Numerical Characterization of Soliton Microcomb in an Athermal Hybrid Si3N4-TiO2 Microring.

We theoretically investigate the athermal constructions to cancel the thermorefractive effect of a hybrid Si3N4-TiO2 microring, which merges two materials with opposite thermo-optical coefficients (TOCs). The analytical and numerical results predict that the thermorefractive effect can be reduced under the appropriate parameters. In addition, the soliton state is easily accessed under the athermal condition. The thermorefractive noise due to the fluctuation of the microresonator temperature caused by the heat exchange between the microresonator and the surrounding environment is also suppressed by one order of magnitude, which is critical for the potential applications of soliton microcombs, such as spectroscopy, optical clocks and microwave generation.