Bunching of temporal cavity solitons via forward Brillouin scattering

We report on the experimental observation of bunching dynamics with temporal cavity solitons (CSs) in a continuously-driven passive fibre resonator. Specifically, we excite a large number of ultrashort CSs with random temporal separations, and observe in real time how the initially random sequence self-organizes into regularly-spaced aggregates. To explain our experimental observations, we develop a simple theoretical model that allows long-range acoustically-induced interactions between a large number of temporal CSs to be simulated. Significantly, results from our simulations are in excellent agreement with our experimental observations, strongly suggesting that the soliton bunching dynamics arise from forward Brillouin scattering. In addition to confirming prior theoretical analyses and unveiling a new CS self-organization phenomenon, our findings elucidate the manner in which sound interacts with large ensembles of ultrashort pulses of light.