Experimental Investigation of Focusing of Gold Planar Plasmonic Lenses
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To experimentally demonstrate the subwavelength focusing of depth-tuned or non-depth-tuned plasmonic lenses, we first designed this type of lens using diffraction-coupling-angle based method, then fabricated the structure in gold thin film with focused ion beam, and finally characterized its focusing behavior using near-field scanning optical microscope. It is found that this type of lens has a resolution limit on the focal plane due to the field represented by angular spectrum having a cut-off frequency, while at the near field the lens has sub-diffraction limit focusing capability due to the existence of high-angular-frequency components in the field.
KeywordsPlasmonic lens Metallic nanostructure Diffraction and propagation
This work is financially supported by A*STAR (Agency for Science, Technology and Research), Singapore, under SERC Grant No. 072 101 0023.
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