SEL 2022

From 09/12/2022 to 09/23/2022

La Vieille Perrotine - CAES du CNRS - 140 Route des Allards, 17310 Saint Pierre d'Oléron

Confirmed Invited speaker

Lucien Saviot, LICB, France
Peter Torök, SCELSE, Singapore
Hervé Rigneault, FRESNEL institute, France
Alberto Bilenca, Ben-Gurion University, Israel
Francesca Palombo, University of Exceter, UK
Robert Prevedel, EMBL, Germany
Pascal Ruello, IMMM, France
Aurélien Crut, iLM, France
Arnaud Arbouet, CEMES, France
Elsa Cassette, LuMIN UMR 9024 Universite Paris-Saclay, ENS Paris-Saclay, CNRS, CentraleSupélec, France
Eva Weig, Universität Konstanz, Germany
Valentina Giordano, ILM, France
Birgit Stiller, Max Planck Institute, Germany
Luc Thévenaz, EPFL, Switzerland
Thomas Dehoux, iLM, France
Philip Russel, Max Planck Institute, Germany
Kerry Vahala, CALTECH, USA
Daniel Kimura, C2N, France
Nathalie Lidgi-Guigui, LSPM, France
Lukas Jakob, University of Cambridge, England
Bernard Perrin, INSP, France
Gregory Hartland, University of Notre Dame, USA
Silvia Boccato, IMPMC, France
Kareem Elsayad - Medical University of Vienna, Austria
Ivan Favero, MPQ, univ Paris Diderot

Lucien Saviot
Laboratoire Interdisciplinaire Carnot de Bourgogne
UMR 6303 CNRS-Université Bourgogne Franche-Comté
9 Avenue Alain Savary, BP 47 870, 21078 Dijon Cedex

Dr. Lucien Saviot is a CNRS senior researcher at Université de Bourgogne in Dijon. His main research activity is devoted to the vibrational spectroscopy of nanomaterials. He is interested in particular in inelastic light scattering by acoustic vibrations of nano-objects having various composition (semiconductor, metal, metal oxide), shape (sphere, rod, platelet, cube) and crystallinity (isotropic, cubic, ...).

Acoustic vibrations of nano-objects
Keywords: nanoparticles, Raman scattering, acoustic vibrations, crystallinity, symmetry
Summary: Acoustic vibrations of nanoparticles were first observed using inelastic light scattering 4 decades ago. Significant advances in the synthesis of nano-objects and frequency and time-domain spectroscopy techniques have made it possible to investigate the sensitivity of these vibrations to the structure (size, shape, crystal structure) and environment of the nano-objects. This lecture will present an overview of this field and focus in particular on recent experimental results and models required to describe the acoustic vibrations of various kinds of nano-objects and their symmetry.
- E. Duval, A. Boukenter, and B. Champagnon, Phys. Rev. Lett. 56, 2052 (1986)
- H. Portalès, N. Goubet, S. Casale, X. Z. Xu, M. Ariane, A. Mermet, J. Margueritat, and L. Saviot, ACS Nano 14, 4395 (2020)

Kerry Vahala
California Institute of Technology

Vahala studies devices called optical microcavities and their application to miniature frequency and time systems, microwave sources, parametric oscillators, astrocombs and gyroscopes. A member of the National Academy of Engineering and fellow of the IEEE and OSA, he received the IEEE Sarnoff Medal for research on quantum-well laser dynamics, the Alexander von Humboldt Award for work on ultra-high-Q optical microcavities, a NASA achievement award for application of microcombs to exoplanet detection, and the OSA Forman Team Engineering Excellence Award for a 2-photon optical clock.

Brillouin Physics in High-Q Microresonators and Applications
Keywords: Brillouin, Microresonator, Nonlinear optics, Microcavity
Summary: Over the last decade an approach for generation of Brillouin lasers has emerged with implications for miniaturization and integration with other photonic devices as well as electronics. These devices generate Brillouin gain in compact high-Q optical cavities that are most often of the whispering-gallery-mode type wherein optical waves execute closed circular paths [1]. When the round trip optical loss in these resonators is very low (equivalently, the optical Q is very high), resonant enhancement of input couped power is large, making possible access to the stimulated Brillouin process at remarkably low pumping power levels less than 1 mW [2,3,4]. Such power levels are readily attainable with III-V semiconductor lasers. Also significant is that the high optical Q reduces the fundamental laser laser linewidth to below 1 Hz. The physics and microfabrication of these devices will be reviewed, followed by discussion of their application to Sagnac gyroscopes [5,6] as well as high-performance microwave signal sources [7,8].
[1] K. Vahala, Nature, (2003).
[2] Lee, H. et al. Chemically etched ultrahigh-Q wedge-resonator on a silicon chip. Nat. Photon. 6, 369–373 (2012).
[3] Tomes, M. & Carmon, T. Photonic micro-electromechanical systems vibrating at X-band (11-GHz) rates. Phys. Rev. Lett. 102, 113601 (2009).
[4] Grudinin, I. S., Matsko, A. B. & Maleki, L. Brillouin lasing with a CaF2 whispering gallery mode resonator. Phys. Rev. Lett. 102, 043902 (2009).
[5] Li, J., Suh, M.-G. & Vahala, K. Microresonator Brillouin gyroscope. Optica 4, 346–348 (2017).
[6] Yu-Hung Lai, Myoung-Gyun Suh, Yu-Kun Lu, Boqiang Shen, Qi-Fan Yang, Heming Wang, Jiang Li, Seung Hoon Lee, Ki Youl Yang, Kerry Vahala, "Earth rotation measured by a chip-scale ring laser gyroscope", Nature Photonics 14, 345-349 (2020)
[7] Li, J., Lee, H. & Vahala, K. J. Microwave synthesizer using an on-chip Brillouin oscillator. Nat. Commun. 4, 2097 (2013).
[8] Li, J., Yi, X., Lee, H., Diddams, S. A. & Vahala, K. J. Electro-optical frequency division and stable microwave synthesis. Science 345, 309–313 (2014).

