Chen KR, Chu WH, Fang HC, Liu CP, Huang CH, Chui HC, Chuang CH, Lo YL, Lin CY, Hwung HH, Fuh AYG. Beyond-limit light focusing in the intermediate zone.
Opt Lett 2011;
36:4497-4499. [PMID:
22139221 DOI:
10.1364/ol.36.004497]
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Abstract
We experimentally verify that a new nanolens of a designed plasmonic aperture can focus visible light to a single line with its width smaller than the limit of half the wavelength in the intermediate zone. The experimental measurement indicates that while the near field plays a role to increase the spot size in the near zone, it is negligible at the beyond-limit focused region; i.e., the focused light is dominated by the radiative fields. The image taken by the optical microscope shows that the fields focused have propagated to the far zone. Besides being of academic interest, the nanolens capable in achieving a lower diffraction limit in the intermediate zone is important for application possibilities.
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