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See detailLaser control in open molecular systems: STIRAP and optimal control
Sugny, Dominique; Ndong, Mamadou; Lauvergnat, David et al

in Journal of Photochemistry and Photobiology A : Chemistry (2007), 190

Detailed reference viewed: 11 (0 ULiège)
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See detailLaser control in open quantum systems: preliminary analysis toward the Cope rearrangement control in methyl-cyclopentadienylcarboxylate dimer
Dive, Georges ULiege; Robiette, Raphaël; Chenel, Aurélie et al

in Theoretical Chemistry Accounts : Theory, Computation, & Modeling (2012), 131(6), 1236-1247

Detailed reference viewed: 17 (2 ULiège)
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See detailLaser cooling of atoms : Monte-Carlo wavefunction simulations
Chrétien, Renaud ULiege

Master's dissertation (2014)

The purpose of our master thesis is to present an original synthesis of various works dealing with the Monte-Carlo wavefunction (MCWF) method in quantum optics and its applications to laser cooling of ... [more ▼]

The purpose of our master thesis is to present an original synthesis of various works dealing with the Monte-Carlo wavefunction (MCWF) method in quantum optics and its applications to laser cooling of atoms with a particular focus on Doppler and Sisyphus cooling mechanisms. We introduce the MCWF method which is used to solve master equations describing the dynamics of open quantum systems in quantum optics. This method turns out to be much more efficient than a method based on the full integration of the density matrix. We perform laser cooling simulations in 1D both with a classical and a quantum treatment of the atomic centre-of-mass motion and investigate Doppler and Sisyphus cooling. Our numerical results turn out to be in very good agreement with those predicted by semiclassical theories, except for large detuning and/or low intensity laser where semiclassical theories fail. For such cases, our method provides a good alternative and predicts temperatures much larger than the recoil temperature. Finally, we also consider a classical treatment of the centre-of-mass motion and we compare the subsequent results with those obtained with a full quantum approach. [less ▲]

Detailed reference viewed: 35 (3 ULiège)
See detailLaser cooling of iron atoms
Huet, Nicolas ULiege

Doctoral thesis (2015)

The work presented in this thesis is dedicated to the development and implementation of a cold atom experiment which handles an atomic species that has not been cooled down so far: iron. The experiment ... [more ▼]

The work presented in this thesis is dedicated to the development and implementation of a cold atom experiment which handles an atomic species that has not been cooled down so far: iron. The experiment requires the use of two UV laser radiations (at 372 and 358 nm) that are frequency stabilized by means of saturation spectroscopy, an iron atomic beam, and a vacuum system, which we contributed to implement and characterize. In addition to this development, several spectroscopic studies were carried out in this thesis. By means of saturation spectroscopy, the hyperfine structure of the molecular-iodine R(90)3-10 transition at 716 nm was first studied following its involvement in the frequency stabilization of the 358-nm radiation. A spectroscopic study of the 358-nm Fe I cooling transition, which was totally unknown prior to this thesis, was also conducted using laser-induced fluorescence spectroscopy. With the same technique, a high accuracy measurement of the iron 358-nm transition frequency with respect to the molecular-iodine R(90)3-10 transition was performed. For this measurement, we implemented a particular configuration which allowed for the minimising of an important systematic error. The first laser cooling of iron is also reported. For this purpose, the Zeeman slowing technique was implemented following a particular two-laser scheme. To our knowledge, this Zeeman slower is the first of this kind. Furthermore, the complete characterization of the cold iron atomic beam produced at the output of the Zeeman slower was done, which allowed for an optimized loading of the magneto-optical trap. Finally, the creation of a cold cloud of iron atoms demonstrated the Zeeman slower ability to properly load an iron magneto-optical trap. [less ▲]

Detailed reference viewed: 160 (31 ULiège)
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See detailLaser cooling of Iron atoms
Huet, Nicolas ULiege; Krins, Stéphanie ULiege; Bastin, Thierry ULiege

Poster (2012, July 24)

We report on the first laser cooling of Iron atoms. Our laser cooling setup makes use of 2 UV laser radiation sent colinearly in a 0.8 m Zeeman slower. One laser is meant for optical pumping of the Iron ... [more ▼]

