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Oxygenation monitoring of deep biological tissues with a bedside non-invasive method is still a crucial issue that is not resolved in routine clinics. It is particularly important in several major clinical applications with significant societal and financial implications such as the management of severe traumatic brain injury or stroke, the monitoring of hemodynamic parameters during or after birth or the post-operative monitoring after breast reconstruction surgery. However, the chances of recovery are directly proportional to the rapidity of diagnosis and subsequent remedial treatment. We propose an optical Time-Resolved probe, which monitor noninvasively the level of oxygenation in deep tissues. Our solution combines a measurement device, a stethoscope-type probe and an analysis software that provides biomarkers of tissue oxygenation. It is validated on a cohort of 15 pigs with the detection and identification of all arterial and venous events induced by the experiments’ protocol. We implement two analysis methods– one is real-time and aim at detecting and identifying the occlusion; it is based on a Time-Resolved windowing approach. The other post-processes the data and focuses on the quantification purpose; it is based on a tomographic approach.

We report a method for deriving the absolute value of absorption coefficients at depth in bilayered media. The method was simplified from that of time-resolved diffuse optical tomography (TR-DOT) into one dimension to validate and set up the main parameters with the help of simulations, and to test it in an easy preclinical model. The method was applied to buried flaps as used in reconstructive surgery, and absolute chromophore concentrations in the flap and in the upper (skin and fat) layer were derived. The encouraging results obtained lay a foundation for developing more complex multidimensional models.

This work deals about the study of coherence between triple photon beams generated by a third order non linear interaction. A protocol, based on the study of the field arising from sum-frequency of the triplet fields in a non linear crystal, was proposed. A theoretical model, in the quantum formalism, was developed, leading to an exhaustive research of the potential signature of the correlations. All the possible schemes were studied : triple fields generation from parametric fluorescence or from stimulated interaction, and recombination of two or three of the triple fields. The experiments we led, i.e. the bi-stimulated non linear generation and the recombination of the so-born fields, agree with our theoretical model and put into light the correlations hiding in this highly stimulated regime, since these correlations lie in the quantum fluctuations of the fields operators. The theoretical calculations predicts a strong correlations signature when the fields are generated from parametric fluorescence, and a weaker one in the case of a generation mono-stimulated., Ce travail porte sur l'étude de la cohérence entre champs triplets générés par interaction non linéaire d'ordre trois. Un protocole indirect, basé sur l'étude du champ issu de la somme de fréquences des champs triplets dans un cristal non linéaire a été envisagé. Une modélisation théorique en formalisme quantique de l'évolution des champs, de leur génération à leur recombinaison, a été développée, donnant lieu à une recherche exhaustive des signatures de corrélations susceptibles d'émerger de notre protocole. Les expériences menées, à savoir la génération non linéaire bi-stimulée et la recombinaison des champs ainsi générés, sont en accord avec notre modèle théorique et permettent de mettre en évidence le masquage des corrélations entre les champs dans ce régime fortement injecté, ces corrélations étant contenues dans les fluctuations quantiques, alors négligeables, des opérateurs champs. Le calcul théorique prédit une signature de corrélations fortes entre les photons triplets dans la cas d'un génération par fluorescence paramétrique, et plus faible dans le cas d'une génération mono-stimulée.

This work deals about the study of coherence between triple photon beams generated by a third order non linear interaction. A protocol, based on the study of the field arising from sum-frequency of the triplet fields in a non linear crystal, was proposed. A theoretical model, in the quantum formalism, was developed, leading to an exhaustive research of the potential signature of the correlations. All the possible schemes were studied : triple fields generation from parametric fluorescence or from stimulated interaction, and recombination of two or three of the triple fields. The experiments we led, i.e. the bi-stimulated non linear generation and the recombination of the so-born fields, agree with our theoretical model and put into light the correlations hiding in this highly stimulated regime, since these correlations lie in the quantum fluctuations of the fields operators. The theoretical calculations predicts a strong correlations signature when the fields are generated from parametric fluorescence, and a weaker one in the case of a generation mono-stimulated.; Ce travail porte sur l'étude de la cohérence entre champs triplets générés par interaction non linéaire d'ordre trois. Un protocole indirect, basé sur l'étude du champ issu de la somme de fréquences des champs triplets dans un cristal non linéaire a été envisagé. Une modélisation théorique en formalisme quantique de l'évolution des champs, de leur génération à leur recombinaison, a été développée, donnant lieu à une recherche exhaustive des signatures de corrélations susceptibles d'émerger de notre protocole. Les expériences menées, à savoir la génération non linéaire bi-stimulée et la recombinaison des champs ainsi générés, sont en accord avec notre modèle théorique et permettent de mettre en évidence le masquage des corrélations entre les champs dans ce régime fortement injecté, ces corrélations étant contenues dans les fluctuations quantiques, alors négligeables, des opérateurs champs. Le calcul théorique prédit une signature de corrélations fortes entre les photons triplets dans la cas d'un génération par fluorescence paramétrique, et plus faible dans le cas d'une génération mono-stimulée.