Manipulation of In-Plane Hyperbolic Phonon Polaritons for Configurable Focusing

作者：Jun Liang, Jiaqi Zhu, Yanyu Zhao, Siyu Wang, Youning Gong, Yupeng Zhang, Guo Ping Wang · 发表于：ACS Photonics · 年份：2024 · DOI：10.1021/acsphotonics.4c01707 · 被引用次数：6 · 研究领域：Thermal Radiation and Cooling Technologies、Mechanical and Optical Resonators、Plasmonic and Surface Plasmon Research

In-plane hyperbolic phonon polaritons (HPhPs) in biaxial α-phase molybdenum trioxide (α-MoO 3 ) hold great promise for light manipulation at the deeply subwavelength scale. However, achieving configurable focal lengths for these in-plane HPhPs remains a significant challenge due to the intrinsically dispersive nature of α-MoO 3 . In this study, a vertically stacked van der Waals heterostructure is fabricated by placing α-MoO 3 on the top of tellurium (Te), a dielectric with a large refractive index in the mid-infrared region, to engineer the in-plane hyperbolic dispersion of polaritons in α-MoO 3 . HPhPs in this heterostructure exhibit Te-thickness-dependent dispersion, enabling configurable in-plane focusing with focal lengths ranging from 2.29 to 5.61 μm. Moreover, this configurable in-plane focusing consistently maintains the focal spot size within a deeply subwavelength range, approximately 1/20 of the free-space wavelength. We envision that these findings provide a feasible approach to effectively manipulate in-plane HPhPs via dispersion engineering, with potential applications in planar meta-optics and optical sensing.