High-temperature metal coating for modification of photonic band edge position

Abstract

Atomic-layer-deposited iridium is coated onto three-dimensional tungsten woodpile photonic crystals to modify the optical properties of the structure. As the lattice constant of a metallic photonic bandgap structure decreases to the scale of the near-IR wavelengths, the band edge becomes pinned and cannot be pushed to shorter wavelengths because of limitations inherent in the material. With a thin coating of iridium, the band edge of a pinned tungsten lattice is pushed from ~1.6 μm to below 1 μm. This shift in the reflectance band edge will be accompanied by a reduction in the absorptance of the structure in the 1-2 μm range.