Metasurfaces enable the full control of electromagnetic waves over a wide spectrum. High‐efficiency transmissive metasurfaces have been demonstrated up to the visible frequencies by using dielectrics. However, extending the operating spectrum to the ultraviolet range is challenging. This is due to the strong absorption in typical dielectric materials and the inexhaustive understanding of the magnetic resonances in dielectric nanostructures. Here, a large‐bandgap material—niobium pentoxide (Nb2O5)—is introduced to engineer the ultraviolet geometric meta‐holograms to achieve a total efficiency of 79.6% at 355 nm wavelength. The employed orientation‐varying nanobricks, operating as miniaturized half‐waveplates (HWPs), are elaborately designed to excite the antiferromagnetic modes that maintain Ex component of the incident light via even antiparallel magnetic dipoles (AMDs) but reverse Ey component via odd AMDs, thereby unveiling the underlying mechanism of dielectric nano‐HWPs. By adding the polarization degree of freedom, an ultra‐channel meta‐hologram, multiplexing two orthogonal spin channels while exhibiting three outputs, is demonstrated experimentally for ultraviolet vectorial anti‐counterfeiting. This work might open the door toward high‐performance ultraviolet nanophotonics and meta‐optics.

Dielectric optical nanoantennas are promising as fundamental building blocks in next generation color displays, metasurface holograms, and wavefront shaping optical devices. Due to the high refractive index of the nanoantenna material, they support geometry-dependent Mie resonances in the visible spectrum. Although phase change materials, such as the germanium–antimony–tellurium alloys, and post-transition metal oxides, such as ITO, have been used to tune antennas in the near-infrared spectrum, reversibly tuning the response of dielectric antennas in the visible spectrum remains challenging. In this paper, we designed and experimentally demonstrated dielectric nanodisc arrays exhibiting reversible tunability of Mie resonances in the visible spectrum. We achieved tunability by exploiting phase transitions in Sb2S3 nanodiscs. Mie resonances within the nanodisc give rise to structural colors in the reflection mode. Crystallization and laser-induced amorphization of these Sb2S3 resonators allow the colors to be switched back and forth. These tunable Sb2S3 nanoantenna arrays could enable the next generation of high-resolution color displays, holographic displays, and miniature LiDAR systems.

Digital camera sensors use color filters on photodiodes to achieve color selectivity. As the color filters and photosensitive silicon layers are separate elements, these sensors suffer from optical cross-talk, which sets limits to the minimum pixel size. Here, we report hybrid silicon-aluminum nanostructures in the extreme limit of zero distance between color filters and sensors. This design could essentially achieve submicrometer pixel dimensions and minimize the optical cross-talk arising from tilt illuminations. The designed hybrid silicon-aluminum nanostructure has dual functionalities. Crucially, it supports a hybrid Mie-plasmon resonance of magnetic dipole to achieve color-selective light absorption, generating electron hole pairs. Simultaneously, the silicon-aluminum interface forms a Schottky barrier for charge separation and photodetection. This design potentially replaces the traditional dye-based filters for camera sensors at ultrahigh pixel densities with advanced functionalities in sensing polarization and directionality, and UV selectivity via interband plasmons of silicon.