Hervé Rigneault
Institut Fresnel, Aix Marseille Univ - CNRS - Ecole Centrale Marseille

Hervé Rigneault is a CNRS research director in the Mosaic group that he leads at the Fresnel Institute (Marseille France) ( . He is the author and co-author of 260 publications in the field of optics and biophotonics. His current field of research encompass molecular spectroscopy and imaging using coherent microscopy and endoscopy.

Coherent Raman imaging: from principle to applications
Keywords: Raman, coherent Raman, stimulated Raman, Microscopy, endoscopy
Summary: The first part of the lecture will present the basics of coherent Raman light matter interaction for molecular spectroscopy and imaging. The second part will be devoted to coherent Raman technology in microscopy and endoscopy whereas the last part of the lecture will address the applications in the fields of chemical imaging, biological and medical sciences.
H. Rigneault, and P. Berto, "Tutorial: Coherent Raman light matter interaction processes," APL Photonics 3, 091101 (2018).
X. Audier, S. Heuke, P. Volz, I. Rimke, and H. Rigneault, "Noise in stimulated Raman scattering measurement: From basics to practice," APL Photonics 5, 011101 (2020).
R. A. Bartels, D. Oron, and H. Rigneault, "Low frequency coherent Raman spectroscopy," Journal of Physics: Photonics 3, 042004 (2021).
J. X. Cheng, W. Min, Y. Ozeki, and D. Polli, Stimulated Raman Scattering Microscopy: Techniques and Applications (Elsevier Science, 2021).

Alberto Bilenca
Ben-Gurion University of the Negev, Israel

Alberto Bilenca is an Associate Professor in the Ben-Gurion University of the Negev, Israel. His research interests are in optical imaging and diagnosis, with focus on stimulated Brillouin microscopy.

Stimulated Brillouin scattering microscopy for mechanical imaging of cells and organisms
Keywords: Stimulated Brillouin scattering, biomicroscopy, bioimaging, biomechanics
Summary: The mechanical properties of biological systems, such as cells and organisms, play a major role in their function and development. A well-established technique for assessing biomechanics is atomic-force microscopy; yet, it requires physical contact with the sample. Recently, Brillouin microscopy has been developed for biomechanical imaging with no sample contact or need for external mechanical stimuli. Whereas most of the developmental efforts in Brillouin microscopy have been using spontaneous Brillouin scattering as the contrast mechanism, I will introduce here a new approach for high sensitivity and specificity, noncontact, biomechanical-contrast imaging based on stimulated Brillouin scattering (SBS). The physical working principles of the method and its use in biological settings will be described and discussed.
Itay Remer, Roni Shaashoua, Netta Shemesh, Anat Ben-Zvi, Alberto Bilenca, “High-sensitivity and high-specificity biomechanical imaging by stimulated Brillouin scattering microscopy,” Nat Methods 17, 913-916 (2020).
Itay Remer, Lear Cohen, Alberto Bilenca, “High-speed continuous-wave stimulated Brillouin scattering spectrometer for material analysis,” J Vis Exp 127, 55527 (2017).

Lidgi-Guigui Nathalie
LSPM (Laboratoire de Sciences des Procédés et des Matériaux) Université Sorbonne Paris Nord

I am associate professor at the University Sorbonne Paris Nord. I am a specialist of the growth, optical and electronic properties of metallic nanoparticles. I have developed my research in the field of molecular plasmonics where I have used metallic nanoparticles for the detection of biomarkers and contaminants in complex media. For this I have studied different ways of surface functionalization including some activated by the plasmons.

Sensing with plasmons and Raman scattering
Keywords: Plasmons, Raman scattering, Surface Enhanced Raman Scattering, biosensing, sensing
Summary: During this course I will start by briefly presenting the physics of surface and localised plasmons. I will then present how these localized surface plasmons can be used to enhance Raman scattering.
In a second part I will discuss the notion of molecular detection based on plasmons and Raman spectroscopy. I will consider in particular the detection of biomolecules in complex media such as blood or urine. For this I will introduce very basics notions of molecular biology and surface chemistry.

Birgit Stiller
Max-Planck-Institute for the Science of Light, Erlangen, Germany

Birgit Stiller is an experimental physicist and the leader of an independent Max Planck Research Group at the Max Planck Institute for the Science of Light (MPL) in Erlangen, Germany. Her group’s interest is on Brillouin scattering and optoacoustic interactions in waveguides and optical fibers at the classical and quantum level. Her wider research background is in nonlinear optics, quantum communications and integrated optics. Before she held a position as Postdoctoral Research Fellow at the University of Sydney, Australia, and was a Postdoctoral Researcher in the field of quantum cryptography in Erlangen. She received her PhD from the CNRS Institute FEMTO-ST Besançon, France.

Storing light into sound waves and Brillouin-based signal processing
Keywords: Stimulated Brillouin scattering, optoacoustic light storage, nonlinear optical signal processing, photonic circuits, photonic crystal fibers
Summary: Optical and traveling acoustic waves can interact over the coherent process of stimulated Brillouin scattering (SBS), which is a third-order nonlinear optical effect. SBS has been of crucial importance for applications in optical fiber sensing, microwave photonics, Brillouin lasers and signal processing. The latter includes calculus operations and signal amplification but also light storage of signal streams [1,2]. By using traveling acoustic waves, we recently showed proof-of-principle experiments of Brillouin-based light storage [2–7], such as the tunable delay and coherent retrieval of an optical signal [2], as well as cascaded storage at different spatial positions [3].
A particularity of Brillouin-based light storage is the strict phase-matching condition. This allows for different features: nonreciprocal storage over a large bandwidth [4] and simultaneous storage at multiple wavelengths with negligible crosstalk [5], which distinguishes the waveguide approach from optomechanical resonators. The delay time of this technique has so far been limited to the acoustic lifetime of about 10 ns. In recent results though, we were able to experimentally demonstrate how to reinforce acoustic phonons to overcome the obstacle of the limited acoustic lifetime. We showed for the first time the storage of amplitude and phase of an optical signal via stimulated Brillouin scattering up to 40 ns, which can potentially be further expanded [6]. Another interesting topic is the optoacoustic interaction of short pulses whose bandwidth is well beyond the Brillouin linewidth [7]. We have experimentally demonstrated the SBS interaction of optical pulses down to 150 ps and achieved a time-delay in Brillouin-based memory of 100 pulse-widths [8].
In this talk, I will give an overview about light storage and optoacoustic signal processing [9], speak about the challenges and chances of waveguide optoacoustics via SBS [10-12] and present recent achievements in more exotic types of waveguides: liquid-filled capillary fibers and twisted photonic crystal fibers [12].
[1] Zhu et al, Science 318, 1748 (2007)
[2] Merklein et al., Nature Comm. 8 (2017)
[3] Stiller et al., Optics Letters 43 (18) (2018)
[4] Merklein et al., Nanophotonics 10(1) (2020)
[5] Stiller et al., APL Photonics 4 (2019)
[6] Stiller et al., Optica, 5 (7) (2020)
[7] Piotrowski et al., Optics Letters 46, 2972 (2021)
[8] Jaksch et al., in Frontiers in Optics 2017, PDP paper FTh4A.5
[9] Merklein et al., Review, Journal of Optics (2018)
[10] Wolff et al., Invited Tutorial, Josa B 38 (4) (2021)
[11] Zarifi et al., Josa B 36(1) (2019)
[12] Zarifi et al., APL Photonics 3 (2018)
[13] Zeng et al., Photonics Research (2022)

Robert Prevedel
European Molecular Biology Laboratory (EMBL), Heidelberg, Germany

Robert Prevedel is a group leader at the European Molecular Biology Laboratory, Heidelberg (Germany). His primary research interest lies in developing advanced and innovative optical techniques for biomedical imaging, such as multi-photon and light field-microscopy, photo-acoustics or Brillouin spectroscopy. Robert holds a PhD in experimental physics from the University of Vienna (Austria) and performed postdoctoral research at the University of Waterloo (Canada) and at the Institute of Molecular Pathology in Vienna (Austria).

Brillouin microscopy: an emerging tool for mechanobiology
Keywords: Brillouin microscopy, biomechanics, bio-imaging
Summary: Mechanical properties of cells and tissues have been shown to play a crucial role in development and disease, but standard techniques for probing them are usually invasive and limited to the sample’s surface. In contrast, Brillouin microscopy [1–3] is an emerging optical technique that enables non-contact measurement of viscoelastic properties of a material with diffraction-limited resolution in 3D. In my lecture, I will briefly introduce and review this emerging field before discussing our current efforts to study the role of mechanical properties in developing organisms such as zebrafish and drosophila embryos, as well as in the early detection of disease.
1. G. Scarcelli and S. H. Yun, "Confocal Brillouin microscopy for three-dimensional mechanical imaging," Nat Phot. 2, 39–43 (2008).
2. R. Prevedel, A. Diz-Muñoz, G. Ruocco, and G. Antonacci, "Brillouin microscopy: an emerging tool for mechanobiology," Nat. Methods 16, 969–977 (2019).
3. G. Antonacci, T. Beck, A. Bilenca, J. Czarske, K. Elsayad, J. Guck, K. Kim, B. Krug, F. Palombo, R. Prevedel, and G. Scarcelli, "Recent progress and current opinions in Brillouin microscopy for life science applications," Biophys. Rev. 12, 615–624 (2020).

Aurélien Crut
Institut Lumière Matière (Lyon)

Aurélien Crut studied physics at Ecole Polytechnique (France). His PhD and postdoctoral studies (respectively at the Kastler-Brossel laboratory in Paris and at Delft Technical University in the Netherlands) were devoted to biophysical experiments at the single-molecule level. In 2007, he was appointed Assistant Professor and joined the FemtoNanoOptics group at the Institut Lumière Matière of University Lyon 1, specialized in optical investigations of nanomaterials. His present research is focused on the modeling of the optical, vibrational and thermal properties of nano-objects.

Vibrational and Cooling Dynamics of Metal Nanoparticles: Optical Investigations and Modeling
Keywords: metal nanoparticles, time-resolved spectroscopy, vibration modes, single-particle spectroscopy, interfacial phonon transfer, plasmonics
Summary: Nano-objects exhibit discrete vibrational modes and fast cooling dynamics, which can both be monitored in the time domain using ultrafast optical pump-probe spectroscopy. This approach enables fundamental investigations of the laws governing elasticity and heat transfer at the nanoscale. Experimental investigations have in particular demonstrated the surprising ability of continuum elasticity models to reproduce the vibrational frequencies of metal nanoparticles and highlighted the crucial role played by interface thermal resistances on their cooling kinetics. Performing time-resolved experiments on single nanoparticles rather than on ensembles allows even more detailed comparisons between the measured and modeled vibrational and cooling dynamics, and is currently leading to a better understanding of vibrational damping and of the transient optical response induced by nanoscale energy transfer phenomena.
1) A. Crut, P. Maioli, N. Del Fatti and F. Vallée Optical absorption and scattering spectroscopies of single nano-objects Chem. Soc. Rev. 43, 3921 (2014).
2) A. Crut, P. Maioli, N. Del Fatti and F. Vallée Acoustic vibrations of metal nano-objects: time-domain investigations Phys. Rep. 549, 1 (2015).
3) F. Medeghini, A. Crut, M. Gandolfi, F. Rossella, P. Maioli, F. Vallée, F. Banfi and N. Del Fatti Controlling the Quality Factor of a Single Acoustic Nanoresonator by Tuning its Morphology Nano Lett. 18 5159 (2018).
4) R. Rouxel, M. Diego, F. Medeghini, P. Maioli, F. Rossella, F. Vallée, F. Banfi, A. Crut, and N. Del Fatti Ultrafast Thermo-Optical Dynamics of a Single Metal Nano-Object J. Phys. Chem. C 124 15625 (2020).

