Ultralow-loss tightly confining Si3N4 waveguides and high-Q microresonators

Efficient nonlinear phenomena in integrated waveguides imply the realization in a nonlinear material of tightly confining waveguides sustaining guided modes with a small effective area with ultra-low propagation losses as well as high-power damage thresholds. However, when the waveguide cross-sectional dimensions keep shrinking, propagation losses and the probability of failure events tend to increase dramatically. In this work, we report both the fabrication and testing of high-confinement, ultralow-loss silicon nitride waveguides and resonators showing average attenuation coefficients as low as similar to 3 dB/m across the S-, C-, and L bands for 1.6-mu m-width x 800-nm-height dimensions, with intrinsic quality factors approaching similar to 10(7) in the C band. The present technology results in very high cross-wafer device performance uniformities, low thermal susceptibility, and high power damage thresholds. In particular, we developed here an optimized fully subtractive process introducing a novel chemical-physical multistep annealing and encapsulation fabrication method, resulting in high quality Si3N4-based photonic integrated circuits for energy-efficient nonlinear photonics and quantum optics. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement