Break the efficiency limitations of dissipative Kerr soliton using nonlinear couplers

TL;DR

This paper introduces a nonlinear coupler approach to significantly improve the power conversion efficiency of dissipative Kerr solitons, overcoming traditional limitations and enabling near-unity efficiency in microresonator systems.

Contribution

The paper develops a generalized theoretical framework for nonlinear couplers, revealing efficiency limitations of conventional DKS pumping and proposing a practical nonlinear coupler method to enhance efficiency.

Findings

Predicted >90% conversion efficiency with nonlinear couplers in aluminum nitride microrings.

The approach applies to various nonlinear processes like Raman and Brillouin scattering.

Experimental feasibility demonstrated for high-efficiency DKS generation.

Abstract

Dissipative Kerr soliton (DKS) offers a compact solution of coherent comb sources and holds huge potential for applications, but has long been suffering from poor power conversion efficiency when driving by a continuous-wave laser. Here, a general approach to resolving this challenge is provided. By deriving the critical coupling condition of a multimode nonlinear optics system in a generalized theoretical framework, two efficiency limitations of the conventional pump method of DKS are revealed: the effective coupling rate is too small and is also power-dependent. Nonlinear couplers are proposed to sustain the DKS indirectly through nonlinear energy conversion processes, realizing a power-adaptive effective coupling rate to the DKS and matching the total dissipation rate of the system, which promises near-unity power conversion efficiencies. For instance, a conversion efficiency exceeding $90\:\%$ is predicted for aluminum nitride microrings with a nonlinear coupler utilizing second-harmonic generation. The nonlinear coupler approach for high-efficiency generation of DKS is experimentally feasible as its mechanism applies to various nonlinear processes, including Raman and Brillouin scattering, and thus paves the way of micro-solitons towards practical applications.