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Aluminum nanostructures have recently been at the focus of numerous studies due to their properties including oxidation stability and surface plasmon resonances covering the ultraviolet and visible spectral windows. In this article, we reveal a new facet of this metal relevant for both plasmonics purpose and photo-thermal conversion. The field distribution of high order plasmonic resonances existing in two-dimensional Al structures is studied by nonlinear photoluminescence (nPL) microscopy in a spectral region where electronic interband transitions occur. The polarization sensitivity of the field intensity maps shows that the electric field concentration can be addressed and controlled ondemand. We use a numerical tool based on the Green dyadic method to analyze our results and to simulate the absorbed energy that is locally converted into heat. The polarization-dependent temperature increase of the Al structures is experimentally quantitatively measured, and is in an excellent agreement with theoretical predictions. Our work highlights Al as a promising candidate for designing thermal nanosources integrated in coplanar geometries for thermally assisted nanomanipulation or biophysical applications.Metallic nanostructures sustain localized and delocalized Surface Plasmon (SP) resonances when they are excited under specific conditions. These resonances are giving rise to large enhancement of the electromagnetic field, subwalength confinement, and plasmon propagation in structures with low dimensionalities 1,2 . Owing to their remarkable optical properties, SP resonances have led to a large number of direct applications including high-precision biological sensing 3 , light manipulation by metasurfaces 4 , design of integrated devices for information processing 5 , and highly localized heat sources 6,7 . Due to the large negative real part of the dielectric function in the visible spectrum, gold or silver, either as lithographed patterns or as colloidal nanoparticles, represent the bulk of plasmonic devices so far. Although both metals exhibit complementary features that have fostered the fast development of plasmonics as a technology, these two noble metals also suffer from drawbacks; namely bulk oxidation for silver and an important interband absorption for gold at energies above 2.25 eV. Moreover, both are expensive materials limiting their systematic and massive use in commercial systems. These considerations triggered a rising interest for non-conventional plasmonic materials 8,9 . In this context, while discarded for a long time for plasmonic applications due to its high losses in the red part of the visible spectrum, aluminum has recently demonstrated its potential for applications in the blue-ultraviolet energy range 1,[10][11][12][13][14][15][17][18][19][20] . The main asset of Al over other noble metals stems mainly from a * Corresponding author: aurelien.cuche@cemes.fr plasma frequency ω p situated at a higher energy. In addition to its intrinsic electronic properties, the optical response of aluminum is ...

An optical antenna can convert a propagative optical radiation into a localized excitation and the reciprocal. Although optical antennas can be readily created using resonant nanoparticles (metallic or dielectric) as elementary building blocks, the realization of antennas sustaining multiple resonances over a broad range of frequencies remains a challenging task. Here, we use aluminum self-similar, fractal-like structures as broadband optical antennas. Using electron energy loss spectroscopy, we experimentally evidence that a single aluminum Cayley tree, a simple self-similar structure, sustains multiple plasmonic resonances. The spectral position of these resonances is scalable over a broad spectral range spanning two decades, from ultraviolet to midinfrared. Such multiresonant structures are highly desirable for applications ranging from nonlinear optics to light harvesting and photodetection, as well as surface-enhanced infrared absorption spectroscopy.

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The irradiation of a BOROFLOAT® 33 glass plate with lithographically-fabricated array of aluminum nanodisks on the surface by a focused low-power 523 nm laser beam resulted in the formation of silicon nanocrystals in the subsurface layer of the glass. The nano-Si was registered with Raman scattering technique. The formation of the nano-Si is local and grown nanocrystals are stable.