Tailoring infrared thermal absorption through hybrid resonances in anisotropic-medium-contained nanostructures

Tailoring infrared thermal radiation via nanostructures holds significant promise for next-generation optoelectronic applications ranging from hyperspectral detection to adaptive camouflage. However, achieving precise spectral-selective absorption at multiple discrete wavelengths or across different wave ranges remains a fundamental challenge in nanophotonics. Herein, we demonstrate a hybrid nanostructured architecture comprising a gold-substrate-backed silicon layer and anisotropic nanostructures atop it for tailoring infrared thermal radiation. The anisotropic materials include hexagonal boron nitride (hBN) and α -phase molybdenum trioxide ( α -MoO 3 ), and the nanostructures include films, disk arrays, and pyramids. Case studies reveal that the synergistic interplay of different resonances – Fabry-Pérot resonance, hyperbolic phonon polaritons, and the Mie-type mode – enables tailorable infrared absorption. Results indicate the proposed structure achieves significantly narrowband enhanced absorption with an absorptivity of 0.968 and a Q -factor up to 176.1. It can also achieve enhanced absorption across a broad wavelength range of 2 μm, paving the way for advanced infrared systems that incorporate spectral signature control and on-demand emissivity engineering.