Ultra-narrow-band perfect absorber based on high-order plasmonic resonance in metamaterial
Abstract
We demonstrate an, ultra-narrow-band perfect absorber based on high-order magnetic plasmonic resonance, which is polarization independent because of the ring element in the structure. When the thickness tt of MgF2 is 60nm, the absorption at frequency 424.5THz is close to 1, its full width at half maximum (FWHM) is 13nm. In our structure, a wavelength sensitivity about 190nm/RIU is achieved by utilizing the absorption peaks alter upon the refractive index change. In addition, we also discuss the figure of merit (FOM*) under different reflective index of sample surface. Therefore, the ultra-narrow-band perfect absorber will provide the great potential applications to filters and plasmonic refractive index sensors.