Our most recent publication appeared one week ago, in the “ASAP” section of Journal of Physical Chemistry Letters. In this work, we have developed a ROKE (resonant optical Kerr effect) spectroscopy setup to monitor the reorientational relaxation time of a solute molecule into a solvent, with a high accuracy and sensitivity. The key experimental factors were to tune the pump and the probe laser beams to the resonant wavelength of the solute, in order to amplify the signal, as well as the heterodyne detection, allowing to determine the relaxation time accurately. The accepted version can be downloaded from our publications page.

In a new publication in ACS Photonics, we show that optical spin orientations can be locked to intracavity propagation directions when a seed of planar (2D) chirality is present inside the cavity. This seed is given by inserting between the two metallic mirrors of a Fabry–Perot cavity a layer of polystyrene made 2D chiral under torsional shear stress. This planar chirality gives rise to an extrinsic source of three-dimensional chirality under oblique illumination that endows the cavities with enantiomorphic signatures measured experimentally and simulated with excellent agreement. The simplicity of this scheme is particularly promising in the context of chiral cavity QED and polaritonic asymmetric chemistry, driven by chiral polaritonic states.

Another paper, resulting from the collaboration between our group and Institute of Electro-Optical Engineering from National Taiwan Normal University, has been published in Nano Letters. Strong coupling provides a powerful way to modify the nonlinear optical properties of materials but the coupling strength is restricted by a weak-field confinement in cavities, which limits the enhancement of the optical nonlinearity. Here, we investigate a strong coupling between Mie resonant modes of high-index dielectric nanocavities and an epsilon-near-zero mode of an ultrathin indium tin oxide film and obtain an anticrossing splitting of 220 meV. In addition, static nonlinear optical measurements reveal a large enhancement in the intensity-independent effective optical nonlinear coefficients, reaching more than 3 orders of magnitude at the coupled resonance.

Just before he went back to India, the paper written by Sandeep Kulangara as first author has been accepted in Journal of Physical Chemistry Letters. The effects of cooperative vibrational strong coupling on the aggregation of two structural isomers of phenyleneethynylene was investigated and showed to lead to two different self-assembled structures, spheres and flakes, having distinct optical properties. These results confirm that VSC can be used to drive molecular assemblies and thereby provide a new tool for supramolecular chemistry.

In addition, Cyriaque Genet just published a perspective on chiral light and chiral matter interactions in ACS Photonics. In this paper, he shows how chiral optical forces shed new light on chiral light−chiral matter interactions. The key advances selected are representative of the vitality of the current research activity and clearly point toward future designs for all-optical chiral separation strategies of high potential.

The left-handed versus right-handed asymmetry of our living world—a “chirality” seen most often in mirror-image architectures of many biomolecules—is one of its most striking features yet one of the most difficult to comprehend. Immersing chiral molecules within chiral environments is an important route to asymmetry, exploited in chemistry for synthesizing and separating chiral molecules according to their handedness. However, the thermodynamics of such a route is not well understood. In a new publication in Physical Review X, we theoretically explore this thermodynamics using a chiral nanoparticle diffusing within a chiral optical light field.

Demonstrating how chiral degrees of freedom can turn into genuine thermodynamics parameters yields a new and rich playground for further exploring chiral light-matter interactions with far-reaching consequences. To that end, we build a stochastic optomechanical model to reveal and control the mechanisms of asymmetry. One central result of our work is to highlight the thermodynamical significance of the coupling between the chirality of the particle and the chirality of the light field.

Our results pave the way to new opportunities in the context of chiral sensing, recognition, and separation of chiral objects at the nanoscale that should now be implemented experimentally and exploited.

Our perspective about chemistry under vibrational strong coupling just appeared in the Journal of the American Chemical Society. We expose the fundamentals of light-matter strong coupling, the recent advancements in vibro-polaritonic chemistry and the numerous perspectives offered by this new approach, that is easy to implement and thus promising for future exploration of light-matter interactions in molecular and material sciences.

A new publication, presenting results obtained in collaboration with National Taiwan Normal University and Shanghai Jiao Tong University just appeared in ACS Photonics. We achieved ultrafast polarization of light by combining the anisotropic optical nonlinear response of ITO at its epsilon-near-zero region with a plasmonic nanoantennas array, at their polarization-sensitive resonance. A rotation of light polarization of more than 30° is obtained together with a π/7 phase change within 600fs. Such a large anisotropic nonlinearity is a significant step towards the realization of ultrafast polarization modulators and phase retarders.

A new publication just appeared in Angewandte Chemie International Edition , in collaboration with IPCMS, Strasbourg, and University of Heidelberg. We studied the self-assembly of a conjugated polymer under vibrational strong coupling. It appeared under electron microcopy that the supramolecular morphology is totally different from that observed in the absence of strong coupling. Morever the self-assembly kinetics is modified and depends on which bond of the solvent is coupled.

A review entitled “Manipulating matter by strong-coupling to vacuum field” just appeared in Science. It has been written by Pr T.W. Ebbesen in collaboration with Pr. F. Garcia-Vidal and Pr. C. Ciuti and it summarizes the actual knowledge on the surprizing implications of the strong coupling regime on matter properties, both on an experimental and theoretical point of view.

(Left) Charge transfer complexation between mesitylene and iodide(courtesy of K. Nagarajan). (Right) Energy transfer between donor and acceptor molecules (courtesy of J. Galego)

We are pleased to announce two new publications.

First, our paper about the enhancement of the ferromagnetism of YBCO nanoparticles under strong-coupling has been accepted in Nano Letters and is now available in open access. Making use of cooperative strong-coupling, we measured a strong ferromagnetism even at room temperature, that competes with superconductivity below the Tc of YBCO. Thanks and congratulations to our collaborators from IPCMS !

Second we published a “Feature Article” in Physics Today, in collaboration with Jérôme Faist from ETH Zürich, dealing with the control of new properties in materials via the hybrid light-matter states created in optical cavities.

To read by the fireside during this rainy and cool spring !