Diverse interlocked switching waves in cavity-enhanced second-harmonic generation

We investigate the intriguing dynamics and existence conditions of temporal two-color flat-top solitons, termed interlocked switching waves (ISWs), in driven quadratic microresonators via a phase-matched second-harmonic generation process. We show that the formation of two-color ISWs relies strongly upon the pump frequency detuning, the group-velocity dispersion, and the temporal walk-off, and that the ISWs at the negative detuning may behave differently from the ones formed at the positive detuning, due to the asymmetric modulation instability of homogeneous steady-state solutions. In contrast to previous predictions, stable ISW states are found to occur as well on interacting harmonics that both have anomalous group-velocity dispersions when prepared at the negative detuning. Moreover, we unveil that large temporal walk-off contributes to the formation of two-color ISWs at the positive detuning but tends to deteriorate at the negative detuning. Our results help improve our understanding of two-color ISWs and thereby pave the way for highly efficient octave-spanning dual-band comb generation.