Photonic Microwave Waveforms Generation Based on Frequency and Time-Domain Synthesis

In this paper, a novel photonic microwave waveform generation method with both frequency-domain synthesis (FDS) and time-domain synthesis (TDS) is proposed, for the first time to the best of our knowledge, by using cascaded modulation and an optoelectronic oscillator. By controlling the spectral lines in a polarization-modulated optoelectronic oscillator (P-M-OEO), a triangular waveform is generated according to the FDS, where a parallel part of the optimum modulation axis of the Mach- Zehnder modulator (MZM) executes carrier suppression in the P-M-OEO, while its orthogonal part is left unmodulated. A quasi-rectangular waveform is then generated by directly modulating another MZM at the quadrature point. Additionally, a sawtooth or reversed-sawtooth waveform with 50% duty cycle and 100% duty cycle can be generated in TDS. In the experiment, a 3-GHz triangular waveform, a 3-GHz high-quality microwave signal, a 6-GHz frequency doubling signal, a 3-GHz quasi-rectangular waveform, a 3-GHz 50% duty cycle sawtooth or reversed-sawtooth waveform, and a 100% duty cycle sawtooth or reversed-sawtooth with frequency doubling are obtained simultaneously. The results verify the feasibility of the proposed scheme, and it holds a potential candidate for applications in photonic microwave signals.