Ultraviolet narrowband all-dielectric metasurface absorber with an ultra-thin absorption layer

Ultraviolet (UV, 200-400 nm) detection with high efficiency and excellent spectral resolution is essential in spectral analysis. This Letter proposes a UV narrowband all-dielectric metasurface absorber with an ultra-thin absorption layer. The design incorporates lossless Al₂O₃ resonators placed on a thin (20 nm) lossy Ga₂O₃ film, which enhances the absorption intensity at a specific wavelength. The near-perfect narrowband absorption enhancement results from the spectral overlap of the magnetic dipole (MD) and the electric dipole (ED) absorption modes by surface lattice resonance (SLR). The proposed absorber exhibits high-efficiency and high-quality (Q) absorption performance (A > 95%, Q ∼ 231) and allows for flexible control over the absorption wavelength through simple parameter adjustments. These features make it ideal for narrowband emission, spectrum detection, and multispectral sensing.