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 $$17.4\pm 0.2 \% {W}^{-1}$$ 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 $$3361\pm 84$$ . We measure a low heralded single-photon second-order coherence $${g}_{H}^{\left(2\right)}=0.0007$$ . We observe time-bin entanglement with a visibility of $$86.0\pm 2.4 \%$$ using this source. Our work paves a way toward SiC-based on-chip nonlinear and quantum photonic circuits. Silicon carbide polytypes (SiC) exhibit second-order optic nonlinearity to act as on-chip nonlinear and quantum light sources, but their integration is typically challenging. The authors demonstrate the performance of 3C-SiC --a fully integrable polytype-- as an on-chip quantum light source based on its second-order susceptibility.