Silvia Boccato
IMPMC – CNRS – Sorbonne University

After completing my Physics Engineering degree, I obtained my Ph.D. in 2017 at the European Synchrotron Radiation Facility, working on the determination of melting curves and liquid structure of transition metals such as nickel and cobalt with x-ray absorption spectroscopy. In my post-doc at the Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, I started working on the determination of sound velocities of iron alloys under pressure by means of picosecond acoustics.

Picosecond Acoustics: a Laser Pump-Probe Technique for the Determination of Thermo-Elastic Properties of Solids and Liquids at High Pressure and High Temperature
Keywords: picosecond acoustics, elastic constants, sound velocity, high pressure, high temperature
Summary: Picosecond acoustics is a time-resolved optical pump-probe technique that allows studying the propagation of acoustic echoes in a large variety of samples at different pressure and temperature conditions. With this technique we can access melting curves, the complete set of elastic moduli for single crystals and longitudinal velocities for polycrystalline samples.
I will illustrate the importance of these experiments for Earth and planetary science, providing examples of studies with a direct interest in these fields, including measurements on iron and iron alloys, metallic liquids, hydrogen and deuterium. Finally, I will present the recent development we performed at IMPMC consisting in the coupling of picosecond acoustic to a laser heating system. This allows to reach pressure and temperature conditions relevant for planetary interiors.
Decremps et al. Ultrasonics 56, 129–140 (2015)
Goncharov et al. Physical Review B 95, 214104 (2017)
Edmund et al. Minerals 10, 214 (2020)

Philip Russell
MPL Erlangen (Emeritus director) & RCALS Hangzhou (Director)

Professor Philip Russell is an emeritus founding Director of the Max-Planck Institute for the Science of Light (MPL) in Erlangen, Germany and since 2022 has been Director of the RCALS Centre for Advanced Lightwave Science in Hangzhou, China. He is a Fellow of the Royal Society and Optica (formerly The Optical Society, OSA) and has received a number of awards recognising his work on photonic crystal fi-bres and their numerous scientific and commercial applications, including in optoacoustics and optome-chanics. He was OSA's president in 2015, the International Year of Light.

Optomechanical Phenomena in Photonic Crystal Fibres
Summary: Photonic crystal fibre (PCF) technology makes it possible to produce long lengths of very small (scale of 1 µm) glass cores surrounded by hollow channels. Such cores support tightly confined few-GHz acoustic resonances and offer close-to-100% optoacoustic overlap, providing a unique system for achieving stable passive high harmonic mode-locking of fibre lasers [1] [2]. Light can be guided in hollow core PCF over long distances in a well-controlled single mode, allowing the trapping and laser propulsion of small parti-cles to be studied. Among recent experiments include optical binding of particles at cm-scale distanc-es [3], continuous monitoring of PM2.5 particles in the atmosphere [4], precession and nutation of bire-fringent particles driven by circularly polarized light in chiral PCF [5], ablation-driven rocket-like propul-sion of particles by single fs pulses [6] and optomechanically stabilized launching of light into hollow core PCF using a mechanically compliant glass nanospike [7] [8].
1. W. He, M. Pang, D.-H. Yeh, J. Huang, C. R. Menyuk, and P. St. J. Russell, "Supramolecular transmission of soliton-encoded bit streams over astronomical distances," Nat. Comm. 10, 5756 (2019).
2. D.-H. Yeh, W. He, M. Pang, X. Jiang, G. K. L. Wong, and P. St. J. Russell, "Pulse-repetition-rate tuning of a harmonically mode-locked fiber laser using a tapered photonic crystal fiber," Opt. Lett. 44, 1580–1583 (2019).
3. A. Sharma, S. Xie, and P. St. J. Russell, "Reconfigurable millimeter-range optical binding of dielectric microparticles in hollow-core photonic crystal fiber," Opt. Lett. 46, 3909 (2021).
4. A. Sharma, S. Xie, R. Zeltner, and P. St. J. Russell, "On-the-fly particle metrology in hollow-core photonic crystal fibre," Opt. Exp. 27, 34496–34504 (2019).
5. S. Xie, A. Sharma, M. Romodina, N. Y. Joly, and P. St. J. Russell, "Tumbling and anomalous alignment of optically levitated anisotropic microparticles in chiral hollow-core photonic crystal fiber," Sci. Adv. 7, eabf6053 (2021).
6. M. N. Romodina, S. Xie, A. Sharma, F. Tani, and P. St. J. Russell, "Femtosecond laser micromachining and rocket propulsion of micro-particles optically trapped in hollow-core photonic crystal fibre," in CLEO/Europe and EQEC 2021 Conference Digest (2021), p. paper CM-5.1 THU.
7. S. Xie, R. Pennetta, and P. St. J. Russell, "Self-alignment of glass fiber nanospike by optomechanical back-action in hollow-core photonic crystal fiber," Optica 3, 277–282 (2016).
8. S. Xie, R. Pennetta, Z. Wang, and P. St. J. Russell, "Sustained self-starting orbital motion of a glass-fiber “nanoengine” driven by photophoretic forces," ACS Photonics 12, 3315–3320 (2019).

Elsa Cassette
Laboratoire Lumière, Matière et Interfaces (LuMIn, UMR 9024, Université Paris-Saclay, ENS Paris-Saclay, CNRS, CentraleSupélec)

E. Cassette received her PhD from the University Paris VI in 2012 for her work at the LPEM laboratory (ESPCI, France) on the synthesis and properties of colloidal II-VI and I-III-VI semiconductor core/shell nanocrystals. She then joined the group of Gregory Scholes as a postdoctoral researcher (Toronto, Canada and Princeton, USA) to study the ultrafast exciton dynamics in 2D II-VI semiconductor nanoplatelets. She is a CNRS researcher since 2016.

