Unraveling the generation dynamics of Brillouin-Kerr microcomb using a harmonically synchronized time magnifier

Dissipative Kerr soliton microcombs has become a revolutionary technology for diverse sensing applications. The Brillouin-Kerr soliton microcombs, with sub-femtosecond timing jitter under free-running conditions, shows great potential to serve ultra-precision optical sensing without excessive system complexity. However, due to the bandwidth limitations in opto-electronic detection equipment, its ultrafast dynamic generation process has never been clearly characterized experimentally. Here, we have constructed a harmonically synchronized time magnifier capable of singleshort waveform characterization with sub-ps time resolution and flexibly tunable measurement frame rate and observed the dynamic of BKS initiation from a flat background along with the real-time dynamics of controlling the generation of different numbers of solitons. This provides long-sought experimental verification for the theoretical study of BKS and enriches the physical understanding of the excitation process, which paves the way towards the practical application of ultra-low noise BKS microcomb in precision optical sensing.