Photonic generation of frequency-doubled microwave waveforms based on cascaded Mach-Zehnder modulator

摘要

In this paper, a photonic method to generate frequency-doubled microwave waveforms based on cascaded Mach-Zehnder modulator were proposed and experimentally demonstrated. Cascaded modulation were used to generate the +/- 1st-order sidebands with carrier suppression and +/- 3rdorder sidebands with +/- 1st-order sidebands suppression, which were polarization multiplexed and photodetected to generate the 2nd-order and 6th-order electrical harmonics. By properly adjusting the amplitude ratio of the 2nd-order and 6th-order harmonic signals, frequency-doubled triangle and square microwave waveforms were simulated. And a 2 GHz triangle and square waveform was realized in the experiment as a proof of concept, with RMSEs of 0.0989 and 0.3906 respectively. In addition, the effect of extinction ratio and modulation index of the modulator on RMSE were investigated. The results show that the proposed system is of such advantages as simple structure, easy implementation, low cost and flexible frequency tunability.