Using femtosecond optical spectroscopy to study the ultrafast dynamics in semiconductor nanomaterials: relaxation, recombination and coherences
Keywords: hot exciton relaxation, exciton-phonon interactions, electronic and vibrational coherences, pump-probe spectroscopy
Summary: Interaction of light with photoactive materials results in several dynamical processes that are essential to understand in order to develop performant optoelectronic devices based on light-energy conversion. In this lecture we will introduce two kinds of ultrafast optical spectroscopy tools that allow a deep investigation of the different processes occurring from a few tens of femtoseconds (10s 10-15 s) to a few nanoseconds: femtosecond transient absorption and two-dimensional electronic spectroscopy [1,2,3]. In particular, we will discuss the ultrafast hot exciton relaxation in colloidal semiconductor nanostructures and the effect of internal and external vibrational modes (phonon bottleneck effect, coupling with surface ligand vibrational modes, etc…) [4]. We will also introduce the notion of electronic and vibrational coherences and their potential role in efficient energy transfer, charge transfer & exciton dissociation [5,6].
[1] R. Berera, R. van Grondelle and J.T.M. Kennis, Ultrafast transient absorption spectroscopy: principles and application to photosynthetic systems. Photosynth. Res. 2009 101: 105-118.
[2] D.M. Jonas, Two-dimensional Femtosecond Spectroscopy, Annu. Rev. Phys. Chem. 2003, 54: 425-463.
[3] E. Cassette, J.C. Dean and G.D. Scholes, Two-Dimensional Visible Spectroscopy For Studying Colloidal Semiconductor Nanocrystals. Small 2016, 12: 2234-2244.
[4] C. Villamil Franco, G. Trippé-Allard, B. Mahler, C. Cornaggia, J.-S. Lauret, T. Gustavsson and E. Cassette, Exciton Cooling in 2D Perovskite Nanoplatelets: Rationalized Carrier-Induced Stark and Phonon Bottleneck Effects. J. Phys. Chem. Lett. 2022 13: 393-399.
[5] E. Cassette, R.D. Pensack, B. Mahler and G.D. Scholes, Room-temperature exciton coherence and dephasing in two-dimensional nanostructures. Nat. Commun. 2015 6:6086.
[6] C.A. Rozzi, S.M. Falke, N. Spallanzani, A. Rubio, E. Molinari, D. Brida, M. Maiuri, G. Cerullo, H. Schramm, J. Christoffer and C. Lienau, Quantum coherence controls the charge separation in a prototypical artificial light-harvesting system. Nat Commun. 2013 4: 1602.

Gregory Hartland
University of Notre Dame

Prof. Hartland obtained a Ph. D. from UCLA in 1991, and performed postdoctoral studies at the University of Pennsylvania before joining the Department of Chemistry and Biochemistry at the University of Notre Dame in 1994, where he is currently a Full Professor. Prof. Hartland is a Fellow of the AAAS, the American Chemical Society and the Royal Society of Chemistry, and is the Deputy Editor for the Journal of Physical Chemistry C.

Ultrafast Studies of Single Plasmonic Nanostructures
Keywords: plasmons, single particle, ultrafast, acoustic vibrations
Summary: Metal nanostructures display several types of resonances. In the visible and near-IR regions there are plasmon resonances that involve coherent motion of the electrons. In addition, the vibrational modes of metal nanostructures give rise to low frequency resonances in the gigahertz to terahertz range. These different resonances suffer energy losses from internal effects and from interactions with the environment. The goal of this talk is to describe the energy relaxation process due to the environment. Even though plasmons and acoustic vibrations arise from different physics, environmental damping is dominated by radiation of waves. The way the damping depends on the nanostructure size and the properties of the environment will be discussed, as well as examples of applications enabled by the control of radiation damping, such as the use of metal nanostructures as nanoscale mass balances.

Kareem Elsayad
Medical University of Vienna

Research of the Elsayad Lab centers on developing optical microscopy and spectroscopy approaches to better elucidate microscopic scale mechanical, structural, and dynamic properties of biological matter. These are used to provide insight into their anatomical, functional, and potential medical relevance. They work on diverse model organisms and human donor samples, and collaborate with clinics to explore the translational potential.

Pascal Ruello
Professor at Le Mans University and researcher at the Institute of Molecules Materials UMR CNRS 6283, Le Mans University, France

Pascal Ruello, Professor of Physics, is specialist in solid states physics and ultrafast phenomena in condensed matter (time-resolved spectroscopies of electrons and phonons). He contributed to the description and the evaluation of the physical mechanisms of ultrafast photogeneration of coherent acoustic phonons in solids, including semiconductors and ferroic materials for instance. He also contributed to the development of nanoscale imaging of transparent materials with time-resolved Brillouin light scattering spectroscopy.

Ultrafast phonon generation and detection in solids : a combination of optical, THz and X-ray light pulses
Keywords: Time-resolved spectroscopy, picosecond acoustics, light-induced strain phenomena
Summary: Phonon time-resolved spectroscopies born in the eighties have opened the route for the control of lattice dynamics in bulk materials and nanostructures including acoustic (GHz-THz) [1-4] and optical (Thz) [5] phonons. Among these time-resolved spectroscopies, picosecond acoustics has revealed important advantage for understanding the light-induced strain in solids [1-4], for the development of non-destructive testing of nanostructures and for submicrometer scale imaging in transparent materials [6] based on the time-resolved Brillouin scattering [7]. In picosecond acoustics, many experiments have been conducted with optical pump-probe scheme where the photon energy (pump and/or probe) is in the NIR-VIS-NUV range usually. With the advent of new time-resolved spectroscopies such as time-resolved X-ray diffraction [8] and THz spectroscopy [9] it appears now possible to envision new way to drive the motion in the matter and to probe the absolute ultrafast light-induced strain. In this lecture, after a general presentation of picosecond acoustics (generation/detection), I will present recent achievements where a combination of different light sources (visible, THz, RX) offers new opportunities to understand the physics of ultrafast phonon generation and detection in different materials such as metals [10], multiferroics [11] and phase change materials [12] for instance.
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[3] V. Gusev, A. Karabutov, Laser Optoacoustics, AIP, New York, 1993
[4] P. Ruello, V. E. Gusev, Ultrasonics 56, 21-35 (2015)
[5] R. Merlin, Sol. State. Comm. 102, 207–220 (1997)
[6] V.E. Gusev, P Ruello, Appl. Phys. Rev. 5 (3), 031101 (2018)
[7] C. Thomsen et al, Opt. Comm. 60, 55-58 (1986)
[8] A. Lindenberg et al, Phys. Rev. Lett. 84, 111 (2001)
[9] T. Kampfrath et al, Nat. Photon., 7, 680–690 (2013)
[10] A. Levchuk et al Phys. Rev. B 101 (18), 180102 (2020)
[11] V. Juvé et al, Phys. Rev. B 102, 220303(R) (2020)
[12] R. Gu et al, Phys. Rev. Appl. 16 (1), 014055 (2021)

