Tantalum pentoxide

Dielectric metasurfaces, which consist of planar arrays of subwavelength dielectric structures that collectively mimic the operation of traditional bulk optics, have revolutionized the field of optics due to their potential for building high-efficiency, multi-functional chip-based optoelectronic systems. The properties of dielectric metasurfaces are largely determined by the materials they are made of, and they are highly desirable to have a high refractive index, low optical loss, and wide bandgap while being easy to fabricate. Here, we present a new material platform based on tantalum pentoxide (Ta2O5) for the realization of high-performance dielectric metasurface optics in the ultraviolet and visible spectral regions. This wide bandgap dielectric exhibits a high refractive index of more than 2.1 and a negligible extinction coefficient over the entire broad spectrum, which can be easily deposited over large areas with good quality using direct physical vapor deposition and patterned into high aspect ratio sub-wavelength nanostructures by the usual methods. - Can be etched with fluorine gas reaction ions. We have implemented a range of highly efficient UV and Vis metasurfaces with representative light field modulation capabilities, including polarization-independent high numerical aperture lenses, spin-selective holographic projections, and vivid structured color generation, with up to 80% operating efficiency. Our work overcomes the scalability of commonly used metasurface dielectrics and the limitations of their operation in the visible and ultraviolet spectral ranges, and provides a new avenue for high-performance, robust, and foundry-capable metasurface optics.