Near-infrared perfect absorption achieved with graphene-LiF multilayer metamaterial.

Achieving perfect absorption of electromagnetic radiation across the near-infrared (NIR) to short-wave infrared spectrum is critical for various applications. While previous studies have demonstrated tunable absorption in graphene-based systems, few designs have achieved a polarization-insensitive and broadband response with dual electrical and structural tunability. Here, we present a graphene-lithium fluoride (LiF) multilayer heterostructure that achieves perfect absorption within the NIR wavelength range. By leveraging the gate-tunable conductivity of graphene in combination with the low-loss properties of LiF, our design enables broadband absorption through critical coupling and plasmonic modes. Our results demonstrate perfect absorption for both transverse magnetic (TM) and transverse electric (TE) polarizations across various incident angles. With an increasing number of graphene layers (GLs), the bandwidth of the absorption spectra broadens, and a blueshift occurs in the spectrum. This dual tunability positions the proposed graphene-LiF metamaterial as a versatile platform for dynamic control over optical responses in NIR applications.