Extraordinary Transmission of Light through Al(Ag)/Si Structure Perforated with Periodic and Random Distribution of Holes
| Autor: | Yi-Tsung Chang, 張議聰 |
|---|---|
| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 The main contribution of this thesis is the investigation of the light transmission through a metal/dielectric structure perforated with periodic and random distribution of holes on metallic film. In recent year, the effects of surface electric charge field interacted with the localized surface plasmons under the Bragg scattering condition with the light transmission through a structure of periodic metal holes array are extensively studied. But the transmission peak position of the surface plasmon modes in random structure of holes, the propagation length, dispersion relation, the intrinsic damping and radiation damping of surface plasmon have not yet been investigated in detail. To answer these questions, an aluminum metallic film is evaporated on doubly polished Si substrate, then the hexagonally-ordered holes array, superperiodic micro-cell arrays, random distributed holes and micro-cell arrays on aluminum film are formed by lithography, respectively. The optical transmission properties and dispersion relation of surface plasmon are measured and examined by Fourier Transform Infrared (FTIR) spectrometer. The propagation length and the damping of surface plasmon are calculated and analyzed in details. The dispersion relation of surface plasmon polariton of hexagonally-ordered holes array is measured, it is found that as the light was normally incident onto the sample, the (1,0) Al/Si surface plasmon modes split into two peaks in the transmission spectra, and this effect is most obvious when the diameter of the hole is close to a half of the lattice constant. At larger incident angles, the six degenerate (1,0) Al/Si surface plasmon modes split into three or four modes depending on the symmetry axis, even higher-order surface plasmon modes can be identified for small hole diameters. As to the superperiodic micro-cell arrays, the transmission spectra and dispersion relation of surface plasmon polariton indicated the surface plasmons are generated by Fabry-Perot type waveguide resonances with different integer order. The ratio of periodicity between the super-periodic structure p and the N*N micro-cell d determines the integer order (where N is the number of isolated holes, N= 3, 4 and 5), and suggest that the surface plasmons are Fabry-Perot type resonance within a super unit cell. As to the random distributed holes, the transmission spectra and dispersion relation of surface plasmon polariton suggest that the primary (1,0) Al/Si surface plasmon mode is determined by the nearest neighbor distance in a cluster of random distributed holes, the intensity of transmission peak and the full width at half maximum (FWHM) is determined by the size and number of random distributed holes, and even surface plasmon modes of other distributed distance can be identified as well. When the light incident angle increases, the degenerate surface plasmon mode can not be observed in the dispersion relation, it is owing to the fact that the number of random distributed holes becomes less. As to the micro-cell arrays with random distribution, the transmission spectra and dispersion relation of surface plasmon polariton indicate that as the period of micro-cells is changed, the transmission peaks also changes, it can be exploited to the application of the infrared wavelength-selective devices. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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