Second Harmonic Generation from Uniaxial Plasmonic Metamaterials: from Elliptical to Hyperbolic Dispersion Regimes

Giuseppe Marino Department of Physics, King's College London, London, UK Paulina Segovia Department of Physics, King's College London, London, UK Alexey V. Krasavin Department of Physics, King's College London, London, UK Pavel Ginzburg Department of Physics, King's College London, London, UK Mahzar E. Nasir Department of Physics, King's College London, London, UK Wayne Dickson Department of Physics, King's College London, London, UK Nicolas Olivier Department of Physics, King's College London, London, UK Grégory Wurtz Department of Physics, King's College London, London, UK Anatoly Zayats Department of Physics, King's College London, London, UK

Second Harmonic Generation (SHG) was the first nonlinear optical effect to be observed once lasers became available [1]. Since, SHG has been studied in various materials and geometries including noble metal surfaces and films. In the latter surface plasmon polaritons have primarily been used to enhance SHG. Recently, SHG in noble metal nanostructures has seen increased scrutiny [2,3] due to the unique optical properties offered by both localized surface plasmons and their hybridization in complex nanostructured systems. However, the rational study of complex structures requires the development of suitable theoretical approaches and numerical tools [4].

We have developed a numerical model to study SHG at the nanoscale and applied it to study gold nanorod-based plasmonic metamaterials. The metamaterial shows an Epsilon Near Zero (ENZ) frequency tunable across the visible and near-IR frequency range, responsible for the emergence of a set of resonances in its vicinity, enabling a multi-resonant coherent response both at the fundamental (FF) and harmonic frequencies (HF). This property allow the achievement of high SHG conversion efficiency and tailored SHG emission. The SHG response of the metamaterial is investigated and discussed based on the modal properties with a particular focus made on the relationship between their near and far-field response, spatial field overlap between FF and HF, and geometry-allowed SH emission.

[1] P.A. Franken, A.E. Hill, C.W. Peters, and G. Weinreich, Phys Rev. Lett. 7, 118 (1961)

[2] G. A. Wurtz, R. Pollard, W. Hendren, G.P. Wiederrecht, D.J. Gosztola, V.A. Podolskiy, and A.V. Zayats, Nature Nanotech. 6, 107-111 (2011)

[3] P. Gingzburg, A. Krasavin, Y. Sonnefraud, A. Murphy, R.J. Pollard, S.A. Maier, and A.V.Zayats, Phys Rev. B, 86, 085422 (2012)

[4] P. Ginzburg, A. V. Krasavin, Gregory A.Wurtz, and A.V. Zayats, arXiv preprint arXiv:1405.4903 (2014).

alexey.krasavin@kcl.ac.uk