Luc Thévenaz
Ecole Polytechnique Fédérale de Lausanne (EPFL)

Luc Thévenaz leads a research group at EPFL (Group for Fibre Optics) involved in photonics, namely fibre optics and optical sensing. Research topics include Brillouin-scattering fibre sensors, slow and fast light, nonlinear fibre optics and laser applications in gases. He also contributed to the development of distributed fibre sensing by proposing innovative concepts pushing beyond barriers. Prof. Thévenaz chaired the International Conference on Optical Fibre Sensors, is co-Executive Editor-in-Chief of Nature Light: Science & Applications and is an OSA and IEEE Fellow.

Stimulated Brillouin Scattering in optical fibres: fundamentals and applications to sensing, slow & fast light and optical signal processing
Keywords: Brillouin scattering, optical fibre, distributed fibre sensing, slow & fast light
Summary: Coupling 2 lightwaves is only possible through the intercession of matter and acoustic vibrations turn out to offer the further advantage to make this coupling coherent. These material vibrations are stimulated by intensity-modulated lightwaves and their effect is detected through a phase-modulation on a distinct lightwave, so that the system is entirely activated and probed using light. We shall present the fundamentals of such a process designated as stimulated Brillouin scattering and it will be shown that an intense distributed amplification of light can be obtained. Since the acoustic properties are strongly dependent on the nature and the response of the hosting material, sensors based on such interactions can be made distributed and show remarkable and unique performance. Finally, such interactions can be efficiently exploited to actively modify the group velocity in a medium (slow & fast light), as well as to implement all-optical signal processing and coherent optical memories.
1. Advanced Fiber Optics: Concepts and Technology. Thévenaz, Luc, éd. Engineering Sciences. Lausanne, Switzerland: EPFL Press, distributed by CRC Press, 2011.
2. Motil, Avi, Arik Bergman, et Moshe Tur. State of the art of Brillouin fiber-optic distributed sensing. Optics & Laser Technology 78, Part A (2016): 81 103.
3. Thévenaz, Luc. Slow and fast light in optical fibres. Nat Photon 2, no 8 (2008): 474 81.
4. Santagiustina, Marco, Sanghoon Chin, Nicolay Primerov, Leonora Ursini, and Luc Thévenaz. All-optical signal processing using dynamic Brillouin gratings. Sci. Rep. 3 (3 avril 2013): 1594.

Daniel Lanzillotti Kimura
Centre de Nanosciences et de Nanotechnologies (C2N) – CNRS – Université Paris Saclay

Daniel Lanzillotti Kimura obtained his Ph.D. in 2009 from both the Instituto Balseiro in Argentina and the Institute of Nanosciences in Paris. His field of research is nanophononics and nanomechanics. He was a postdoctoral researcher in the Bariloche Atomic Center in Argentina, the University of California at Berkeley in the USA, and the Laboratory for Photonics and Nanostructures in France. Since 2015, he is a tenured researcher of the CNRS in France, and in 2016 he was awarded an ERC Starting Grant.

Optophononics: beyond the few GHz regime
Keywords: acoustic phonons, nanomechanics, optomechanics, nanocavities, nanophononics
Summary: Advances in material science and fabrication techniques enabled the fabrication of samples with nanometric dimensions where it is possible to confine photons and phonons (GHz-THz frequencies) in a single resonant cavity. In this lecture, I will describe the behavior of a plethora of devices able to control the interactions between light, sound, and charge at the nanoscale. I will introduce some strategies to generate, manipulate and detect ultra-high frequency acoustic phonons both in the time and spectral domains.
[1] O. Ortiz et al., “Topological optical and phononic interface mode by simultaneous band inversion,” Optica, vol. 8, no. 5, pp. 598–605, May 2021, doi: 10.1364/OPTICA.411945.
[2] M. Esmann et al., “Brillouin scattering in hybrid optophononic Bragg micropillar resonators at 300  GHz,” Optica, vol. 6, no. 7, pp. 854–859, juillet 2019, doi: 10.1364/OPTICA.6.000854.
[3] O. Ortiz et al., “Fiber-integrated microcavities for efficient generation of coherent acoustic phonons,” Appl. Phys. Lett., vol. 117, no. 18, p. 183102, Nov. 2020, doi: 10.1063/5.0026959.
[4] A. Rodriguez et al., “Fiber-based angular filtering for high-resolution Brillouin spectroscopy in the 20-300 GHz frequency range,” Opt. Express, vol. 29, no. 2, pp. 2637–2646, Jan. 2021, doi: 10.1364/OE.415228.

Eva Weig
Technical University of Munich

Eva Weig studied Physics and obtained her Ph.D. at the Ludwig-Maximilians University in Munich. After two years as a postdoctoral researcher at the University of California in Santa Barbara in the groups of Andrew Cleland and John Martinis, she returned to LMU Munich to lead the Nanomechanics group at the Chair of Jorg Kotthaus. In 2013, she was appointed a Professor of Experimental Physics at the University of Konstanz, Germany. Since 2020, she leads the Chair of Nano & Quantum Sensors at the Technical University of Munich.

