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We report four-wave mixing with different polarization and spatial modes in a single 4H-silicon carbide photonic device. Our device shows great potential to perform high-dimensional multiplexing for optical communication and high-dimensional entanglement in quantum networks. We use a polarization-insensitive grating coupler and a multimode microring resonator that supports three polarization and spatial mode resonances. Finally, we show the polarization dependence of the third-order nonlinearity of 4H-silicon carbide. The measured nonlinear refractive index of the light polarized along the extraordinary axis, which is n2,TM = (13.1 ± 0.7) × 10−19 m2/W, is twice as large as that of the light polarized along the ordinary plane, n2,TE = (7.0 ± 0.3) × 10−19 m2/W, indicating that the extraordinary polarization is more efficient for nonlinear experiments in the 4H-silicon carbide integrated platforms as compared to the ordinary polarization.

Silicon carbide (SiC), having various intrinsic color centers, is a highly promising optical materials for making monolithic quantum integrated photonic circuits, by combining the single-photon sources with the integrated photonic components in SiC integrated platforms. Based on this quantum-material platform, we propose polarization-independent 1 × 2 and 2 × 2 multimode interference based beam splitters and Mach-Zehnder interferometers (MZI) for single-photon manipulation with unknown polarization states. We experimentally demonstrate that these devices exhibit excellent performances with incident light at both high power (>-10 dBm) and ultra-low power (<-100 dBm). The 1 × 2 and 2 × 2 beam splitters have low average loss of 1 dB and 1.5 dB, with a wide bandwidth of >100 nm and >70 nm, respectively. The MZI exhibits high transmittance, with a visibility of 98.3% and 97.6% for the high-power measurement and an even higher visibility of 99.0 ± 0.4% and 98.7 ± 0.6% for the ultra-low power measurement, for the TE and TM polarizations, respectively.

Silicon carbide (SiC) is emerging rapidly in novel photonic applications thanks to its unique photonic properties facilitated by the advances of nanotechnologies such as nanofabrication and nanofilm transfer. This review paper will start with the introduction of exceptional optical properties of silicon carbide. Then, a key structure, i.e., silicon carbide on insulator stack (SiCOI), is discussed which lays solid fundament for tight light confinement and strong light-SiC interaction in high quality factor and low volume optical cavities. As examples, microring resonator, microdisk and photonic crystal cavities are summarized in terms of quality (Q) factor, volume and polytypes. A main challenge for SiC photonic application is complementary metal-oxide-semiconductor (CMOS) compatibility and low-loss material growth. The state-of-the-art SiC with different polytypes and growth methods are reviewed and a roadmap for the loss reduction is predicted for photonic applications. Combining the fact that SiC possesses many different color centers with the SiCOI platform, SiC is also deemed to be a very competitive platform for future quantum photonic integrated circuit applications. Its perspectives and potential impacts are included at the end of this review paper.