Multi-narrowband absorber based on subwavelength grating structure

A near-infrared multi-narrowband absorber based on subwavelength metal-dielectric-metal grating structure was devised. The relationship between the parameters and the absorption performance was studied. By optimizing the geometrical parameters, a triple narrowband absorber with about 30-nm bandwidth was obtained. The electric and magnetic field distributions of the structure at the peak wavelength helped explain the nature of multi-narrowband absorption, which can be attributed to surface plasmon resonance and Fabry-Pérot resonance. The thickness of dielectric layer determines the absorption bands of the structure mostly due to Fabry-Pérot resonance. In addition, the absorber presents a satisfactory angular insensitive performance within 5° and can meet the demands for many applications.