Broadband Interferenceless Perfect Absorption in Hexagonal Boron Nitride and Lithium Fluoride Hyperbolic Metamaterial

Abstract

Interferenceless perfect absorption holds significant promise for applications in photodetection, photovoltaics, and medical diagnostics. In this study, an effective composite metamaterial with nanoscale thickness, composed of hexagonal Boron nitride (hBN) and lithium fluoride (LiF) layers is presented. Using effective medium approximation theory, the proposed design achieves broadband interferenceless perfect absorption, independent of polarization, either transverse magnetic or transverse electric. The structure employs a noninterferometric approach, enabling near-zero reflectance over a wide incident angle (${\theta }_i=0°–80°$). Notably, by adjusting the relative layer thicknesses, the hBN–LiF composite structure offers substantial control over its absorption characteristics. The absorption frequency can be blue-shifted by increasing the hBN thickness or red-shifted by increasing the LiF thickness. This flexible tunability makes the structure an ideal candidate for photodetection, infrared sensing, and other light-manipulation technologies.