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Plasmon surface polariton dispersion by direct optical observation
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1980
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Optical MaterialsEngineeringOptical CoatingsSurface-enhanced Raman ScatteringMetasurfacesMetamaterialsPlasmon Surface PolaritonsDirect Optical ObservationDispersion CurveOptical CharacterizationElectromagnetic MetamaterialsPolariton DynamicOptical PropertiesOptical SystemsReflectanceNanophotonicsPlasmonic MaterialMaterials SciencePhotonicsPhysicsOptical ComponentsOptical SensorsDepth-graded Multilayer CoatingPlasmonicsApplied PhysicsLangmuir WedgeNanofabrication
The study presents simple optical methods to directly visualize the plasmon surface polariton dispersion curve and its shift due to overcoatings of varying thickness. Using a collimated white‑light beam dispersed by a prism and focused onto a metal‑film–coated prism, the attenuated total reflection spectrum is spatially resolved, and a Langmuir wedge demonstrates the dispersion shift for different coating thicknesses. The technique proves that plasmon surface polaritons can monitor nanometer‑scale coating thicknesses.
Simple optical techniques are described for the direct visual observation of the plasmon surface polariton dispersion curve, ω vs κ, and of the shift in the dispersion curve from overcoatings of different thicknesses. To see the dispersion curve, a collimated beam of white light is dispersed by a prism, and then focused by a cylindrical lens onto the base of a second prism coated with a thin metal film. With this arrangement the attenuated total reflection spectrum is obtained with all the visible frequencies spatially resolved. The shift of the dispersion curve for coatings of different thicknesses is illustrated in a separate experiment using a specially constructed Langmuir wedge. This demonstrates the usefulness of plasmon surface polaritons for monitoring coatings with thicknesses of the order of nanometers.