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.