Nanomechanical Systems
Keywords: Nanomechanics, NEMS
Summary: This lecture will focus on the resonant behavior of nanomechanical systems. These involve freely suspended nanostructures with discrete vibrational eigenmodes, such as, e.g., the flexural modes of a string or a membrane. Nanomechanical resonators are receiving an increasing amount of attention for a broad range of possible applications, ranging from practical sensing to fundamental challenges addressing the foundations of quantum mechanics. This lecture will give an overview over the field of nanomechanics, and highlight state of the art experiments.

Arnaud Arbouet

Arnaud Arbouet is a CNRS research director working at CEMES-CNRS (Toulouse, France) in the Nano-Optics and Nanomaterials for Optics group. He is working on the optical response and ultrafast dynamics of nanoscale systems with time-resolved optical and electron microscopies. He has developed a high-brightness ultrafast Transmission Electron Microscope and recently co-founded the CNRS-Hitachi joint laboratory for ultrafast Transmission Electron Microscopy.

Coherent Ultrafast Transmission Electron Microscopy: Applications to Nano-optics and Nanomechanics*
Keywords: Ultrafast Transmission Electron Microscopy, nano-optics, electron energy gains, acoustic vibrations
Summary: Nanosized systems have optical properties that can differ significantly from their bulk counterpart due to the existence of optical resonances such as surface plasmons in metallic nanoparticles or Mie modes in high refractive index nanostructures. These excitations have extremely short lifetimes (fs-ns) and pattern the optical near-field on subwavelength scales.
Ultrafast Transmission Electron Microscopes (UTEM) combining sub-picosecond temporal resolution and nanometer spatial resolution have emerged as unique tools for investigations at ultimate spatio-temporal resolution [1,2]. In this talk, I will report on the development of a high-brightness UTEM and discuss its potential in nano-optics and nanomechanics [3,4]. In particular, I will report on Electron Energy Gain Spectroscopy experiments performed in a UTEM that allow mapping the optical near-field at the nanometer scale and discuss the potential of electron diffraction and holography experiments performed with femtosecond electron pulses to explore the vibrational dynamics of nanoscale systems.
[1] 4D Electron Microscopy, Imaging in Space and Time, 2009
Ahmed H Zewail and John M Thomas (Cambridge)
[2] Ultrafast Transmission Electron Microscopy : fundamentals, instrumentation and applications
Arnaud Arbouet, Giuseppe M. Caruso, Florent Houdellier
Advances in Imaging and Electron Physics, Advances in Electronics and Electron Physics, 207, Elsevier, 2018, 1076-5670, 2018
[3] Development of a high brightness ultrafast Transmission Electron Microscope based on a laser-driven cold field emission source
F. Houdellier, Giuseppe Mario Caruso, Sébastien Weber, Mathieu Kociak and Arnaud Arbouet
Ultramicroscopy, 186, 128-138, 2018
[4] High brightness ultrafast transmission electron microscope based on a laser-driven cold-field emission source: principle and applications
G.M. Caruso, F Houdellier, S Weber, M Kociak, A Arbouet
Advances in Physics: X 4 (1), 1660214, 2019

Valentina Giordano
CNRS, Institut Lumière Matière, UMR 5306, Villeurbanne

Former Beamline Scientist at the Inelastic X ray scattering beamline of ESRF, VG has been recruited at the CNRS in 2011. Expert in phonon dynamics, the focus of her research is the understanding pf phonon dynamics and thermal transport in amorphous materials, complex crystals and nanostructured materials. Since 8 years she has launched a research line on nanocomposite and nanophononic materials, where she investigates phonons using top of the art techniques at large scale facilities, such as synchrotrons, nuclear reactors and Free Electron Lasers, as well as laboratory spectroscopy techniques.

Inelastic x-ray and neutron scattering for investigating phonon dynamics and thermal transport
Summary: Thermal transport in materials is assured by electrons and atomic vibrations, so that in semiconductors and insulators these latter are the dominant heat carriers. The quasi-particle of the atomic vibrations, the phonon, is characterized by a wavelength l and a velocity v, carrying an energy ћw=2pv/l over the distance travelled during its lifetime, before undergoing a scattering process. Understanding thermal transport requires then the knowledge of the individual properties of the phonons and the understanding of the scattering mechanisms that they undergo and which limit their lifetime.
Phonons responsible for thermal transport at room temperature are usually the ones with THz energies and sub-nanometric wavelengths. These phonons are only accessible in a large phase space by inelastic X ray and neutrons scattering techniques, which are thus the tools of choice for getting such microscopic knowledge. Other, laser-based, techniques are needed to access phonons at lower energies, with wavelengths in the tens and hundreds of nanometers. A short panoramic will be given, with a focus on X ray and neutrons inelastic scattering, illustrating their limits and advantages and how such experiments can allow to understand thermal transport in a variety of systems.

Lukas Jacob
NanoPhotonics Centre, Cavendish Laboratories, University of Cambridge, UK

Lukas Jakob is a final year PhD candidate at the NanoPhotonics Centre at the University of Cambridge supervised by Prof. Jeremy J. Baumberg. His research is focused on exploring molecular vibrations in plasmonic nanocavities with ultrafast surface-enhanced Raman scattering. He completed his undergraduate studies in Nanoscience at the University of Tübingen, Germany.

