Autor/a:
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Flauraud, Valentin; Regmi, Raju; Winkler, Pamina Martina; Alexander, Duncan T. L.; Rigneault, Herve; Hulst, Niek F. van; Garcia-Parajo, Maria F.; Wenger, Jerome; Brugger, Juergen
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Abstract:
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Optical nanoantennas have a great potential for enhancing light-matter interactions at the
nanometer scale, yet fabrication accuracy and lack of scalability currently limit ultimate
antenna performance and applications. In most designs, the region of maximum field
localization and enhancement (i.e., hotspot) is not readily accessible to the sample since it is
buried into the nanostructure. Moreover, current large-scale fabrication techniques lack
reproducible geometrical control below 20 nm. Here, we describe a new nanofabrication
technique that applies planarization, etch back and template stripping to expose the excitation
hotspot at the surface, providing a major improvement over conventional electron beam
lithography methods. We present large flat surface arrays of in-plane nanoantennas, featuring
gaps as small as 10 nm with sharp edges, excellent reproducibility and full surface
accessibility of the hotspot confined region. The novel fabrication approach drastically
improves the optical performance of plasmonic nanoantennas to yield giant fluorescence
enhancement factors up to 104-105 times, together with nanoscale detection volumes in the 20
zeptoliter range. The method is fully scalable and adaptable to a wide range of antenna
designs. We foresee broad applications by the use of these in-plane antenna geometries
ranging from large-scale ultra-sensitive sensor chips, to microfluidics and live cell membrane
investigations. |