Operando probing of microresonator thermal tuning in dissipative Kerr solitons

The thermal tuning of microresonators is crucial for the accessibility and long-term stability of soliton microcombs. We propose an equivalent resonance probing method that enables operando probing of thermal tuning throughout the soliton generation process. A probe laser, ingeniously Pound–Drever–Hall-locked to a resonance adjacent to the pumped resonance, is used to indirectly monitor the pumped resonance evolution by beating with an atom-referenced pump laser. We characterize the thermal-tuning-induced frequency steps of resonance and the repetition rate with a temperature resolution of 11.3 μK at 1 s averaging time and extract the thermal coupling coefficient of the soliton microcomb to be 2.6 MHz/K. Using these calibrated parameters, we further implement active thermal stabilization that sustains a single soliton for 10 h. Our work provides deep insight into microresonator thermal tuning and offers an efficient pathway for thermal management of soliton microcomb systems.