Hybrid vanadate silicon nanophotonic platform for extreme light management at telecom bands

We present a hybrid vanadate/silicon-photonics platform that integrates vanadate nanostructures with silicon-on-insulator (SOI) waveguides for high-performance functional passive building blocks at telecommunication wavelengths. Comprehensive numerical analysis is performed to study the mode hybridization in a hybrid waveguide structure that comprises a silicon ridge separated from a vanadate substrate. Studies on the impact of key geometric parameters reveal that the coupling between vanadate and photonic structures result in highly confined hybrid modes with extreme field confinement and significantly larger effective indices as compared to hybrid plasmon polarizations (HPPs) supported by noble-metal-based waveguiding systems. By leveraging the unique confinement and modal properties offered by vanadate material, we explore the feasibility of building ultra-compact waveguide attenuators and transverse-magnetic (TM)-pass polarizers based on proper combinations of vanadate and SOI configurations. Our studies indicate that a 5μm-long attenuator can simultaneously achieve over 30 dB absorption and a low optical return loss less than -27 dB for both transverse-electric (TE) and TM polarizations. In addition, through proper management of the interactions between vanadate and silicon modes with different polarizations, we numerically demonstrate an ultra-compact (3 μm) on-chip TM-pass polarizer featuring low insertion loss (~ 3 dB), in conjunction with an extinction ratio exceeding 22 dB. The integration of vanadate materials with SOI platforms thereby offers the potential to bridge a gap in conventional silicon photonic systems and opens new avenues towards scalable functional integrated silicon photonic devices at telecom bands.