Photonic Damascene process for integrated high-Q microresonator based nonlinear photonics

Abstract

High confinement, integrated silicon nitride (SiN) waveguides have recently\nemerged as attractive platform for on-chip nonlinear optical devices. The\nfabrication of high-Q SiN microresonators with anomalous group velocity\ndispersion (GVD) has enabled broadband nonlinear optical frequency comb\ngeneration. Such frequency combs have been successfully applied in coherent\ncommunication and ultrashort pulse generation. However, the reliable\nfabrication of high confinement waveguides from stoichiometric, high stress SiN\nremains challenging. Here we present a novel photonic Damascene fabrication\nprocess enabling the use of substrate topography for stress control and thin\nfilm crack prevention. With close to unity sample yield we fabricate\nmicroresonators with $1.35\\,\\mu\\mathrm{m}$ thick waveguides and optical Q\nfactors of $3.7\\times10^{6}$ and demonstrate single temporal dissipative Kerr\nsoliton (DKS) based coherent optical frequency comb generation. Our newly\ndeveloped process is interesting also for other material platforms, photonic\nintegration and mid infrared Kerr comb generation.\n