META 2021, META'12

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Bottom-up magnetoplasmonics and ultracompact standalone nanoantennas in the visible
Alexandre Dmitriev

Last modified: 2011-12-05


I will discuss the advances in bottom-up nanofabrication with hole-mask colloidal lithography (HCL) for nanoplasmonics. HCL is a truly versatile bottom-up nanofabrication of low-dimensional structures at surfaces in ambient conditions. The key is that the method is simple enough, affordable, and can bring benefits in a plethora of research and technology areas, where one needs objects of 20-5000 nm, fabricated on an arbitrary surface and covering cm2 area.1

Two recent examples are magnetoplasmonics and nanoantennas. The brand new and rapidly developing field of magnetoplasmonics explores the mutual relation between magnetization and localized plasmons. Differently from the studies of propagating surface plasmons in ferromagnetic systems or the combination of plasmonic and ferromagnetic materials, our research explores the opportunities arising from the direct excitation of localized surface plasmons in purely ferromagnetic nanostructures. I’ll show that new fundamental property exists in nanoscopic metallic ferromagnets – the localized plasmon resonances and the intrinsic magneto-optical activity combined bring forward the ability of this nanostructures to sensitively control the rotation of the polarization of the scattered light with the applied magnetic field. Essentially, it is an extension of the magneto-optical Kerr effect (i.e., the magnetic field-induced variation of the polarization of the light reflected by a ferromagnetic surface). We, in fact, uncovered a magnetoplasmonic Kerr effect – where the polarization of the reflected light is defined by both magneto-optical coupling and simultaneous excitation of localized surface plasmons in the material (Fig. A – Magneto-optical Kerr effect (MOKE) p-configuration (top) and experiment (bottom), showing the tuning possibility of Kerr rotation by the surrounding refractive index via plasmonic excitations in nanoferromagnets).2

The purpose of an optical antenna is to convert light into localized energy and vice versa. Considerable efforts in optical antennas design focused on utilizing concepts from radio frequency regime. We bring forward the optical nanoantenna that steps beyond low frequency designs and delivers remarkably high directionality operating with the free-space-propagating visible light and having a sub-250 nanometers footprint in all three dimensions. We demonstrate bottom-up approach to fabricate macroscopic arrays of such ultracompact, fully articulated three-dimensional optical nanoantennas and present the way to straightforwardly address the functionality of their elements. The ease and accessibility of this nanoantenna design prompts its use as an affordable test bed for concepts in nano-optics and further suggests applications in the actual nanophotonics devices (Fig. B – array of bottom-up stand-alone 3-elements nanoantennas for the visible light).



2 J. Chen et al., Small 7, 2341 (2011); V. Bonanni et al., Nano Lett., (2011).



nanoplasmonics, magnetoplasmonics, optical nanoantennas, bottom-up