▎ 摘　　要

Graphene is a two-dimensional material with intriguing electrical and optical properties for infrared photonic devices. However, single layer graphene (SLG) suffers from a very low optical absorption of similar to 1-2% depending on the substrate, which significantly limits its efficiency as photonic devices. In this Letter, we address this challenge by coating SLG with self-assembled, pseudoperiodic ultrahigh refractive index (n = 8-9 at lambda = 1600-5000 nm) semimetal Sn nanostructures for highly effective, broad-band infrared photon management in SLG, offering a new approach for light trapping beyond plasmonics and high refractive index dielectric photonics. The infrared absorption in SLG on fused quartz (SiO2) is greatly increased from <1.5% to >15% in a very broad spectral range of lambda = 900-2000 nm due to the near-field electromagnetic interactions between the ultrahigh refractive index Sn nanostructures and SLG, a significant advantage over relatively narrow-band plasmonic resonances for photon management in SLG. The optical absorption enhancement in SLG has also been confirmed by field-enhanced Raman peaks from SLG and supported by higher photoconductivities both at an infrared wavelength of lambda = 1550 nm and at a visible wavelength of lambda = 650 nm. This work also opens the door to the investigations of ultrahigh refractive index semimetal nanostructures for nanoscale photon management.