Numerical Study of a Wide-angle Near-Perfect Absorber for the Visible Regime Incorporating Metal-Dielectric-Metal Subwavelength Grating Structure

A near-perfect absorber for the visible regime based on metal-dielectric-metal subwavelength grating structure with the refractory metals is designed and demonstrated numerically. The absorber presents an average absorption over 98.4% in the visible regime at normal incidence. Angle-relative analysis shows that the proposed structure has good angle-tolerance. The high average absorption (86.6%) in the visible region can be maintained with the incident angles up to 60°. Through the analysis of the magnetic field, the physical origin is verified that this excellent absorption performance mainly stems from the cooperative effect of surface plasmonic resonances and the intrinsic broadband spectral responses by the refractory metals. In addition, the dependence of the absorption spectrum of the proposed absorber on the structural parameters is analyzed. This work provides an idea for the design of high-performance absorbers and has potential applications in advanced light energy capture and integration systems.

Angular Goos-Hanchen shift in subwavelength gratings enhanced by surface plasmon resonance

The angular Goos-Hanchen shift dependence on the subwavelength grating parameters and the incident Gaussian beam width is investigated theoretically. High sensitivity of the angular Goos-Hanchen shift to the incident angle of a light beam near the surface plasmon resonance is demonstrated. Splitting of the reflected beam into two angularly separated beams is shown for strongly focused beam incident at the surface plasmon resonance angle.