An integrated 3C-silicon carbide-on-insulator photonic platform for nonlinear and quantum light sources

Silicon carbide (SiC) polytypes are emerging for integrated nonlinear and quantum photonics due to their wide-bandgap energies, second-order optic nonlinearity and process compatibility with complementary metal-oxide-semiconductor technologies. Among polytypes, 3C-SiC is the only one epitaxially grown on wafer-scale silicon substrates. However, on-chip nonlinear and quantum light sources leveraging the second-order nonlinearity of 3C-SiC have not been reported to our knowledge. Here, we design and fabricate an elliptical microring on 3C-SiC. We demonstrate a nonlinear light source with a second-harmonic generation efficiency of \(17.4\pm 0.2 \% {W}^{-1}\) $17.4\pm 0.2\%W^{-1}$ and difference-frequency generation with a signal-idler bandwidth of 97 nm. We demonstrate a spontaneous parametric down-conversion source with a photon-pair generation rate of 4.8 MHz and a coincidence-to-accidental ratio of \(3361\pm 84\) $3361\pm 84$ . We measure a low heralded single-photon second-order coherence \({g}_{H}^{\left(2\right)}=0.0007\) $g_H^{\left(2\right)}=0.0007$ . We observe time-bin entanglement with a visibility of \(86.0\pm 2.4 \%\) $86.0\pm 2.4\%$ using this source. Our work paves a way toward SiC-based on-chip nonlinear and quantum photonic circuits.