Hydrodynamic Model for Nonlinear Plasmonics: From Harmonic Generations to Coherent Supercontinuum

Alexey V. Krasavin Department of Physics, King's College London, London, UK Pavel Ginzburg Department of Physics, King's College London, London, UK Centre for Nanophotonics and Metamaterials, ITMO University, Saint Petersburg, Russia Paulina Segovia 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

The electromagnetic response of a free-electron gas leads to the inherent nonlinear optical behaviour of nanostructured plasmonic materials enabled through both strong local field enhancements and complex collective electron dynamics.1 In this presentation, we will report our very recent results on time-domain implementation of the hydrodynamic model for conduction electrons in metals which enables non-perturbative studies of nonlinear coherent interactions between light and plasmonic nanostructures.2,3 The effects originating from the convective acceleration, the magnetic contribution of the Lorenz force, the quantum electron pressure, as well as the presence of the nanostructure’s boundaries are taken into account leading to the appearance of second, third and higher harmonics in the scattering field of a metallic nanorod (Fig. 1).2 It will be shown that frequently used approximated models should be reconsidered. Furthermore, we will also report supercontinuum generation in resonantly-tuned metallic nanospirals originating from the nonlocal effects.3 The proposed time-domain method enables one to obtain a universal, self-consistent numerical solution free from any approximations, enabling investigations of nonlinear optical interactions with arbitrary shaped optical pulses, in contrast to the generally employed plane-wave CW pump assumption, opening unique opportunities to approach realistic experimental scenarios.

Fig. 1. Comparison of SHG and THG scattering fieldmaps obtained using hydrodynamic and phenomenological effective models.

[1]. M. Kauranen and A. V. Zayats, Nature Phot. 6, 737 (2012).

[2]. P. Ginzburg, A. V. Krasavin, G. A. Wurtz, and A. V. Zayats, ACS Photonics, DOI: 10.1021/ph500362y (2014).

[3]. P. Ginzburg, A. V. Krasavin, G. A. Wurtz, and A. V. Zayats, to be published.

alexey.krasavin@kcl.ac.uk









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