We report on the first laser cooling of Iron atoms. Our laser cooling setup makes use of 2 UV laser radiation sent colinearly in a 0.8 m Zeeman slower. One laser is meant for optical pumping of the Iron atoms from the ground state to the lowest energy metastable state. The second laser cools down the atoms using a quasi-perfect closed transition from the optical pumped metastable state. The velocity distribution at the exit of the Zeeman slower is obtained from a probe laser crossing the atom beam at an angle of 50 degrees. The fluorescence light is detected using a photomultiplier tube coupled with a boxcar analyzer. The Iron atom beam is produced with a commercial effusion cell working at around 1950 K. Our laser radiations are stabilized using standard saturated-absorption signals in both an Iron hollow cathode absorption cell and an Iodine cell. We will present our experimental setup, as well as the first evidences of cooled down Iron atoms at the exit of the Zeeman slower. [less ▲]

Detailed reference viewed: 25 (8 ULiège)
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See detailLaser Cooling of Iron Atoms
Bastin, Thierry ULiege; Huet, Nicolas ULiege; Krins, Stéphanie ULiege

Conference (2013, March 18)

We report on the first laser cooling of Iron atoms. Our laser cooling setup makes use of 2 UV laser radiation sent colinearly in a 0.8~m Zeeman slower. One laser is meant for optical pumping of the Iron ... [more ▼]

We report on the first laser cooling of Iron atoms. Our laser cooling setup makes use of 2 UV laser radiation sent colinearly in a 0.8~m Zeeman slower. One laser is meant for optical pumping of the Iron atoms from the ground state to the lowest energy metastable state. The second laser cools down the atoms using a quasi-perfect closed transition from the optical pumped metastable state. The velocity distribution at the exit of the Zeeman slower is obtained from a probe laser crossing the atom beam at an angle of 50 degrees. The fluorescence light is detected using a photomultiplier tube coupled with a boxcar analyzer. The Iron atom beam is produced with a commercial effusion cell working at around 1950 K. Our laser radiations are stabilized using standard saturated-absorption signals in both an Iron hollow cathode absorption cell and an Iodine cell. We will present our experimental setup, as well as the first evidences of cooled down Iron atoms at the exit of the Zeeman slower. [less ▲]

Detailed reference viewed: 67 (10 ULiège)
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See detailLaser Cooling of Iron Atoms
Huet, Nicolas ULiege; Krins, Stéphanie ULiege; Bastin, Thierry ULiege

Poster (2013, March 21)

We report on the first laser cooling of Iron atoms. Our laser cooling setup makes use of 2 UV laser radiations sent colinearly in a 0.8 m Zeeman slower. One laser is meant for optical pumping of the Iron ... [more ▼]

We report on the first laser cooling of Iron atoms. Our laser cooling setup makes use of 2 UV laser radiations sent colinearly in a 0.8 m Zeeman slower. One laser is meant for optical pumping of the Iron atoms from the ground state to the lowest energy metastable state. The second laser cools down the atoms using a quasi-perfect closed transition from the optically pumped metastable state. The velocity distribution at the exit of the Zeeman slower is obtained from a probe laser crossing the atomic beam at an angle of 50 degrees. The fluorescence light is detected using a photomultiplier tube coupled with a boxcar analyzer. The Iron atom beam is produced with a commercial effusion cell working at around 1600°C. Our laser radiations are stabilized using standard saturated-absorption signals in both an Iron hollow cathode absorption cell and an Iodine cell. [less ▲]

Detailed reference viewed: 95 (33 ULiège)
See detailLaser cooling of new atomic species - scheme of operation
Saint-Georges, P.; Krins, Stéphanie ULiege; Bastin, Thierry ULiege

Poster (2008)

Detailed reference viewed: 10 (1 ULiège)
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See detailLaser Induced Magnetization Reversal for Detection in Optical Interconnects
Al Azim, Z.; Xuanyao, Fong; Ostler, Thomas ULiege et al

in Electron Device Letters, IEEE (2014), 35(12), 1317-1319

Detailed reference viewed: 7 (0 ULiège)
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See detailLaser optics in space failure risk due to laser induced contamination
Kokkinos, Dimitrios ULiege; Schroeder, Helmut; Fleury-Frenette, Karl ULiege et al

in CEAS Space Journal (2017), 8

Detailed reference viewed: 37 (14 ULiège)
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See detailA laser profilometry technique for monitoring fluvial dike breaching in laboratory experiments
Dewals, Benjamin ULiege; Rifai, Ismail; Erpicum, Sébastien ULiege et al

Conference (2017, April)

A challenging aspect for experimental modelling of fluvial dike breaching is the continuous monitoring of the transient breach geometry. In dam breaching cases induced by flow overtopping over the whole ... [more ▼]

