Jayeeta Amboli will defend her PhD thesis entitled "Design and analysis of optical metasurfaces for tailoring near and far-field chirality", on Monday, December 18, at 01.30 p.m. in the Amphi Ponte. The slides and the presentation will be in English. You could also Join on Zoom Meeting.
The thesis jury committee will include :
Stéphane LANTERI, Director of research, Inria, Université Côte d’Azur, France - Reviewer
Davy GÉRARD, Assistant Professor, UTT, France - Reviewer
Lydie FERRIER, Assistant Professor, INSA Lyon, France - Examiner
Céline FIORINI-DEBUISSCHERT, Director of research, Université Paris-Saclay, France - Examiner
Brian STOUT, Professor, Institut Fresnel, France - Examiner
Bruno GALLAS, Researcher, Sorbonne Université, France - Invited member
Nicolas BONOD, Director of research, Institut Fresnel, France - Thesis director
Guillaume DEMÉSY, Assistant Professor, Institut Fresnel, France - Thesis co-director
Abstract : Chirality is a fundamental geometric property with critical implications in chemistry, biology, and materials science. Enantiomers, mirror-image forms of chiral molecules, can exert vastly different effects on biological systems, making this concept particularly significant in the pharmaceutical industry where drug enantiomers can have distinct, even harmful, impacts. Chiral sensing involves various optical techniques, with circular dichroism (CD) spectroscopy standing out. CD discriminates enantiomers by measuring the differential absorption of left and right circularly polarized light, relying on their enantioselective interaction with chiral molecules. The weak UVregion molecular CD signal has driven researchers toward optimizing the interaction between light and chiral matter. Plasmonic and dielectric metasurfaces have emerged as promising avenues, substantially amplifying CD signals through pronounced nearfield optical chirality. These engineered structuresmanipulate light properties, revolutionizing chiral sensing by enhancing polarization and phase control. This thesis systematically investigates the polarimetric properties of various metasurfaces and their potential for chiralmolecule detection. It advances in two key directions : understanding the polarimetric behavior of achiral, chiral, and pseudo-chiral metasurfaces through a comprehensive Stokes-Mueller matrix study, with a focus on their circular dichroism response, and harnessing them for advanced background-free chiral sensing platforms. The innovative metasurface designs include (i) a chiral structure composed of fourMie-resonant Si-based nano-disks per cell with heights varying on left or right circular directions, (ii) a plasmonic metasurface composed of inverted gold U-shaped resonators, and (iii) an achiralmetasurface composed of TiO2-based nano-disks. The first metasurface displayed strong optical activity, while the second demonstrated successful background-free sensing. The thirdmetasurface exhibited significant chiral enhancement surpassing the capabilities of the current state-ofthe-art solutions. This thesis bridges versatile numerical techniques, the underlying physics of optical metasurfaces, and their potential applications in biosensing.
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