Iridium processing of metasurfaces for infrared optical applications

Iridium (Ir) is a refractory metal commonly seen in industrial applications, but has great potential for optical applications including metasurfaces. Metasurfaces are used to control the optical properties of an interface via sub-wavelength surface structures. These patterns require sharply defined features to create precise optical phase interactions. For high-temperature environments, most materials are insufficient candidates for metasurfaces because the sharpness of the surface structures are lost due to edge-rounding or oxidation. Ir is better suited for metasurface applications in high-temperature environments but the patterning of Ir using nanofabrication techniques has not been thoroughly investigated. In this work, Ir metasurfaces were fabricated and characterized for optical applications in the infrared.