Search results for "Photonique"
showing 10 items of 23 documents
Automatic measurement of wood fiber orientation and knot detection using an optical system based on heating conduction.
2015
In this paper, a new approach to computing the deviation of wood grain is proposed. To do this, the thermal conduction properties of timber are used (higher conduction in the fiber direction). Exciting the surface of the wood with a laser and capturing the thermal conduction using a thermal camera, an ellipse can be observed. Using a method similar to the tracheid effect, it is possible to extract information from this ellipse, such as the slope of grain and the presence of knots. With this method it is therefore possible to extend the mechanical model (assessing the mechanical properties of timber) to take certain singularities into account. Using this approach, the slope of grain can be e…
Development of ultra-fast thulium-doped fiber lasers - Prospects for 2μm-nanophotonics.
2021
Developing highly coherent pulsed sources around the 2 µm wavelengthhas been a particularly dynamic field of research in the last couples of years,due to its numerous applications. In optical telecommunication, the wavelength rangearound 2 µm is one of the most promising solutions to increase the transmission capacitypast the current technological bottleneck. In this context, passively mode-lockedfiber lasers appear as a high potential solution for cheap laser sources, due to their veryhigh coherence and intrinsic compatibility with telecommunication systems.Passively mode-locked fiber lasers at 1,55 µm and their ultrafast dynamics is oneof the specialty of the ICB laboratory, and the aim i…
Génération et détection d'électrons chauds dans des dispositifs plasmoniques
2021
Hot carrier-based devices are quite promissing for ultrafast photodetection and toset off enhanced physicochemical reactions. Controlling their generation at the nanoscale within plasmonic devices is a key for the future development of hybrid hot carriers technologies. Indeed, Surface PlasmonPolaritons (SPPs) can be exploited to confine light and enhance the number of excited hot carriers. We aim at studying the excitation and dynamics of hot carriers, enhanced by plasmonics, with two different approaches.In a first approach, we aim at controlling the delocalized generation of hot carriers by a propagative SPP. A plasmonic waveguide with a grating coupler is employed. Hot electrons are indi…
Generation and characterization of T40/A5754 interfaces with lasers
2014
Laser-induced reactive wetting and brazing of T40 titanium with A5754 aluminum alloy with 1.5 mm thickness was carried out in lap-joint configuration, with or without the use of Al5Si filler wire. A 2.4 mm diameter laser spot was positioned on the aluminum side to provoke spreading and wetting of the lower titanium sheet, with relatively low scanning speeds (0.1 to 0.6 m/min). Process conditions did not play a very significant role on mechanical strengths, which were shown to reach 250-300 N/mm on a large range of laser power and scanning speeds. In all cases considered, the fracture during tensile testing occurred next to the TiAl3 interface, but in the aluminum fusion zone. In a second st…
Polymer-metal plasmonic waveguide : passive and active components for integrated photonics
2009
Dielectric loaded surface plasmon polariton waveguides (DLSPPWs) enable transmission at a sub-wavelength scale of both electrical and plasmonic (optical waves at the interface between a metal and a dielectric) signals in the same circuitry. Moreover, the use of a polymer as the dielectric load enables the functionalization of DLSPPWs. Therefore, this configuration is of great interest for integrated photonic applications. However, DLSPPWs suffer strong losses due to dissipation into the metal film. We address here the possibility of compensating the losses using a configuration analogous to an optical amplifier. We first set theoretical (effective index model), numerical (differential metho…
chalcogenide materials for nonlinear integreted optics in mid-infrared
2019
Elaboration and characterization of new compositions of chalcogenide materials exhibiting nonlinear effects for integrated optic applications and fabrication of low-loss waveguides.
Optical frequency domain reflectometer distributed sensing using microstructured pure silica optical fibers under radiations
2016
International audience; We investigated the capability of micro-structured optical fibers to develop multi-functional, remotely-controlled, Optical Frequency Domain Reflectometry (OFDR) distributed fiber based sensors to monitor temperature in nuclear power plants or high energy physics facilities. As pure-silica-core fibers are amongst the most radiation resistant waveguides, we characterized the response of two fibers with the same microstructure, one possessing a core elaborated with F300 Heraeus rod representing the state-of-the art for such fiber technology and one innovative sample based on pure sol-gel silica. Our measurements reveal that the Xray radiations do not affect the capaci…
Evaluation of Distributed OFDR-Based Sensing Performance in Mixed Neutron/Gamma Radiation Environments
2017
We report the study of a radiation resistant single mode optical fiber doped with fluorine exposed to mixed neutron and $\gamma $ -radiation up to $10^{17}$ n/cm2 fluence and >2 MGy dose to evaluate its performances when used as the sensing element of a distributed Optical Frequency Domain Reflectometry (OFDR). The use of complementary spectroscopic techniques highlights some differences between the responses of solely $\gamma $ -radiation (10 MGy) or mixed neutron and $\gamma $ ( $10^{17}$ n/cm $^{2}+>2$ MGy) irradiated samples. Those differences are linked to the defect generation rather than to structural changes of the ${a}$ -SiO2 host matrix. We show that a modification of the refracti…
Coating impact and radiation effects on optical frequency domain Reflectometry fiber-based temperature sensors
2015
International audience; Temperature response of radiation-tolerant OFDR-based sensors is here investigated, with particular attention on the impact of coating on OFS. By performing consecutive thermal treatments we developed a controlled system to evaluate the performances of our distributed temperature sensor and to estimate the radiation impact. We show an important evolution of the temperature coefficient measurements with thermal treatments for non-irradiated fiber and that the amplitude of this change decreases increasing radiation dose. As final results, we demonstrate that sensor performances are improved if we performed a pre-thermal treatment on the fiber-based system permitting to…
Contribution à l'étude de la formation des images optiques en microscopie champ proche optique: effet de la sonde en deux dimensions
2004
This work consists in the development of a theoretical tool for the purpose to undertake numerical simulations able to take into account the coupling between the probe and the object. The first part, concerns the combination of the differential method and the algorithms T and S, to overcome numerical problems which appear in the cases where the size of system (probe - object) is more realistic. The developed global model is two-dimensional and applied in polarization TE under the normal diffraction condition. We have used the developed model to study the formation of optical image by monomodes and multimodes probes. The obtained optical images at constant height, have allowed us to study th…