Compact, Spatial-mode-interaction-free, Ultralow-loss, Nonlinear photonic integrated circuits

We implement Euler bends to build compact high-Q Si3N4 racetrack microresonators, featuring a small footprint of only 0.21 mm(2) for 19.8 GHz FSR. We demonstrate that these multi-mode microresonators can be operated in the single-mode regime and generate a single soliton microcomb. (C) 2022. The Author(s)