Mid-infrared narrowband spectral modulation based on metal–dielectric hybrid metasurfaces

Abstract

The mid-infrared spectrum (2–10 μm), serving as the molecular vibrational fingerprint region, holds irreplaceable value in gas detection, biosensing, and astronomical observations. This study proposes a novel metal–dielectric hybrid nanodisk metasurface architecture, enabling precise narrowband spectral modulation in the mid-infrared range through controlled stacking of low-loss metallic and high-transparency dielectric materials. The design synergizes the advantages of two-dimensional single-step lithographic integration with spectral tunability, where optical responses originate from near-field coupling effects between localized surface plasmon resonances (LSPRs) and Mie resonances at three-dimensional dielectric interfaces. Numerical simulations demonstrate five discrete spectral channels of the metasurface, featuring a minimal FWHM of 0.173 μm. The spectral sensing sensitivity is calculated as S = 1750 nm/RIU by modulating the environmental refractive index. Additionally, this metasurface exhibits an incident angle robustness of up to 32.5°, effectively addressing the dependency of conventional solutions on light sources. Finally, we discuss the challenges and issues in hybrid metasurface fabrication, providing insights for scalable conformal manufacturing.