Si₃N₄-chip-based versatile photonic RF waveform generator with a wide tuning range of repetition rate

In this Letter, we demonstrate a ${{\rm Si}_3}{{\rm N}_4}$Si₃N₄-chip-based photonic approach to generate versatile radio frequency (RF) waveforms with a large tuning range of repetition rates. The amplitude and phase of the RF-phase-modulated signal are spectrally manipulated to synthesize Fourier coefficients of the desired RF waveforms by controlling the resonance conditions and frequencies of ${{\rm Si}_3}{{\rm N}_4}$Si₃N₄ optical ring resonators. Full-duty-cycle triangular, square, and sawtooth waveforms with widely tunable repetition rates from 1 to 13 GHz were experimentally generated.