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Scanning near-field optical microscopy study of metallic square hole array nanostructures
We fabricate periodic arrays of simple-square and composite-square air hole nanostructures on a 120 nm thick Au film deposited on glass substrate by focused ion beam technology and study their optical properties by examining the optical near-field distribution via scanning near-field optical microsc...
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Published in: | Journal of applied physics 2008-12, Vol.104 (11), p.114303-114303-10 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | We fabricate periodic arrays of simple-square and composite-square air hole nanostructures on a 120 nm thick Au film deposited on glass substrate by focused ion beam technology and study their optical properties by examining the optical near-field distribution via scanning near-field optical microscopy in the near-infrared region. The simple-square nanostructure only contains one square air hole in each unit cell, while the composite-square one contains the same size square air hole in the center and eight smaller square air holes in the periphery. The measured optical near-field patterns for the two nanostructures show very different distribution features. High intensity light spots locate within the central square air hole in the simple-square structure, while they sit at the peripheral smaller square air holes in the composite-square structure. Numerical simulations based on the plane-wave transfer-matrix method have been carried out to analyze the optical near-field patterns for the two metallic nanostructures and agree well with the experimental data. The results indicate that light interaction with metallic nanostructures is very sensitive to even a small change in the subtle geometrical feature. Meanwhile, by comparing near-field patterns with dielectric nanostructures theoretically, we also find that optical confinement is better for gold nanostructures than for dielectric nanostructures. |
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ISSN: | 0021-8979 1089-7550 |
DOI: | 10.1063/1.3032902 |