Computational design and geometry-driven modeling of TiN-based plasmonic metasurface absorbers

We numerically investigate plasmonic metasurface absorbers based on hollow square, hollow cylindrical, and conical nanoantenna geometries fabricated from various plasmonic materials, with emphasis on titanium nitride (TiN) as a refractory alternative to noble metals. Full-wave finite-element simulations in the visible range reveal geometry- and material-dependent absorption behavior, where TiN designs exhibit strong broadband absorption and reduced sensitivity to geometrical variations within the studied parameter space. Fitted analytical models are developed to describe the dependence of wavelength-averaged absorption (400-800 nm) on key structural parameters, enabling reliable performance prediction and efficient optimization. The results show that the intrinsic optical losses and damping properties of TiN support broadband absorption and fabrication tolerance for the examined geometries. This work provides a quantitatively supported framework for designing optimized plasmonic metasurface absorbers for applications such as solar energy harvesting, optical sensing, photothermal conversion, and radiative thermal management.