"Dielectric optically-active metamaterials: are they achievable through bottom-up chemistry?"

Vous êtes cordialement invité au séminaire de Glenna L. DRISKO, CNRS researcher ICMCB - UMR5026 Bordeaux, organisé par l'IPCMS

Resumé :The advent of metamaterials consisted of a flurry of activity around plasmonic resonators. Fifteen years of research has confirmed that plasmonic-based materials absorb too much light to be used in optically-active metamaterials. High refractive index materials theoretically provide an alternative to plasmonics. Semiconductors boast the highest refractive index across the visible spectrum among naturally occurring materials. Silicon is generally favored for optical applications due to its natural abundance, omnipresence in the electronics industry, and relatively easy synthesis compared to other semiconductors. However, even silicon is extremely difficult to fabricate using bottom-up chemistry. It is relatively easy to produce 10 nm silicon particles, however these are too small for optically-active meta-atoms and such small particles oxidize completely to low-refractive index SiO2. This begs asking, what silicon forms can we realistically expect to produce? And are there alternatives to silicon?

Metamaterials produced via bottom-up synthesis methods require the preparation of individual resonant particles, referred to as meta-atoms, and then the assembly of these particles into a 2D or 3D material. My group has approached the synthesis of silicon meta-atoms by examining the effect of the nature of the solvent, silicon precursor, reducing agent and processing conditions on the silicon particle diameter, polydispersity and crystallinity. Through these lessons, we have come closer to ideal silicon meta-atoms. We have also begun research into less optically fantastic, but more easily obtained TiO2 nanoparticles. I will present the synthesis methods, optical measurements and future prospects of these dielectric meta-atoms. I will also present the plasmonic-based metamaterials produced previously in the team, to showcase what can be achieved using bottom-up chemistry.

Contact: Bertrand Donnio, bdonnio@ipcms.unistra.fr