Molecular Optomechanics in Plasmonic Nano- and Picocavities
Keywords: Nanocavity, picocavity, nanoparticle-on-mirror, SERS, molecular optomechanics
Summary: Extreme plasmonic confinement in self-assembled nanoparticle-on-mirror structures allows experimental access to molecular vibrations of <100 molecules. The intense optical fields in the cavity excite vibrations and unveil nonlinear effects such as vibrational pumping, optomechanical coupling and collective vibrations interrogated via surface-enhanced Raman scattering (SERS). Further enhancement is produced by atomic protrusions of the metal (‘picocavities’) focusing the light in volumes <1 nm3 and probing a single molecule. This lecture will introduce the optical properties of the nanoparticle-on-mirror structure and its various applications in SERS. In particular, we will explore the interaction of light in the cavity with molecular vibrations described by molecular optomechanics.
Extreme nanophotonics from ultrathin metallic gaps, Nature Materials 18, 668 (2019); DOI: 10.1038/s41563-019-0290-y
Pulsed molecular optomechanics in plasmonic nanocavities:..., PRX 8, 011016 (2018); DOI : 10.1103/PhysRevX.8.011016
Single-molecule optomechanics in picocavities, Science 354, 726 (2016); DOI: 10.1126/science.aah5243

Bernard Perrin
Institute of Nanosciences in Paris UMR CNRS 7588, Sorbonne University, France

Bernard Perrin, is an emeritus CNRS research director who worked on nonlinear acoustics, phonon interactions and phonon transport. He contributed to the development of many aspects in the field of picosecond acoustics. Among others, he worked on the design, the realization and the use of emitters and detectors of coherent acoustic waves in the Terahertz range. He successfully demonstrated that these new devices could be used to measure the mean free path of such ultra-high coherent phonons wave packets.

Using picosecond ultrasonics to study sound absorption and phonon lifetimes in the GHz to THz frequency range
Keywords: picosecond acoustics, Phonon-phonon interaction, phonon mean free path, time resolved Brillouin scattering
Summary: Picosecond ultrasonics is a technique that scans a wide frequency spectrum from a few GHz to THz depending on the systems, materials and configurations. However, the penetration depth of acoustic waves is not very well-known in this frequency range although this information would be very useful for applications involving high frequency acoustic waves or vibrations such as magneto acoustics [1], phonon imaging, optomechanics. Picosecond acoustics offers many opportunities to achieve accurate measurements of this quantity. During this lecture, I will give an overview about the studies and measurements of attenuation of longitudinal acoustic phonons in different systems (thin films [2-3], bulk materials [4-7], acoustic cavities ), different materials (semi-conductors[6,8,9], glasses [2,10], quasicrystals [4], polymers) and using different experimental configurations (echoes, time-resolved Brillouin scattering [12], resonant excitation of cavities [13]…).
1. Scherbakov, AV, et al. Phys. Rev. Lett. 102, 117204 (2010)
2. T.C. Zhu, H.J. Maris, J. Tauc, Phys. Rev. B 44, 4281 (1994)
3. Hao H-Y, Maris H.J., Phys. Rev. B63, 224301 (2001)
4. J.-Y. Duquesne, B. Perrin, Phys. Rev. B68, 134205 (2003)
5. Daly B,. et al. Phys. Rev. B80, 174112 (2009)
6. R. Legrand, et al. Phys. Rev. B95, 014304 (2017)
7. G. Rozas, et al. Phys. Rev. Lett. 102, 015502 (2009)
8. Y-C Wen, et al. Appl. Phys. Lett. 99, 051913 (2011)
9. T.-H. Chou, et al. Phys. Rev. B 100 (2019) 094302
10. W. Chen, et al. Phil. Mag. B70, 368 (1994)
11. P. Emery, A. Devos, Appl. Phys. Lett. 89, 191904 (2006)
12. P. I. Bozovic, et al. Phys. Rev. B 69, 132503 (2004)
13. C. Lagoin, et al. Phys. Rev. B. Rapid Communications, B99, 060101 (2019)

Francesca Palombo
University of Exeter, UK

I am Associate Professor of Biomedical Spectroscopy in the School of Physics and Astronomy and affiliate investigator of the Living Systems Institute (LSI) at the University of Exeter, UK. My research is focused on developments of Brillouin, Raman and FTIR spectroscopy methods for applications to biology and medicine. I am interested in physical and chemical aspects of biological systems at a molecular level, and impairments in disease, e.g. cancer, dementia.

High frequency biomechanics probed by Brillouin spectroscopy
Keywords: biophotonics, acoustics, light scattering, biomolecules, elastic moduli
Summary: Mechanical properties of biological systems such as cells and tissues are critical to their function, and impairment can lead to disease occurrence. Macroscopic elastic moduli provide a good description of the function of tendons and bones. However, the microscopic realm remains largely elusive due to the lack of experimental tools to target that domain in a non-destructive and viable manner. Brillouin light scattering (BLS) spectroscopy can fill that gap by giving access to a new spatio-temporal regime which is complementary to that of Raman and FTIR based techniques. It provides information on the propagation of spontaneous acoustic waves at high frequency probing viscous and elastic properties on a micro-scale in a non-destructive and contactless manner. This lecture will cover emerging BLS spectroscopy applications to the biomedical sciences.
Bailey et al. Science Advances, 6: abc1937 (2020)
Palombo and Fioretto, Chemical Reviews, 119: 7833-7847 (2019)
Palombo et al. Analyst, 139: 729-733 (2014)
Palombo et al. Journal of the Royal Society Interface, 11: 101 (2014)

Inès Ghorbel
Thales Research & Technology

Inès Ghorbel holds a PhD. from Université Paris Saclay in optomechanics. She has gained expertise in oscillators and conducted theoretical and experimental analysis of nanosized optomechanical oscillators. Currently, she is a research engineer at Thales Research and Technology, France where she continues to work on optomechanical oscillators, alongside other research fields such as photonic crystal quantum photon sources and fiber sensors.

Review on some applications of opto-mechanics
Keywords: Cavity optomechanics, sensors, oscillators
Summary: Bringing a product to the market from fundamental research is hazardous path and interaction between academic research and private sector might help that. In this talk, through the example of research in the field of cavity optomechanics and Brillouin and Rayleigh scattering at Thales Research and Technology, we will explore some applications of optomechanics. By comparing the state of the art with the expected specifications, we shall consider the way ahead to make applied optomechanics come true.
I. Ghorbel, F. Swiadek, R. Zhu, D. Dolfi, G. Lehoucq, A. Martin, G. Moille, L. Morvan, R. Braive, S. Combrié, and A. De Rossi , "Optomechanical gigahertz oscillator made of a two photon absorption free piezoelectric III/V semiconductor", APL Photonics 4, 116103 (2019)