Two-photon excitation microscopy is a fluorescence imaging technique that allows imaging of living tissue up to about one millimeter in thickness, with 0.64 μm lateral and 3.35 μm axial spatial resolution. Unlike traditional fluorescence microscopy, in which the excitation wavelength is shorter than the emission wavelength, two-photon excitation requires simultaneous excitation by two photons with longer wavelength than the emitted light. Two-photon excitation microscopy typically uses near-infrared (NIR) excitation light which can also excite fluorescent dyes. However, for each excitation, two photons of NIR light are absorbed. Using infrared light minimizes scattering in the tissue. Due to the multiphoton absorption, the background signal is strongly suppressed. Both effects lead to an increased penetration depth for this technique. Two-photon excitation can be a superior alternative to confocal microscopy due to its deeper tissue penetration, efficient light detection, and reduced photobleaching.
An optical frequency multiplier is a nonlinear optical device in which photons interacting with a nonlinear material are effectively "combined" to form new photons with greater energy, and thus higher frequency. Two types of devices are currently common: frequency doublers, often based on lithium niobate (LN), lithium tantalate (LT), potassium titanyl phosphate (KTP) or lithium triborate (LBO), and frequency triplers typically made of potassium dihydrogen phosphate (KDP). Both are widely used in optical experiments that use lasers as a light source.
The Institut d'optique Graduate School, nicknamed SupOptique or IOGS, is one of the most prestigious French Grandes Ecoles and the leading French grande école in the field of Optics and its industrial and scientific applications, and a graduate school of the prestigious Paris-Saclay University and ParisTech.
Second-harmonic generation is a nonlinear optical process in which two photons with the same frequency interact with a nonlinear material, are "combined", and generate a new photon with twice the energy of the initial photons, that conserves the coherence of the excitation. It is a special case of sum-frequency generation, and more generally of harmonic generation.
The Berthold Leibinger Zukunftspreis is an international award for excellent research on the application or generation of laser light. Since 2006 it is biennially awarded by the German non-profit foundation Berthold Leibinger Stiftung with an amount of 50,000 euros, not earmarked.
Second-harmonic imaging microscopy (SHIM) is based on a nonlinear optical effect known as second-harmonic generation (SHG). SHIM has been established as a viable microscope imaging contrast mechanism for visualization of cell and tissue structure and function. A second-harmonic microscope obtains contrasts from variations in a specimen's ability to generate second-harmonic light from the incident light while a conventional optical microscope obtains its contrast by detecting variations in optical density, path length, or refractive index of the specimen. SHG requires intense laser light passing through a material with a noncentrosymmetric molecular structure, either inherent or induced externally, for example by an electric field.
Aimé Auguste Cotton was a French physicist known for his studies of the interaction of light with chiral molecules. In the absorption bands of these molecules, he discovered large values of optical rotatory dispersion (ORD), or variation of optical rotation as a function of wavelength, as well as circular dichroism or differences of absorption between left and right circularly polarized light.
Thomas Ebbesen is a Franco-Norwegian physical chemist and professor at the University of Strasbourg in France, known for his pioneering work in nanoscience. He received the Kavli Prize in Nanoscience “for transformative contributions to the field of nano-optics that have broken long-held beliefs about the limitations of the resolution limits of optical microscopy and imaging”, together with Stefan Hell, and Sir John Pendry in 2014.
Paul Bruce Corkum is a Canadian physicist specializing in attosecond physics and laser science. He holds a joint University of Ottawa–NRC chair in Attosecond Photonics. He is one of the students of strong field atomic physics, i.e. atoms and plasmas in super-intense laser fields.
The term chiral describes an object, especially a molecule, which has or produces a non-superposable mirror image of itself. In chemistry, such a molecule is called an enantiomer or is said to exhibit chirality or enantiomerism. The term "chiral" comes from the Greek word for the human hand, which itself exhibits such non-superimposeability of the left hand precisely over the right. Due to the opposition of the fingers and thumbs, no matter how the two hands are oriented, it is impossible for both hands to exactly coincide. Helices, chiral characteristics (properties), chiral media, order, and symmetry all relate to the concept of left- and right-handedness.
