Tungsten based optical absorber

Utilizing metamaterials, electromagnetic waves can be manipulated to mimic the behavior of various devices depending on the real part of effective permittivity. The imaginary part of the permittivity, which is undesirable for most applications, is suitable for absorbers. Metamaterial absorbers fully exploit the loss mechanisms and provide high absorptance at their operational wavelength. Amongst absorbers, optical absorbers are sought out for their numerous applications in optical filters, color filters, and solar thermophotovoltaics. In this paper, we present a simulative work for tungsten-based broadband optical absorber, which provides high absorptance throughout the optical regime (400-800 nm). This absorber employs a simplistic design of cross nano-resonator built up from Tungsten metal. Tungsten is used as the metal layer for the design due to its high melting point of 3422°C, which provides the absorber with high thermal stability. This high absorptance achieved by design is also explained thoroughly. It is further shown that this absorber is angle insensitive. Moreover, some variations of the design are also shown that can also achieve similar results, which shows the tolerance of the design towards fabrication errors.