Resonant scattering of light from a glass/Ag/MgF₂/air system with rough interfaces and supporting guided modes in attenuated total reflection

We report experimental results of the resonant scattering of light from a prism-glass/Ag/MgF₂/air system with use of the attenuated total reflection technique for p and s polarized light. Two MgF₂ film thicknesses were used. The system with the thinner dielectric layer supports two transverse magnetic (TM) and two transverse electric (TE) guided modes at a wavelength of 632.8 nm, and the system with the thicker dielectric layer supports three TM and three TE guided modes. In both cases we found dips in the specular reflection as a function of incident angle that is due to excitation of guided modes in the MgF₂ film. The scattered light shows peaks at angles corresponding to the measured excitation of the guided modes. These peaks are due to single-order scattering and occur for any angle of the incident light. All features in the scattering response are enhanced in resonance conditions, and the efficiency of injecting light into the guide is reduced.