Description
Hyperbolic shear modes enable extreme optical confinement and directional propagation, but their implementation remains challenging. Natural materials offer limited design flexibility, while artificial twist-based structures rely on interlayer coupling that is acutely sensitive to thickness mismatch, interface contamination, twist-angle inhomogeneity, and lattice strain, resulting in degraded shear performance. Here we establish a single-sheet-integrated paradigm for hyperbolic shear metasurfaces based on Td-WTe2 skew-rectangle arrays. These low-symmetry plasmonic resonators support detuned, non-orthogonal dual localized surface plasmon resonances in the far-infrared range. Polarization-resolved Fourier transform infrared spectroscopy confirms the coexistence of two geometrically controlled resonances with polarization axes spanning a 140° tuning range. The emergence of hyperbolic shear surface waves exhibiting both axial dispersion and loss redistribution is collectively confirmed by finite-element simulations of surface waves, analytical isofrequency contours derived from Maxwell’s equations, and random phase approximation calculations. We further reveal that the shear phenomenon arises from the superposition of intrinsic crystalline anisotropy and extrinsic geometric anisotropy. By integrating dual resonances within a single patterned sheet, this approach ensures intrinsic mode coupling with guaranteed robustness, and more importantly, enables independent tuning through multiple geometric degrees of freedom. Our study establishes a universal design platform for hyperbolic shear nanophotonics, which readily extends to diverse anisotropic plasmonic materials.
