Optimized two-layer motheye structures for MgAl 2 O 4 spinel ceramic windows

We computationally study two-layer motheye nanostructures fabricated on MgAl2O4 spinel ceramic windows. We investigated the parameters of the structure, including height, width, and shape, in order to optimize its power transmission efficiency over a broad bandwidth. We found a two-layer motheye structure in which the cones of the upper structure have a concave shape that can theoretically achieve more than 99.8% transmission at normal incidence in the wavelength range between 0.4 μm and 5.0 μm.