Dissipative Kerr soliton formation in silicon microring resonators in the 2 μm wavelength range

Chip-scale optical frequency combs (OFCs) have had significant impact in the fields of coherent communications, metrology, and optical sensing. Various approaches to chip-scale OFC generation have been explored, with OFC generation through third-order nonlinear optical processes in microresonators showing considerable promise. In particular, dissipative Kerr soliton (DKS) formation in integrated microresonators has enabled the generation of highly coherent, broadband, high repetition rate OFCs. To date, the majority of work on DKS generation has focused on silicon nitride resonators pumped at telecommunication wavelengths. However, the silicon platform still holds substantial promise due to its order of magnitude stronger nonlinear coefficient and its potential for simple dispersion engineering, enabling access to wavelengths beyond 2 μm. In this work, we present a theoretical study of DKS generation in silicon microring resonators pumped in the 2 μm wavelength range. This platform enables low threshold power OFC generation in the mid-IR and leverages CMOS-compatible silicon photonics. We demonstrate the formation of breather, multiple and single bright soliton states, as well as zero-dispersion soliton states. These states are accessed with milliwatt level pump powers and can produce OFC bandwidths exceeding one octave, highlighting the potential for a broad range of applications.