A challenging aspect for experimental modelling of fluvial dike breaching is the continuous monitoring of the transient breach geometry. In dam breaching cases induced by flow overtopping over the whole breach crest (plane erosion), a side view through a glass wall is sufficient to monitor the breach formation. This approach can be ex- tended for 3D dam breach tests (spatial erosion) ifthe glass wall is located along the breach centreline. In contrast using a side view does not apply for monitoring fluvial dike breaching, because the breach is not symmetric in this case. We present a non-intrusive, high resolution technique to record the breach development in experimental models of fluvial dikes by means of a laser profilometry (Rifai et al. 2016). Most methods used for monitoring dam and dike breaching involve the projection of a pattern (fringes, grid) on the dam or dike body and the analysis of its deformation on images recorded during the breaching (e.g., Pickett et al. 201 1, Frank and Hager 2014). A major limitation of these methods stems from reflection on the water surface, particularly in the vicinity of the breach where the free surface is irregular and rippled. This issue was addressed by Spinewine et al. (2004), who used a single laser sheet so that reflections on the water surface were strongly limited and did not hamper the accurate processing of each image. We have developed a similar laser profilometry technique tailored for laboratory experiments on fluvial dike breaching. The setup is simple and relatively low cost. It consists of a digital video camera (resolution of 1920 >< 1080 pixels at 60 frames per second) and a swiping red diode 30 mW laser that enables the projection of a laser sheet over the dike body. The 2D image coordinates of each defomied laser profile incident on the dike are transformed into 3D object coordinates using the Direct Linear Transformation (DLT) algorithm. All 3D object coordinates computed over a swiping cycle of the laser are merged to generate a cloud of points. The DLT-based image processing method uses control points and reference axes, so that no prior knowledge is needed on the position, orientation and intrinsic characteristics of the camera, nor on the laser position. Refraction of the light and laser rays across the water surface needs to be taken into account, because the dike is partially submerged during the experiments. An ad hoc correction is therefore applied using the Snell-Descartes law. For dtis purpose, planar approximations are used to describe the shape of the water surface. In the presen- tation, we will discuss the resulting uncertainty and will detail the validation of the developed method based on configurations of known geometry with various complexity. The presented laser profilometry technique allows for a rapid non-intrusive measurement of the dike geometry evolution. It is readily available for laboratory experiments and has proven its performance (Rifai et al. 2017). Further adjustments are needed for its application to cohesive dike material due to the reduced visibility resulting from the higher turbidity of water. [less ▲]

Detailed reference viewed: 24 (1 ULiège)
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See detailLaser steered ultrafast quantum dynamics of electrons in LiH.
Remacle, Françoise ULiege; Nest, M.; Levine, R. D.

in Physical Review Letters (2007), 99(18), 183902

The response of the electronic system of LiH to a few-cycle strong field is computed by a time-dependent multiconfiguration method using a large, adaptive, basis set. The intensity, pulse duration ... [more ▼]

The response of the electronic system of LiH to a few-cycle strong field is computed by a time-dependent multiconfiguration method using a large, adaptive, basis set. The intensity, pulse duration, polarization, and phase of carrier frequency can all be tuned to steer the motion of the electrons. It is shown possible to, e.g., direct the electrons to move along the Li-H bond or normal to it. By shifting the phase, the electrons can be driven toward the Li nucleus or away from it. When the pulse is polarized not along the bond the result is a rotation of the charge density. [less ▲]

Detailed reference viewed: 19 (2 ULiège)
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See detailLaser thermoreflectance for semiconductor thin films metrology
Gailly, Patrick ULiege; Hastanin, Juriy ULiege; Duterte, Charles et al

in Wehrspohn, R. B., Gombert, A (Ed.) Photonics for Solar Energy Systems IV (2012, June)

We present a thermoreflectance-based metrology concept applied to compound semiconductor thin films off-line characterization in the solar cells scribing process. The presented thermoreflectance setup has ... [more ▼]

We present a thermoreflectance-based metrology concept applied to compound semiconductor thin films off-line characterization in the solar cells scribing process. The presented thermoreflectance setup has been used to evaluate the thermal diffusivity of thin CdTe films and to measure eventual changes in the thermal properties of 5 μm CdTe films ablated by nano and picosecond laser pulses. The temperature response of the CdTe thin film to the nanosecond heating pulse has been numerically investigated using the finite-difference time-domain (FDTD) method. The computational and experimental results have been compared. [less ▲]

