polarization-independent narrowband near-perfect absorption based on one-dimension embedded aluminum grating

In the past, the polarization-insensitive absorption is realized mainly employing the two-dimensional periodic structure of fourfold rotational symmetry, which greatly increases the manufacturing complexity and cost. here, we present the numerical design of a polarization-independent near-perfect absorber incorporating one-dimensional embedded aluminum grating. the absorption peaks near 99% at 520-nm wavelength for different polarization angles are achieved. the underlying mechanism associated with the resonance is attributed to the magnetic polariton resonance and the cavity-mode resonance for tm and te polarization, respectively, and further explained by the inductor-capacitor circuit model and the eigen equation of cavity mode. furthermore, the effects of geometrical parameters of the nano-cavity on the absorption performance are discussed. the proposed structure provide a new way to achieve polarization-independent absorption with one-dimensional meta-surface, which has broad applications in plasmonic sensors, photo-detectors, and so on.