Controlling absorption resonances from sub-wavelength cylinder arrays

The absorption and extinction spectra of sub-wavelength cylinder arrays are shown to present two different kind of resonances. Close to the Rayleigh anomalies, the diffractive coupling with the lattice periodicity leads to sharp peaks in the extinction spectra with characteristic Fano line shapes for both s and p-polarizations. When the material exhibits an absorption line or in the presence of localized surface plasmon/polaritons, the system is shown to present resonant absorption with wider and symmetric line shapes. For s-polarization our analysis predicts a theoretical limit of 50 % of absorption. Interestingly, for p-polarized light and an appropriate choice of parameters, subwavelength cylinder arrays can present perfect (100 %) absorption.