Normal transmission via plasmon-polariton coupling in anisotropic hyperbolic dispersive media under wide...

Our paper reports on a layered hyperbolic metamaterial (HMM) composed of alternating Ag/TiO₂ films, designed to achieve high ultraviolet (UV) transmittance with large critical-angle guiding. The multilayer exhibits hyperbolic iso-frequency contours (IFCs) in the UV regime, and the flattened curvature enables efficient beam transmission across a broad angular range, thereby overcoming the diffraction limit. Within the 374-400 nm interval, the HMM demonstrates a high transmittance band above 85%, with a peak of 91% at 385 nm, surpassing the performance of indium tin oxide (ITO) in UV. Remarkably, high transmittance is maintained for incidence angles up to 60°. This wide-angle, high-transmission response arises from enhanced structural plasmon-polariton coupling in the hyperbolic regime, where incident light excites plasmons at successive interfaces, leading to interlayer coupling, energy accumulation, and subsequent release. Time-domain field analysis reveals that the release process exhibits an ultrafast decay time of 3.46 fs, underscoring the potential of this platform for fast response and high normal transmittance UV optoelectronic devices.