Abstract:

We report on the generation of soliton frequency combs in microring resonators with a waveguide cross-section consisting of two 400-nm-thick layers of silicon nitride with a width difference of 100 nm. Soliton combs spanning from 1450 to 1670 nm are achieved with a pump power at 1550 nm of around 100 mW in the input waveguide. A counterpropagating auxiliary pump differing in frequency from the soliton pump by a few times the resonator’s free spectral range is used for thermal stabilisation, allowing manual tuning into the few-soliton and single-soliton states.