The Study On Absorption Property Of Perfect Metamaterial At Optic Frequency Range

Metamaterial is a kind of artificial material,the size of unit cell is less than wavelength of light.Due to the property of metamaterial depend on its periodic construction,is independ on the property of material,metamaterial has lots of extraordinary properties,such as negative refraction,electromagnetically induced transparency,electromagnetically induced absorption,perfect absorber,and so on We research the perfect absorber of metamaterial in this paper.According to the classification of absorbing bandwidth,metamaterial perfect absorbers can be divided into two categories,broad-band absorbers and narrow-band absorbers.And the narrow-band absorbers can also be divided into two categories,single-band absorbers and multiband absorbers.Broadband absorbers can be used for solar cell and photon detector,and so on.Narrow band absorbers can be used for filter and sensor,and so on.In this paper,we achieve a narrow-dual-band perfect absorber based on the electromagnetically-induced transparent(EIT)-like effect.The unit cell of this ab-sorber consist of gold bars in top layer and a dielectric layer.In our scheme,two short gold bars in top layer are excited directly by incident plane wave serving as the bright mode.The middle gold bar can’t be excited by incident light,it is excited by the local electric field of two short gold bars serving as dark mode.According to the strong coupling between the two short gold bars and the middle gold bar,two ab-sorption peaks at 198.47 THz and 209.79 THz,respectively,and the corresponding absorption rates are both over 99%.The quality factor of the two absorption peaks are 41.76(198.47 THz)and 71.42(207.79 THz),respectively,and the narrow-distance of the two absorption peaks is 9.32 THz.Besides,we calculate the sensitivity of two absorption peaks.The sensitivity are 311.5 nm/RIU and 246 nm/RIU,respectively.In this paper,we achieve a ultra-narrow band absorber based on the electro-magnetically induced absorption(EIA)-like effect.The unit cell of this absorber consist of a sliver layer with two slots and a dielectric layer.According to Babi-net’s principle,two resonator slots in top layer are excited by the magnetic field of incident light serving as the bright mode.The strong coupling between the two bright modes result in electromagnetically-induced absorption(EIA)-like effect.The electromagnetically-induced absorption(EIA)-like effect in plasmonic metamaterials usually has a narrow linewidth accompanied with the high absorption rate peak,it has a great potential to be a narrow-band absorber.The absorptivity of ultra-narrow perfect absorber is over 99%,and its Q-factor is 49.6.In addition,we calculate the sensitivity of the absorption peak,it is 204.6 nm/RIU.