Analysis of Resonance Absorption in Multilayered Thin-Film Bi-Grating

Abstract

The resonance absorption of a multilayered bi-grating which consists of thin-film corrugated periodically in two directions is investigated. The absorption in a multilayered thin-film bi-grating has been of considerable interest since we can expect more complex behaviors in the absorption phenomen by virtue of the presence of double periodicity and multilayer structure. In solving the problem, we employed a computational technique based on modal expansion. Taking a sandwiched structure /Ag/SiO 2 /Ag/ for an example, we observed: 1) excitation of a single-interface surface plasmon mode at the lit surface of the 1 st Ag layer with strong field enhancement for thick enough Ag layer case; 2) excitation of coupled short-range or long-range surface plasmon modes at each surface between vacuum and Ag layers with strong field enhancements for thin enough Ag layer cases no matter with the thickness of SiO 2 layers; 3) enhancements of field at surfaces between Ag and SiO 2 layers in some cases related with the thickness of SiO 2 layers. The coupled plasmon modes were resulted by the resonance waves on four surfaces in these cases.