Surface polaritons in a one-sided corrugated thin film composite excited using a coupler-prism: linear perturbation approach

Abstract

A merge of the experimental methods of attenuated total reflection (ATR) and grating-coupling (GC) yields a very versatile single tool for the study of elementary crystal surface excitations. In this study, a theoretical account of the combined method of ATR and GC (ATRGC) for probing surface polaritons in a thin film composite is given. The basic ATR experimental set-up is considered but with the additional feature that a classical grating of shallow grooves is deposited on only one of the interfaces of the thin film specimen. The main results of the investigations undertaken here are the first-order reflectivities, which in fact arise due to the presence of a grating. The thin film specimen consists of spherical metallic grains systematically embedded in a host medium, both constituents being surface-active. The dispersion curves of these modes are found to be elevated to higher frequencies as the fractional volume content of the grain constituents, the so-called filling factor, is increased. Surface polariton structures occurring in a reflectivity spectrum are therefore expected to shift to higher frequencies as a direct consequence of increasing the filling factor.