Technological advances on Si and Si3N4 low-losses waveguide platforms for nonlinear and quantum optics applications

In this communication, we report on the design, fabrication, and testing of silicon-on-insulator (SOI) and silicon-nitrideon- insulator (SiNOI) photonic circuits for nonlinear and quantum optics applications. As recently demonstrated, the generation of correlated photons on Si platforms can be used for quantum cryptography and quantum computing. Concerning SiNOI waveguides, Kerr frequency combs have been proposed in many applications, such as atomic clocks, on-chip spectroscopy, and terabit coherent communications. Silicon is an attractive platforms for correlated photons sources because of its high nonlinearity, they can have several modes in telecom band with sharp line widths (tens of μeV) and its inherent complementary metal-oxide-semiconductor (CMOS) compatibility. Moreover, the SiNOI is an attractive platform for Kerr comb generation due to their large bandgap and consequently the low two-photon absorption in the telecommunication band. Furthermore, in all the previous SiNOI-based frequency combs, the silicon nitride film undergoes long and high-temperature annealing to reduce the absorption in the telecommunication band caused by the dangling N-H bonds, thus making such annealed Si3N4 films non-CMOS compatible. However, both in the case of correlated photons pairs generation and Kerr frequency combs, the source efficiency is related to the quality factor (Q), so that a high-Q resonator is required to get highly-efficient sources. Authors report here about the fabrication and the characterization of annealing-free CMOS-compatible SiNOI- and hydrogen-annealed silicon-based waveguides and microresonators featuring ultra-low losses (e.g., 0.6 dB/cm for single-mode Si waveguides) that can be used, respectively, as efficient sources for Kerr combs and correlated photon pairs sources.