Multispectral perfect absorbers using plasmonically induced interference

摘要

Through numerical and theoretical investigations of plasmonically induced interference, we obtain multispectral metamaterial absorbers based on a periodic sub-wavelength array of nanogrooves side-coupled to nanorings. Finite-difference time-domain simulations indicate that a classical three level system forms upon introducing a dark-mode nanoring into the narrow-band perfect absorber consisting of a periodic nanogroove array, thereby leading to dual-band near-unity absorption. Numerical results are consistent with the predictions of coupled-mode theory. Slow light occurs, accompanied by extensive destructive interference in the reflection window. In particular, multispectral absorption occurs only upon introducing multiple sub-dark modes, and the absorber exhibits outstanding absorption stability over a wide range of incident angles. Thus, plasmonically induced interference may offer a new way to obtain multiband absorbers. These results should be useful for multichannel optical filtering and slow-light devices. Published by AIP Publishing.