In a recent paper, we show that a microresonator soliton frequency comb can be synchronized to an external reference laser through a nonlinear (Kerr-mediated) optical effect. This step of locking a frequency comb to a laser is a necessary one for various applications, such as optical frequency division in optical atomic clocks, and is typically accomplished through active feedback and servo control. We instead show that it is possible for synchronization to occur in an all-optical fashion. In addition to the significant simplification, we further show that the injection of the reference laser also increases the power on the opposite side of the frequency comb, which in the case of the octave-spanning combs that we work with, improves our ability to self-reference the comb and measure its carrier-envelope offset frequency.
This work was highlighted by a News and Views and in a JQI press release.
Ref: Kerr-induced synchronization of a cavity soliton to an optical reference, G. Moille, J. Stone, M. Chojnacky, R. Shrestha, U. Javid, C. Menyuk, and K. Srinivasan, Nature, 624, 8, (2023)