Compact, spatial-mode-interaction-free, ultralow-loss, nonlinear photonic integrated circuits

Abstract Multi-mode waveguides are ubiquitously used in integrated photonics. Although interaction among different spatial waveguide eigenmodes can induce novel nonlinear phenomena, mode is typically undesired. Adiabatic bends, such as Euler have been favoured to suppress interaction. Here, we adapt and optimize bends build compact racetrack microresonators based on ultralow-loss, multi-mode, silicon nitride photonic circuits. The feature a footprint of only 0.21 mm 2 for 19.8 GHz free spectral range, suitable tight integration. We quantitatively investigate the suppression with bends. show that low optical loss rate (15.5 MHz) preserved, par strength (25 MHz). This results an unperturbed microresonator dispersion profile. further generate single dissipative Kerr soliton repetition without complex laser tuning schemes or auxiliary lasers. optimized be building blocks systems, well linear circuits programmable processors quantum computing.