We report on radiofrequency techniques to reliably generate and control dissipative-Kerr- soliton microresonator frequency combs. Since the pump-laser frequency detuning to the resonator primarily determines the soliton dynamics, we devise an offset Pound-Drever-Hall frequency-locking system to directly stabilize and tune it with RF precision. Our technique not only provides deterministic feedback to guide Kerr-soliton formation from a cold cavity, but it enables systematic exploration of the detuning-dependent thermal and nonlinear processes that govern the frequency comb provided to users for applications and opens a path to decouple the repetition and carrier-envelope-offset frequencies of the comb. In particular, we demonstrate phase stabilization of both these degrees-of-freedom with a single-soliton Kerr comb to a fractional frequency precision below 10^-14^, commensurate with modern optical-timekeeping technology. Moreover, we investigate the use of microcombs for low-noise microwave signal generation in which residual detuning noise is a fundamental limitation in the microwave spectral purity.
Physical Review Letters
microresonator, microresonator frequency comb, nonlinear optics, photonics