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approved1_page_abstract_shg_antenna_osi__15___finazzi.pdf2015-03-27 09:56:21Marco Finazzi


Author: Marco Finazzi
Requested Type: Pre-Selected Invited
Submitted: 2015-03-12 10:13:47

Co-authors: M.Celebrano, X.Wu, M.Baselli, S.Großmann, P.Biagioni, A. Locatelli, C.De Angelis, G.Cerullo,R.Osellame, B.Hecht, L.Duò, F.Ciccacci

Contact Info:
Politecnico di Milano
Piazza Leonardo da Vinci, 32
Milan, Milan   20133

Abstract Text:
Second Harmonic Generation (SHG) is well known to be a powerful imaging tool for background-free and non-damaging live tissues investigation. Field enhancements in plasmonic nanostructures are often exploited to effectively compensate for the lack of phase-matching in confined volumes with the aim of obtaining brighter nanoscale nonlinear probes. Recently, nanoantenna designs featuring a double resonance at both the excitation and the emission wavelengths have been proposed to improve SHG [1]. However, the high degree of symmetry in plasmonic materials at the atomic scale and in nanoantenna designs have so far poor SHG efficiency [2]. We have circumvented these limitations and engineered gold single-crystalline nanoantennas working in the near-infrared that show unprecedented SHG efficiency thanks to (i) a multi-resonant response occurring at both the excitation and SH wavelength, (ii) a significant spatial overlap of the localized fields at the wavelengths of interest and (iii) a broken-symmetry geometry to achieve dipole-allowed SHG. The effective combination of these key features in a single plasmonic antenna, characterized by the absence of local defects, allows optimizing SHG efficiency in a well-controlled fashion.

[1] K. Thyagarajan et al., Opt. Express 20, 12860 (2012).
[2] M. Finazzi et al., Phys. Rev. B 76, 125414 (2007).