Kerr nonlinearity-assisted quadratic microcomb

Generation of nonlinear frequency combs in chi ((3)) optical microresonators has attracted tremendous research interest during the last decade. Recently, realization of the microcomb owing to chi((2)) optical nonlinearity in the microresonator promises new breakthroughs and is a big scientific challenge. Moreover, it is of high scientific interest that the presence of both second- and third-order nonlinearities results in complex cavity dynamics. In particular, the role of chi((3)) nonlinearity in the generation of the quadratic microcomb is still far from being well understood. Here, we demonstrate the interaction between the second- and third-order nonlinearity in the lithium niobate microresonator, which can provide a new way of phase matching to control the mode-locking condition and pulse number for the quadratic microcomb. Our results verify that the Kerr nonlinearity can benefit the quadratic microcomb. The principle can be further extended to other material platforms to provide more manipulation methods for comb generation based on chi ((2)) nonlinearity at mid-infrared.

Automated summary

The generation of nonlinear frequency combs in chi((3)) optical microresonators has attracted significant research interest. The recent development of microcomb based on chi((2)) optical nonlinearity holds promise for breakthroughs and presents a major scientific challenge. The presence of both second- and third-order nonlinearities results in complex cavity dynamics.