Proceedings Article | 8 March 2019
KEYWORDS: Ultraviolet radiation, Optical components, Holograms, Infrared imaging, Phase shift keying, Dielectric polarization, Modulation, Electromagnetic radiation, Lenses, Beam splitters
Recent years have witnessed the rapid development of flat optical elements (i.e., metasurfaces). With properly designed and arranged sub-wavelength structures over its plane, a metasurface is able to impart arbitrary, spatially variant amplitude, phase and polarization modulations on an incident electromagnetic wave. This highly customizable nature allows metasurface to simultaneously accomplish a variety of functions that have traditionally been fulfilled by a combination of different optics, such as gratings, lenses, beam splitters, and hologram plates, with a significantly reduced physical thickness compared to traditional optical elements. Researchers have demonstrated various high-performance metasurfaces operating in the infrared (IR) and visible regime. However, there has been a conspicuous lack of work in the ultraviolet (UV) region, which is a spectral range hosting important applications such as photolithography, DNA sequencing, sterilization, and medical imaging. Unfortunately, direct translation to the UV regime of implementation strategies for IR and visible-frequency metasurfaces will not work, so new constituent materials and designs need to be developed.
Here, we report on high-efficiency, all-dielectric metasurfaces operating in the UV regime. The metasurfaces utilize wide bandgap (> 5.5 eV) dielectric materials, enabling the devices to operate over a broad-band UV range. We demonstrate metasurfaces working at three UV wavelengths (364, 325 and 266 nm), including hologram, lens, and self-accelerating beam devices. To further show the versatility of our design, we demonstrate metasurfaces producing spin-multiplexed holograms and self-accelerating beams at 364 nm, with operational efficiencies larger than 50%. Our work opens the door for high-performance and multi-functional UV flat optical elements.
