Hyperbolic metamaterial antenna for second- harmonic generation tomography Paulina Segovia,1,2,5 Giuseppe Marino,1,5 Alexey V. Krasavin,1,5 Nicolas Olivier,1 Gregory A. Wurtz,1,3 Pavel A. Belov,4 Pavel Ginzburg,1,2,* and Anatoly V. Zayats1 1Department of Physics, King’s College London, Strand, London WC2R 2LS, UK 2Currently with the School of Electrical Engineering, Tel Aviv University, Tel Aviv 69978, Israel 3Currently with the Department of Physics, University of North Florida, Jacksonville Florida 32224, USA 4National Research University of Information Technologies, Mechanics and Optics (ITMO), St. Petersburg 197101, Russia 5Contributed equally * [email protected] Abstract: The detection and processing of information carried by evanescent field components are key elements for subwavelength optical microscopy as well as single molecule sensing applications. 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Scalora, “Role of antenna modes and field enhancement in second harmonic generation from dipole nanoantennas,” Opt. Express 23(2), 1715– 1729 (2015). 34. C. Forestiere, G. Iadarola, G. Rubinacci, A. Tamburrino, L. Dal Negro, and G. Miano, “Surface integral formulations for the design of plasmonic nanostructures,” J. Opt. Soc. Am. A 29(11), 2314–2327 (2012). 1. Introduction A key challenge in microscopy is spatial resolution, mediating the relation between real features of an object and its observed image. In optical microscopy, a complete set of electromagnetic modes including the evanescent ones is required to reconstruct a perfect image. Evanescent modes, however, decay in the vicinity of the object before being detected in the far-field, giving rise to the diffraction limit [1]. Among various approaches for resolution improvement [2], the use of nanostructured composites (metamaterials) is beneficial, enabling efficient manipulation of evanescent fields components in order to reconstruct the image of an object with the resolution limited only by a particular realization of the metamaterial, e.g., its inherent material losses [3]. While superlenses [4] do not change the decaying nature of evanescent components, lenses made with materials exhibiting hyperbolic dispersion (hyperlenses) [5,6] convert them in propagating modes detectable in the far-field. This near-to-far field transformation is enabled by the hyperbolic dispersion of the medium which occurs in uniaxial crystals with different signs of the longitudinal and transverse components of the permittivity tensor [7]. Such dispersion also gives rise to #249227 Received 2 Sep 2015; revised 22 Oct 2015; accepted 27 Oct 2015; published 17 Nov 2015 (C) 2015 OSA 30 Nov 2015 | Vol. 23, No. 24 | DOI:10.1364/OE.23.030730 | OPTICS EXPRESS 30731 enhanced spontaneous decay rates of nearby emitters [8–10]. Hyperbolic metamaterials can be based on, e.g., arrays of vertically aligned nanorods [11] or layered metal-dielectric structures [8]. They have already been used to demonstrate improved resolution in linear optical microscopy [12–14]. These microscopy techniques,