Results 1 - 10 of 6311
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[en] We present a demonstration of the surface plasmon phenomenon as it occurs in thin metal island films. The metal films are deposited on glass microscope slides. The effect of the surface plasmon resonance may be observed visually on the slide without further apparatus. Heating the film changes the shape of the islands and therefore the resonant frequency of the surface plasmon and changes the color of the film. Placing the film in a dielectric medium changes the resonance condition for the surface plasmon again and changes the color again. We show this by coating the slides with commercially available liquids with different indices of refraction. We present a theoretical model that assumes the islands are oblate spheroids. There are enough details given so that the equations can be programed and the theoretical optical absorbance can be reproduced. We also present a modification to the theory so that the shift in resonant frequency can be calculated when the spheroids are immersed in the index fluids. We describe our apparatus for making thin films and our optical spectrometer system. We then present optical absorbance measurements of thin films of both Ag and Au in air and in two liquids with different indices of refraction. (c) 2000 American Association of Physics Teachers
[en] We applied quantum theory for nonlocal response and plasmon-assisted field enhancement near a small metallic nanoscale antenna in the limit of weak incoming fields. A simple asymmetric bio-inspired design of the nanoantenna for polarization-resolved measurement is proposed. The spatial field intensity distribution was calculated for different field frequencies and polarizations. We have shown that the proposed design the antenna allows us to resolve the polarization of incoming photons.
[en] A possibility of transferring of light energy between coupled plasmon waveguide channels is considered. These channels are formed on the basis of a metal-dielectric-metal structure in which the dielectric gap has two closely located minima along the thickness. Dependences of the light energy pumping speed on the minimum gap thickness and distance between channels are found
[en] Full text: Plasmonics is one of the major parts of nano-optics. When light hits a gold nanoparticle which is smaller than the wavelength, it can resonantly excite coherent electron oscillations (localized surface plasmons) with a strong optical near field enhancement. This effect is promising for several applications in sensor technology. The spectral position and strength of localized surface plasmons depends on the shape and the roughness of the nano-particle. We investigate the influence of nanometric surface roughness of gold nano-particles on the optical near fields with the aim to optimize them. We modify the surface roughness by varying the production parameters and by following annealing. Our investigation methods include AFM, SEM and spectrometry. Our results indicate sharper resonance peaks in the absorbance spectrum for smoother surfaces. (author)
[en] The surface plasmons and polaritons in thin flims cut from a uniaxial crystal are discussed. Only two geometries are considered, with the anisotropy axis normal or parallel with the film surface. The dispersion equations are solved in the long wavelength limit and for very large film thickness the known results for semi-infinite medium are recovered
[en] Here, we report a systematic plasmonic study of twisted bilayer graphene (TBLG)—two graphene layers stacked with a twist angle. Through real-space nanoimaging of TBLG single crystals with a wide distribution of twist angles, we find that TBLG supports confined infrared plasmons that are sensitively dependent on the twist angle. At small twist angles, TBLG has a plasmon wavelength comparable to that of single-layer graphene. At larger twist angles, the plasmon wavelength of TBLG increases significantly with apparently lower damping. Further analysis and modeling indicate that the observed twist-angle dependence of TBLG plasmons in the Dirac linear regime is mainly due to the Fermi-velocity renormalization, a direct consequence of interlayer electronic coupling. Our work unveils the tailored plasmonic characteristics of TBLG and deepens our understanding of the intriguing nano-optical physics in novel van der Waals coupled two-dimensional materials.