Past Event

Frank Koppens - ICFO

February 19, 2020
3:30 PM - 4:30 PM
705 Pupin Hall

"Stacking and twisting 2D materials for quantum nano-optoelectronics"

Two-dimensional (2D) materials offer extraordinary potential for control of light and lightmatter interactions at the atomic scale. In this talk, we will show a new toolbox to exploit the collective motion of light and charges as a probe for topological, hyperbolic and quantum phenomona. We twist or nanostructure heterostructures of 2D materials that carry optical excitations such as excitons, plasmons or hyperbolic phonon polaritons. Nanoscale optical techniques such as near-field optical microscopy reveal with nanometer spatial resolution unique observations of topological domain wall boundaries, hyperbolic phononic cavities [1], and interband collective modes in charge neutral twisted-bilayer graphene near the magic angle [2]. The freedom to engineer these so-called optical and electronic quantum metamaterials [3] is expected to expose a myriad of unexpected phenomena.

We will also show a new type of graphene-based magnetic-resonance that we use to realize single, nanometric-scale cavities of ultra-confined acoustic graphene plasmons [4]. We reach record-breaking mode volume confinement factors of ∼ 5 · 10-10. This AGP cavity acts as a Midinfrared nanoantenna, which is efficiently excited from the far-field, and electrically tuneable over an ultra-broadband spectrum. Finally, we present near-unity light absorption in a monolayer WS2 van der Waals heterostructure cavity [5].

[1] Herzig Sheinfux et al., in preparation
[2] Hesp et al., Arxiv 1910.07893
[3] Song, Gabor et. al., Nature Nanotechnology (2019)
[4] Epstein et al., Arxiv 2002.00366
[5] Epstein et al., Arxiv 1908.07598