Scaling the response of nanocrescent antennas into the ultraviolet

Fundamental resonance modes of nanocrescent optical antennas are associated with large electric fields at the crescent tips. These antennas have been extensively studied due to their relative ease of fabrication and tunable response via methods such as nanosphere template lithography. To date, investigations have only been performed in the visible to mid-infrared range, where the multimode anisotropic response has been documented both experimentally and through simulations. However, the presence of interband transitions in the dielectric response of the metals used for these studies complicates the analysis of the higher-order resonance modes. In this paper, we perform a comprehensive investigation of the electromagnetic response of aluminum nanocrescent antennas. Aluminum has an interband transition in the near-infrared that facilitates scaling of the resonance modes into the ultraviolet part of the spectrum, thus, allowing investigation of the higher-order modes of the nanocrescent structure. These high...