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Full-Text Articles in Physics
Determination Of The Goos-Hänchen Shift In Dielectric Waveguides Via Photo Emission Electron Microscopy In The Visible Spectrum, Theodore Stedmark, Robert Campbell Word, Rolf Kӧnenkamp
Determination Of The Goos-Hänchen Shift In Dielectric Waveguides Via Photo Emission Electron Microscopy In The Visible Spectrum, Theodore Stedmark, Robert Campbell Word, Rolf Kӧnenkamp
Physics Faculty Publications and Presentations
Photoemission Electron Microscopy (PEEM) is a versatile tool that relies on the photoelectric effect to produce high-resolution images. Pulse lasers allow for multi-photon PEEM where multiple photons are required excite a single electron. This non-linear process can directly image the near field region of electromagnetic fields in materials. We use this ability here to analyze wave propagation in a linear dielectric waveguide with wavelengths of 410nm and 780nm. The propagation constant of the waveguide can be extracted from the interference pattern created by the coupled and incident light and shows distinct polarization dependence. The electromagnetic field interaction at the boundaries …
Subwavelength Visualization Of Light In Thin Film Waveguides With Photoelectrons, Joseph P. Fitzgerald, Robert Campbell Word, Rolf Könenkamp
Subwavelength Visualization Of Light In Thin Film Waveguides With Photoelectrons, Joseph P. Fitzgerald, Robert Campbell Word, Rolf Könenkamp
Physics Faculty Publications and Presentations
We report the visualization and quantitative analysis of electromagnetic surface fields at solid surfaces with the potential for λ/50 resolution. To illustrate this capability, we investigate patterns in two-photon photoemission images of light-diffracting structures in waveguiding, transparent thin films. The obtained micrographs show interference patterns between incident and guided light with a remarkable sensitivity to subwavelength features. We demonstrate that photoemission rates are directly related to the surface field strengths and develop a subwavelength method to calculate the surface fields from optical properties and surface topology based on the two-dimensional Kirchhoff diffraction integral. Calculated images based on this theoretical approach …
Direct Coupling Of Photonic Modes And Surface Plasmon Polaritons Observed In 2-Photon Peem, Robert Campbell Word, Joseph Fitzgerald, Rolf Könenkamp
Direct Coupling Of Photonic Modes And Surface Plasmon Polaritons Observed In 2-Photon Peem, Robert Campbell Word, Joseph Fitzgerald, Rolf Könenkamp
Physics Faculty Publications and Presentations
We report the direct microscopic observation of optical energy transfer from guided photonic modes in an indium tin oxide (ITO) thin film to surface plasmon polaritons (SPP) at the surfaces of a single crystalline gold platelet. The photonic and SPP modes appear as an interference pattern in the photoelectron emission yield across the surface of the specimen. We explore the momentum match between the photonic and SPP modes in terms of simple waveguide theory and the three-layer slab model for bound SPP modes of thin metal films. We show that because the gold is thin (30- 40 nm), two SPP …
Photoelectron Emission Control With Polarized Light In Plasmonic Metal Random Structures, Robert Campbell Word, Joseph Fitzgerald, Rolf Kӧnenkamp
Photoelectron Emission Control With Polarized Light In Plasmonic Metal Random Structures, Robert Campbell Word, Joseph Fitzgerald, Rolf Kӧnenkamp
Physics Faculty Publications and Presentations
The authors report on the possibility of switching the emission rate of photoelectrons by polarization changes in the plasmon excitation light. Photoelectron emission is strongly enhanced in the near-field of localized surface plasmons and occurs from areas with typical diameters of 20-70 nm. The underlying physical process involves excitation of a localized surface plasmon polariton with a femtosecond laser pulse, and a subsequent multi-photon photoemission process. The non-linearity of this process leads to a sharp polarization dependence that allows efficient switching of the emission. We demonstrate that a 90° polarization change can result in on/off ratios of ∼100 for electron …
Photoemission From Localized Surface Plasmons In Fractal Metal Nanostructures, Robert Campbell Word, Rolf Könenkamp, T. T. Dornan
Photoemission From Localized Surface Plasmons In Fractal Metal Nanostructures, Robert Campbell Word, Rolf Könenkamp, T. T. Dornan
Physics Faculty Publications and Presentations
We use photoemission microscopy to characterize localized surface plasmon distributions in nanostructured gold layers on indium-tin-oxide/glass substrates. The Au films have a fractal dimension of ∼1.3 and smallest feature sizes of ∼100 nm. We use femtosecond laser pulses at a wavelength of ∼800 nm for the plasmon excitation. Photoelectron emission occurs by a three-photon process in localized areas of indium-tin-oxide with ∼70 nm diameter. In these areas the photoemission rate is enhanced several thousand fold compared to nonstructured surface areas. The results show that plasmon enhanced photoemission can be induced in a nonabsorbing material in proximity to a plasmon-active metal …
Image Properties In An Aberration-Corrected Photoemission Electron Microscope, Rolf Könenkamp, T. Jones, J. Elstner, Robert Campbell Word, Gertrude Rempfer, Todd Dixon, Luis Almaraz, Walter P. Skoczylas
Image Properties In An Aberration-Corrected Photoemission Electron Microscope, Rolf Könenkamp, T. Jones, J. Elstner, Robert Campbell Word, Gertrude Rempfer, Todd Dixon, Luis Almaraz, Walter P. Skoczylas
Physics Faculty Publications and Presentations
We report recent progress in the construction of a new aberration-corrected photoemission electron microscope. The correcting element in this instrument is a hyperbolic electron mirror which corrects for chromatic and spherical aberration. We present first images obtained with the new instrument and numerical results from trajectory and wave-optical calculations indicating that the resolution can be of the order of 1 nm.