Collision-induced rogue waves and universal transport dynamics in chaotic Kerr microresonators

Coherently driven optical microresonators with Kerr nonlinearity have received intense interest since they host various nonlinear optical states including solitons and chaos. Recently, chaotic modulational instabilities (MIs)-a state far from equilibrium-have been exploited for parallel ranging and random number generation. Despite theoretical predictions suggesting unconventional wave statistics in chaotic MI, its rapidly varying temporal waveforms have prohibited direct experimental assessment. Here, we use a frequency-agile optical frequency comb to coherently interrogate the optical field within the microresonator in both temporal and spectral domains. In the chaotic regime, we observe transient events characterized by extremely high optical intensity, identified as rogue waves based on the long-tailed distribution of peak powers. Statistical analysis of many rogue wave events reveals their origin as pulse collisions. Our full-field measurement further unveils universal correlated photon transport that determines the collision process.