Nanophotonics and quantum optics – Ellipsometry

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Manipulation of light by plasmonic nanostructures

We can modify the propagation of electromagnetic waves in materials by structuring them in two or three dimensions at scales far below the wavelength. The resulting materials are generically called ‘metamaterials’. From this point of view, plasmon resonators are particularly interesting since they interact strongly with light. The main objective of our work is to explore the potential of metallic nanostructures to enhance far-field chiral optical responses with the idea of moving towards the creation of near-field chiral light.

Our work is mainly experimental (realization of materials, measurements ofoptical properties), but uses numerical or theoretical modeling in order to interpret the measurements and understand the mechanisms at the origin of the observed effects. We realize metasurfaces (2D arrangements of resonators) by electronic lithography. Polarimetric measurements are performed on a spectroscopic ellipsometer (193 nm – 2500 nm) which provides access to complete polarimetric information (measurement of the polarization state of light after interaction with the metasurface).

Figure(a) SEM image of a gold resonator array made by electron lithography. (b) Spectroscopic variations of the circular dichroism as a function of the propagation direction measured at fixed incidence. An inversion of the sign of the dichroism is observed for two directions of propagation symmetrical with respect to the surface normal (90° and 270° directions).



  • Bruno Gallas : bruno.gallas(at)insp.jussieu.f