Description du sujet de thèse

Chiral cavities have been the subject of intense investigation in optics and metamaterials due to their potential to generate strong chiral electromagnetic fields that can selectively interact with other objects within these cavities. This coupling can induce a change in the physical and chemical properties of the material embedded in the cavity, leading to novel properties such as circularly polarized luminescence or enantioselective chemistry. Currently, most research on chiral cavities is theoretical. Experimental implementation of such cavities is challenging because typical reflective surfaces reverse the handedness (helicity) of light upon reflection, cancelling out any chiral differentiation within the cavity. To overcome this, chiral mirrors, which preserve the helicity of light upon reflection, are required. The first demonstration of chiral reflectivity in 2015 was limited to the microwave region and was later extended to the infrared and visible ranges using lithography. We have recently demonstrated that chiral mirrors can be prepared by a bottom-up approach based on the oriented assembly of plasmonic nanowires on surfaces.6

In this collaborative project between the Chemistry Laboratory of the Ecole Normale Supérieure in Lyon and the Institute of Supramolecular Science and Engineering of the University of Strasbourg, we propose to build chiral cavities from self-assembled chiral mirrors, to characterize their structure-dependent optical properties, and to study the chiral light-matter coupling in these cavities. This work is part of a wider interdisciplinary project funded by the PEPR LUMA, involving 17 teams in France working in chemistry, materials science, nanophotonics, optics, and spectroscopy, with the aim of understanding and controlling chiral light-matter interactions with potential spin-offs in optoelectronics, asymmetric synthesis, and quantum information processing.
Grazing Incidence Spraying (GIS) will be used to assemble silver nanowires into oriented mono− and multilayer thin films with well-controlled orientation and spacing. GIS will be combined with the Layer-by-Layer (LbL) approach to build chiral multilayer superstructures that exhibit a very high circular dichroism over a wide wavelength range, both in transmission and in reflection. These chiral mirrors will be used to build a chiral cavity, whose structure will be systematically characterized using various microscopy techniques (AFM, SEM, TEM), and whose optical properties will be measured by combining different spectroscopic and polarimetric approaches (including UV-Vis-NIR polarized spectroscopy, ellipsometry, Mueller Matrix Polarimetry and CD spectroscopy). The cavities will be coupled with different materials to study how the optoelectronic and chemical properties of the embedded material are modified by (strong) chiral light-matter coupling.

Contexte de travail

The PhD student (M/F) will be assigned to the “Molecules and Nano-Materials for Optics” axis of the Chemistry Laboratory (LCH) at ENS Lyon. The LCH develops interdisciplinary research projects at the crossroads of biology, materials science and physics, from fundamental to more applied science. It brings together researchers with a wide range of expertise in synthesis (organic, inorganic, (nano)materials, materials processing), characterization and advanced spectroscopies, in conjunction with a strong expertise in atomistic modeling (excited states, reactivity, liquids). In particular the “Molecules and Nano-Materials for Optics” axis brings together multidisciplinary expertise in molecular chemistry, materials science and photonics to develop innovative systems based on (nano)functional materials, with applications in healthcare, energy, communications and the environment.

This work will be carried out in close collaboration with the Light-Matter Interactions Laboratory of the Institut de Science et d'Ingénierie Supramoléculaires (ISIS) at the University of Strasbourg. ISIS develops exploratory research in a wide range of scientific fields, around the general theme of complex matter. Topics covered at ISIS include nanoscience and materials science, the study of self-organization processes and adaptive chemistry, nanophotonics, plasmonics and strong light-molecule coupling, and supramolecular self-assembly. In particular, light-matter interactions are at the core of research in the Laboratory of light-matter interactions in complex systems at ISIS, ranging from optical forces, chirality and plasmonics to weak and strong coupling regimes.

This multidisciplinary thesis work is at the interface of nanoscience, materials science, chemistry and optics. The thesis is intended for a candidate with a strong background in physical chemistry, materials science, nanoscience or physics.
The application should include a letter of motivation, a curriculum vitae, and a list of courses and grades taken at the master's level.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

The PhD student (M/F) will be made aware of and trained on the risks inherent to his/her work environment.