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International audience; Fiber-based supercontinuum (SC) generation has been a subject of intense interest over the last decade, with a significant impact on both basic science and industry. New uses for SC fiber sources are constantly emerging due to their unique properties that combine high brightness, visible to mid-infrared (MIR) wavelength coverage, fiber delivery, and single-mode output. Recent years have seen significant progress in overcoming the current shortcomings of SC sources in terms of wavelength coverage towards the 2 to 20 mu molecular fingerprint mid-infrared (MIR) region and in the ultraviolet (UV) down to 100 nm, while also improving stability, noise, coherence, power density, and robustness. In this talk, we will review all the recent advances in supercontinuum generation in a range of specialty optical fibers including: fluoride, chalcogenide, telluride, and silicon-core fibers for the MIR; UV-grade silica fibers and gas-filled hollow-core fibers for the UV range; and all-normal dispersion fibers for ultra-low noise coherent SC generation. Significant developments have been made in reaching target UV and MIR wavelength ranges, and the fiber SC has matured considerably to become a truly disruptive technology able to meet a range of societal and industrial challenges.

We report online measurement of water vapor temperature and concentration in a high temperature industrial boiler using a broadband lidar employing a supercontinuum laser covering the ro-vibrational absorption spectrum of water molecules at 1.2 – 1.6 μm.

International audience

International audience; In contrast with direct measurement methods, correlation imaging measures the correlation function between the intensity emitted by a light source and the total (integrated) intensity transmitted (or reflected) by an ob- ject, such that the image can be constructed without the object to be actually seen. The essential nature of such “ghost imaging” lies in the mutual spatial correlation of the two beams, and the image can be simply obtained by summing all of the probing patterns, each weighted by the integrated signal from the detector. Here, we demonstrate for the first time ghost imaging in the spectral domain using a light source with shot- to-shot random spectral fluctuations. The advantage of the correlation approach is that it only detects the to- tal integrated signal after the object and thus can be in principle very sensitive even in low light conditions or in spectral regions where no fast detector exists. It is also inherently insensitive to any perturbation occurring between the object and the detector.

Dissipative solitons are remarkable localized states of a physical system that arise from the dynamical balance between nonlinearity, dispersion and environmental energy exchange. They are the most universal form of soliton that can exist in nature, and are seen in far-from-equilibrium systems in many fields including chemistry, biology, and physics. There has been particular interest in studying their properties in mode-locked lasers producing ultrashort light pulses, but experiments have been limited by the lack of convenient measurement techniques able to track the soliton evolution in real-time. Here, we use dispersive Fourier transform and time lens measurements to simultaneously measure real-time spectral and temporal evolution of dissipative solitons in a fiber laser as the turn-on dynamics pass through a transient unstable regime with complex break-up and collision dynamics before stabilizing to a regular mode-locked pulse train. Our measurements enable reconstruction of the soliton amplitude and phase and calculation of the corresponding complex-valued eigenvalue spectrum to provide further physical insight. These findings are significant in showing how real-time measurements can provide new perspectives into the ultrafast transient dynamics of complex systems., See also M. Narhi, P. Ryczkowski, C. Billet, G. Genty, J. M. Dudley, Ultrafast Simultaneous Real Time Spectral and Temporal Measurements of Fibre Laser Modelocking Dynamics, 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference, paper EE-3.5 (2017)

International audience; Using a parametric temporal magnifier system, we report for the first time on the direct temporal measurement of rogue waves and breather-like structures arising from spontaneous modulation instability.

International audience

International audience; We experimentally measure, for the first time, the secondorder temporal coherence of supercontinuum pulses from the time-resolved interference fringes observed at the output of a Michelson interferometer using cross-correlation frequency-resolved optical gating.

The ability to detect substances or molecules with high sensitivity and to image objects with high resolution plays an important role in our everyday life as well as in advances in understanding fundamental phenomena. Optical techniques are generally highly beneficial for this purpose as they are intrinsically remote, non-invasive and exhibit superior sensitivity and resolution. In this context, it is thus not surprising that a wide range of sensing and imaging techniques have been developed in the past decades and are continuously the subject intense research. The performance of these methods depends dramatically on the type of light source that is used and it is therefore essential to tailor the light source properties to the intended method of application.A spectral region which has recently attracted a wide interest is the mid-infrared corresponding to the molecular fingerprint region and the atmospheric transparency window. This in turn has triggered renewed research effort into adapting existing technique to this particular region of the electromagnetic spectrum including the light sources and detection schemes. This thesis reports novel, proof-of-concept, broadband optical sensing and imaging techniques in the infrared using supercontinuum light, a class of light sources with unique properties. The techniques are experimentally demonstrated and their performances discussed.Specifically, the thesis demonstrate incoherent broadband cavity enhanced absorp- tion spectroscopy in the mid-infrared wavelength range from 3000 to 3450 nm. Multi-component gas detection with sub-ppm accuracy is achieved in this range, which constitutes the widest continuous detection range for this technique in the mid-infrared.Cantilever-enhanced photoacoustic spectroscopy in the mid-infrared is also demonstrated for the first time in this thesis. The approach is broadband and allows for higher photoacoustic signal intensity and enhanced signal-to-noise ratio as compared to conventional systems that use back-body radiation sources. These results offer novel perspective for photoacoustic detection opening the door to sensitive broadband and compact analysers in the mid-infrared spectral region.Exploiting the shot-to-shot fluctuations of an incoherent supercontinuum and the recent progress in ultrafast real-time spectral measurement techniques, the thesis finally reports on a novel proof-of-concept correlation sensing and imaging method in the form of spectral-domain ghost imaging. The method is fast, scan-free, and offer new opportunities for remote sensing in scattering and absorbing media, or in spectral regions where sensitive detectors are lacking. Application of this technique to broadband spectroscopic measurements gases as well as for interferometric imaging of physical objects is demonstrated. One can legitimately expect that the work presented in this thesis will foster new ideas and developments for optical sensing and imaging.; Les méthodes de mesure optiques sont très performantes avec une sensibilité et une résolution généralement supérieure aux autres techniques, et elles possèdent aussi l’avantage d’être sans contact et non invasives. Cette thèse introduit plusieurs nouvelles techniques de détection optique et d'imagerie basées sur l’utilisation de sources super continuum dans l’infrarouge.Les propriétés uniques de ce type de source lumineuse, en particulier leur large bande spectrale combinée à une cohérence spatiale parfaite,permettent d’obtenir des performances supérieures en terme de résolution ou de sensibilité.Les techniques proposées sont expérimentalement démontrées et leurs performances caractérisées.La thèse démontre une technique de spectroscopie par absorption en cavité résonnante ainsi qu’une technique de spectroscopie par effet photo-acoustique, pour la première fois dans l’infrarouge moyen. La thèse introduit un nouveau concept de détection et d'imagerie par corrélations,équivalent à l’imagerie fantôme mais dans le domaine spectral, et son application à la spectroscopie par absorption ainsi qu'à la tomographie par cohérence optique d'objets physiques sont démontrées. Les techniques proposées et étudiées dans cette thèse ouvrent de nouvelles perspectives pour la détection sensible et l’imagerie dans l’infrarouge. De manière plus générale,les concepts introduits étant génériques, ils peuvent être étendus à d’autres régions du spectre électromagnétique et les travaux présentés sont amenés à stimuler de nouvelles idées et de nouveaux développements pour les techniques de détection et d'imagerie optiques.

