The Broadband Optical Absorption Performance of Rod‐Based Hyperbolic Metamaterials in Cuboidal Patterns

Abstract The development of metamaterials for advanced optical functions, especially optical metamaterials that can be synthesized through a colloidal assembly route, holds significance in nanophotonic research. A broadband absorber based on hyperbolic metamaterials (HMMs) with cuboidal patterns, constructed using 3D assembled nanorod arrays, is fabricated with the assistance of SU‐8 photoresist filling, photolithography, and atomic layer deposition (ALD) of Pt. The formation of cuboidal patterns creates a rod‐based metamaterial waveguide, enabling slow‐light dispersion in the visible frequency range. Slow light frequencies can be adjusted by varying the metal thickness and metal type, while they are minimally influenced by the width of each cuboidal framework. In addition to the absorption attributed to the rod metamaterial waveguides, the gap between the neighboring cuboidal frameworks induces a coupling effect that enhances light capture. The presence of curving morphologies on the side of each cuboidal framework further enhances optical absorption. The optimized broadband rod metamaterial absorber in cuboidal patterns can achieve an average absorptivity of 96.9% in the 400–1100 nm wavelength range.