Deterministic Soliton Crystal Dual-Microcomb Generation in Coupled Nonlinear Microcavities by Tuning the Coupling Coefficient

Microcavity based optical frequency combs (microcombs) can be used for applications such as dual-comb spectroscopy [1] and ultra-fast optical ranging [2]. For dual frequency comb applications, the two frequency combs in general are generated using two separate microcomb sources so that the detuning of the two pumps can be tuned independently. However, synchronous tuning of the two pumps is experimentally challenging. In this paper, we propose a new dual-microcomb generation scheme by using coupled microcavities. Instead of tuning the cw pump laser, the microcombs are generated by tuning the coupling between the two coupled microcavities. As a result, when the coupled microcavity system is pumped by two separate pumps, synchronously tuning of the two pumps is not required for dual-microcomb generation.