Anomalous dips in reflection spectra of optical polymers deposited on plasmonic metals

Abstract We have studied reflection spectra of dye-doped and undoped polymers deposited onto Ag Au substrates found anomalous dips in the UV spectral range. On top substrates, ? ? 375 nm were observed PMMA, PVP, PS as well PMMA doped with Rh590 HITC laser dyes. In silver-based samples, positions close to singularities refractive indexes surface plasmon polaritons (SPPs) propagating at interface between polymer. The latter can tentatively explain dips, if scattering polymeric films is large enough launch SPP without any prism or grating. Rh590:PMMA HITC:PMMA on Au, more pronounced than those Ag, broader, shifted shorter wavelengths, their had standard deviations. Furthermore, no gold-based samples polymers, a modest singularity index, predicted theoretically 500 nm, cannot experimentally. It appears likely that origin different from substrates.