A liquid-crystal laser is a laser that uses a liquid crystal as the resonator cavity, allowing selection of emission wavelength and polarization from the active laser medium. The lasing medium is usually a dye doped into the liquid crystal. Liquid-crystal lasers are comparable in size to diode lasers, but provide the continuous wide spectrum tunability of dye lasers while maintaining a large coherence area. The tuning range is typically several tens of nanometers. Self-organization at micrometer scales reduces manufacturing complexity compared to using layered photonic metamaterials. Operation may be either in continuous wave mode or in pulsed mode.
Wide-field multiphoton microscopy refers to an optical non-linear imaging technique tailored for ultrafast imaging in which a large area of the object is illuminated and imaged without the need for scanning. High intensities are required to induce non-linear optical processes such as two-photon fluorescence or second harmonic generation. In scanning multiphoton microscopes the high intensities are achieved by tightly focusing the light, and the image is obtained by beam scanning. In wide-field multiphoton microscopy the high intensities are best achieved using an optically amplified pulsed laser source to attain a large field of view (~100 µm). The image in this case is obtained as a single frame with a CCD without the need of scanning, making the technique particularly useful to visualize dynamic processes simultaneously across the object of interest. With wide-field multiphoton microscopy the frame rate can be increased up to a 1000-fold compared to multiphoton scanning microscopy. Wide-field multiphoton microscopes are not yet commercially available, but working prototypes exist in several optics laboratories.
Anne-Marie Lagrange, born March 12, 1962 in the Rhône-Alpes region of France, is a French astrophysicist. Lagrange's work focuses on the research and study of extrasolar planetary systems. Lagrange is the holder of numerous scientific awards and honorary decorations, including Knight of the Legion of Honour and is a member of the French Academy of Sciences since 2013.
Isabelle Ledoux-Rak is a French physicist and Professor at the École Normale Supérieure Paris-Saclay, where she is director of the Quantum and Molecular Photonics Laboratory and coordinator of the Erasmus Mundus Master's degree. Her research interests focus on the study of the non-linear optical properties of molecules and nanomaterials.
The Strasbourg Institute of Material Physics and Chemistry is a joint research unit between the French National Center for Scientific Research (CNRS) and the University of Strasbourg. It was founded in 1987 and is located in the district of Cronenbourg in Strasbourg, France.
Philippe Sautet is a French chemist. He was elected to the French Academy of sciences on 30 November 2010. He was a research director at the CNRS and works in the chemistry laboratory of the École normale supérieure de Lyon where he devoted a large part of his scientific activity to molecular modelling. Now he is a professor at the University of California - Los Angeles.
Hyper–Rayleigh scattering Optical Activity, is a nonlinear optical physical effect whereby chiral scatterers convert light to higher frequencies via harmonic generation processes, in a way that the intensity of generated light depends on the chirality of the scatterers. "Hyper–Rayleigh scattering" is a nonlinear optical counterpart to Rayleigh scattering. "Optical activity" refers to any changes in light properties that are due to chirality.
Nathalie Picqué is a French physicist working at the Max Planck Institute of Quantum Optics in the field Frequency Combs, where she studies ultra-high resolution spectroscopy using ultrashort pulses of light combined with Fourier-transform spectroscopy to reveal the fine chemistry of samples, in particular in the mid-infrared, demonstrating resolving power in excess of 1,000,000,000,000.
Jeanne Crassous is a French chemist who is a Professor and Director of Research at the French National Centre for Scientific Research (CNRS). She leads the Marie Skłodowska-Curie Actions International Training Network HEL4CHIROLED.
Pascale Senellart is a French physicist who is a senior researcher at the French National Centre for Scientific Research and professor at the École Polytechnique. She has worked on quantum light sources and semiconductor physics. She was awarded the CNRS Silver Medal in 2014, made Fellow of The Optical Society in 2018, and elected member of the French Academy of Sciences in 2022.
