Resonantly enhanced transmission of light through subwavelength apertures with dielectric filling |
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Authors: | Huizhong Xu |
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Institution: | School of Applied and Engineering Physics, Cornell University, 223 Clark Hall, Ithaca, NY 14853, USA |
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Abstract: | Using both analytical and numerical methods to study transmission of light through dielectric-filled subwavelength apertures in a real metal, we have found that a propagating mode can in principle exist inside a waveguide of arbitrary small size if a particular relationship between the dielectric constants of the cladding and filling materials at the incident frequency is satisfied. Practical transmission through a subwavelength aperture of finite depth can be enhanced when the depth is such that Fabry-Pérot-like resonances are excited. For 810 nm light incident on a silicon-filled 50-nm-diameter aperture in a 200-nm-thick gold film, we found that a normalized near-field intensity ratio of 1.6 at the exit can be achieved. This resonantly enhanced transmission phenomenon may be advantageously applicable to near-field scanning optical microscopy and single-molecule spectroscopy. |
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Keywords: | Apertures Diffraction Near-field scanning optical microscopy Surface plasmon polaritons |
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