Turn-key Kerr soliton generation and tunable microwave synthesizer in dual-mode Si₃N₄ microresonators

This study investigates the thermal compensation mechanism in dual-mode Si₃N₄ microresonators that demonstrates the ease of generation of single-solitons with nearly octave-wide spectral bandwidth. The deterministic creation of soliton frequency combs is achieved by merely switching the wavelength of a tunable laser or a semiconductor diode laser in a single step. The pump frequency detuning range that can sustain the soliton state is 30 gigahertz (GHz), which is approximately 100 times the resonance linewidth. Interestingly, these dual-mode resonators also support the coexistence of primary combs and solitons, enabling their utilization as functional microwave synthesizers. Furthermore, these resonators readily facilitate the generation of diverse multi-solitons and soliton crystals. This work presents a simplified system to access high-performance and versatile Kerr solitons, with wide-ranging applications in optical metrology, microwave photonics, and LiDAR.