Alexandre Baron
CRPP, Université de Bordeaux

“Self-assembled meta-atoms and metasurfaces : Huygens multipoles and homogenization problems”

Meta-atoms are structured artificial nanomaterials designed and assembled to have specific polarizabilities that determine their light absorption and scattering properties. Usually, this procedure is used to achieve strong and resonant behavior that does not exist in natural atoms or molecules. A subclass of resonant meta-atoms are the so-called Huygens scatterers that act as sources of hemispherical wavelets that emit in a direction imposed by the polarization of the electric and magnetic dipoles [1], just like the fictitious point-sources invoked in the Huygens-Fresnel principle. In recent years, it was shown that such sources could be obtained in general by any scatterer containing multipoles of even and odd parity that have equal phases and amplitudes. Such scatterers are referred to as “generalized Huygens scatterers” [2].

In recent years, bottom-up fabrication and self-assembly techniques have emerged as prominent providers of massive amounts of meta-atoms that come in the form of colloidal suspensions or inks that can be assembled into two- or three-dimensional materials [3,4].

We shall review recent realizations of generalized Huygens scatterers by the self-assembly route. They come in various geometries [5-7]. We shall describe the fundamental theory and design of such sources, the fabrication techniques of meta-atoms as well as the optical characterization of these structures and possible applications of Huygens scatterers. Finally, an attempt to homogenize dense plasmonic clusters that act as efficient Huygens sources shall be presented.

[1] R. Dezert, P. Richetti, and A. Baron, Phys. Rev. B, 96, 180201, (2017)
[2] R. Dezert, P. Richetti, and A. Baron, Opt. Express, 27, 26317-26330, (2019)
[3] A. Aradian, P. Barois, O. Mondain-Monval, V. Ponsinet, and A. Baron, Chap. 3. in Hybrid Flatland Metastructures, ed. by R. Caputo and G. E. Lio, AIP Publishing, Melville, New York, (Nov. 2021)
[4] L. Lermusiaux, L. Roach, A. Baron, & M. Tréguer-Delapierre. Nano Express 3, 021003, (2022)
[5] R. Elancheliyan, R. Dezert, S. Castano, A. Bentaleb, E. Nativ-Roth, O. Regev, P. Barois, A. Baron, O. Mondain-Monval, and V. Ponsinet, Nanoscale 12, 24177-24187, 12, 24177-24187, (2020)
[6] M. L. De Marco, T. Jiang, J. Fang, S. Lacomme, Y. Zheng, A. Baron, B. A. Korgel, P. Barois, G. L. Drisko, and C. Aymonier, Adv. Funct. Mater. 31, 2100915, (2021)
[7]L. Lermusiaux, V. Many, P. Barois, V. Ponsinet, S. Ravaine, E. Duguet, M. Tréguer-Delapierre, and A. Baron, Nano Lett. 21, 2046-2052, (2021)