The ability to detect substances or molecules with high sensitivity and to image objects with high resolution plays an important role in our everyday life as well as in advances in understanding fundamental phenomena. Optical techniques are generally highly beneficial for this purpose as they are intrinsically remote, non-invasive and exhibit superior sensitivity and resolution. In this context, it is thus not surprising that a wide range of sensing and imaging techniques have been developed in the past decades and are continuously the subject intense research. The performance of these methods depends dramatically on the type of light source that is used and it is therefore essential to tailor the light source properties to the intended method of application.A spectral region which has recently attracted a wide interest is the mid-infrared corresponding to the molecular fingerprint region and the atmospheric transparency window. This in turn has triggered renewed research effort into adapting existing technique to this particular region of the electromagnetic spectrum including the light sources and detection schemes. This thesis reports novel, proof-of-concept, broadband optical sensing and imaging techniques in the infrared using supercontinuum light, a class of light sources with unique properties. The techniques are experimentally demonstrated and their performances discussed.Specifically, the thesis demonstrate incoherent broadband cavity enhanced absorp- tion spectroscopy in the mid-infrared wavelength range from 3000 to 3450 nm. Multi-component gas detection with sub-ppm accuracy is achieved in this range, which constitutes the widest continuous detection range for this technique in the mid-infrared.Cantilever-enhanced photoacoustic spectroscopy in the mid-infrared is also demonstrated for the first time in this thesis. The approach is broadband and allows for higher photoacoustic signal intensity and enhanced signal-to-noise ratio as compared to conventional systems that use back-body radiation sources. These results offer novel perspective for photoacoustic detection opening the door to sensitive broadband and compact analysers in the mid-infrared spectral region.Exploiting the shot-to-shot fluctuations of an incoherent supercontinuum and the recent progress in ultrafast real-time spectral measurement techniques, the thesis finally reports on a novel proof-of-concept correlation sensing and imaging method in the form of spectral-domain ghost imaging. The method is fast, scan-free, and offer new opportunities for remote sensing in scattering and absorbing media, or in spectral regions where sensitive detectors are lacking. Application of this technique to broadband spectroscopic measurements gases as well as for interferometric imaging of physical objects is demonstrated. One can legitimately expect that the work presented in this thesis will foster new ideas and developments for optical sensing and imaging.; Les méthodes de mesure optiques sont très performantes avec une sensibilité et une résolution généralement supérieure aux autres techniques, et elles possèdent aussi l’avantage d’être sans contact et non invasives. Cette thèse introduit plusieurs nouvelles techniques de détection optique et d'imagerie basées sur l’utilisation de sources super continuum dans l’infrarouge.Les propriétés uniques de ce type de source lumineuse, en particulier leur large bande spectrale combinée à une cohérence spatiale parfaite,permettent d’obtenir des performances supérieures en terme de résolution ou de sensibilité.Les techniques proposées sont expérimentalement démontrées et leurs performances caractérisées.La thèse démontre une technique de spectroscopie par absorption en cavité résonnante ainsi qu’une technique de spectroscopie par effet photo-acoustique, pour la première fois dans l’infrarouge moyen. La thèse introduit un nouveau concept de détection et d'imagerie par corrélations,équivalent à l’imagerie fantôme mais dans le domaine spectral, et son application à la spectroscopie par absorption ainsi qu'à la tomographie par cohérence optique d'objets physiques sont démontrées. Les techniques proposées et étudiées dans cette thèse ouvrent de nouvelles perspectives pour la détection sensible et l’imagerie dans l’infrarouge. De manière plus générale,les concepts introduits étant génériques, ils peuvent être étendus à d’autres régions du spectre électromagnétique et les travaux présentés sont amenés à stimuler de nouvelles idées et de nouveaux développements pour les techniques de détection et d'imagerie optiques.