proposed method is theoretically analyzed. In addition, proof-of-concept experiments are carried out to generate triangular and rectangular waveforms with repetition rates of 5 and 10 GHz.