Optical antennas: A boost for infrared detection

Abstract

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Single sub-wavelength aperture with greatly enhanced transmission

“…Somewhat better T were reported for various ridge-type apertures [4,5]. Among them, the best T were predicted and measured for bow-tie geometries [6][7][8]. From computational works, the scattering light spot was highly localized in the gap between the bowtie tips with maximum normalized electric field, E, intensities, |E| 2 /|E 0 | 2 , reached up to 10 4 for optimal reported geometry and illumination conditions [7,8].…”

“…However, over the last decade, enhanced optical transmissions have been actually reported for modified sub-wavelength holes. Typically, such modifications involved the introduction of the scattering centres inside a single aperture ( [2][3][4]; [5] and references therein; [6][7][8]) or dealt with the surroundings of the aperture by periodic corrugation in the screen ( [9][10][11][12][13]; [14] and references therein; [15][16][17]). For example, a strong scattering intensity, I s , of incident field, I 0 , at particular λ is expected from Mie theory [18] by placing metal particles with negative dielectric constant ε m and radius r p inside the aperture with positive dielectric constant, d , i.e.…”

“…Among them, the best T were predicted and measured for bow-tie geometries [6][7][8]. From computational works, the scattering light spot was highly localized in the gap between the bowtie tips with maximum normalized electric field, E, intensities, |E| 2 /|E 0 | 2 , reached up to 10 4 for optimal reported geometry and illumination conditions [7,8]. Theoretically, the |E| 2 /|E 0 | 2 enhancements could be even larger for smaller tip gaps, higher tip sharpness and larger antenna arm to tip gap length ratios.…”