Detailed reference viewed: 58 (16 ULiège)
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See detailLaser Ultrasound for NDT: investigation of the generation beam shape
Languy, Fabian ULiege; Perrard, Aurélie; Vandenrijt, Jean-François ULiege et al

Poster (2016, July)

Usually laser ultrasonic systems use an infrared laser operating at 10 µm to generate the ultrasound in CFRP objects. However this system suffer from an important drawback: optical fiber cannot be used to ... [more ▼]

Usually laser ultrasonic systems use an infrared laser operating at 10 µm to generate the ultrasound in CFRP objects. However this system suffer from an important drawback: optical fiber cannot be used to transport the high energy beam from the laser output to the target which limits the flexibility of the system to investigated complex shaped objects. To overcome this issue, visible light can be used to generate ultrasound. In our case we use a fiber-coupled laser operating at 532 nm. The output end of the optical fiber is placed on an industrial robot arm. The investigated object remains stationary while the optical fiber mounted on the robot arm scan the object. This system offers large flexibility but laser generation at 532 nm is known to be less efficient than CO 2 system emitting at 10 µm. Increasing the visible pulse power is one of the options but optics and CRFF object will be damaged before the same echo level as CO2 generation can be obtained. An alternative solution consists in the investigation of the generation beam size and shape. We recently developed an optical design composed of an axicon lens able to generate annular beam. The diameter of the beam can be adapted. If the axicon lens is removed the optical system provides a disk whose diameter can also be adapted onto the investigated object. Ray-traycing simulations performed with ASAP and experimental beam profile investigated with a beam profiler show good agreement between theoretical and experimental optical design. An experimental comparison between ring and disk shapes will be presented. The comparisons take into account the beam diameter and the beam intensity but also the effect of the angle of incidence will be presented. [less ▲]

Detailed reference viewed: 69 (6 ULiège)
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See detailLaser-assisted dielectronic recombination in C4+ ions
Bachau, H.; Gayet, R.; Lambropoulos, P. et al

in Journal of Physics : B Atomic Molecular & Optical Physics (1998), 31(14), 3263-3280

We study the effect of laser-driven transitions between autoionizing resonances on the dielectronic recombination rates observed after the formation of such resonances in electron-ion collisions. The ... [more ▼]

We study the effect of laser-driven transitions between autoionizing resonances on the dielectronic recombination rates observed after the formation of such resonances in electron-ion collisions. The autoionizing states of S-1(e) and P-1(0) symmetry belonging to the 2l2l' and 2l3l' configurations of C4+ are considered. The resonance parameters are calculated in the Feshbach formalism and compared with other accurate calculations, and transition dipole moments between the autoionizing states are obtained. The rates of dielectronic recombination and autoionization under the influence of the laser field are calculated using the density matrix approach for realistic parameters. A simple formulation of the problem is also proposed in the resolvent operator technique. The feasibility of an experiment is discussed. [less ▲]

Detailed reference viewed: 12 (1 ULiège)
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See detailLaser-induced breakdown spectroscopy for analysis of soil elements
Lin, Zhaoxiang; Li, Jie ULiege; Liu, Linmei et al

in High Power Laser and Particle Beams (2009), 21(6), 817820

A laser—induced breakdown spectroscopy(LIBS)set—up has been established,and a series of experiments have been carried out with soil samples.The calibration curves of the lines intensities versus the mass ... [more ▼]

A laser—induced breakdown spectroscopy(LIBS)set—up has been established,and a series of experiments have been carried out with soil samples.The calibration curves of the lines intensities versus the mass fraction of the elements were acquired by the experiment.Eighteen elements including Mg,Ca and Na were found in the sample of the soil around the South—Central University for Nationalities by qualitative analysis.Only three elements,Fe,Mg and Ca,were found in the rock at Zhuyufeng peak.These results indicate that the physical composition of soil sample impact on the precision of LIBS. [less ▲]

Detailed reference viewed: 33 (3 ULiège)
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See detailLaser-induced choroidal neovascularization model to study age-related macular degeneration in mice.
LAMBERT, Vincent ULiege; Lecomte, Julie ULiege; Hansen, Sylvain ULiege et al

in Nature Protocols (2013), 8(11), 2197-2211

The mouse model of laser-induced choroidal neovascularization (CNV) has been used extensively in studies of the exudative form of age-related macular degeneration (AMD). This experimental in vivo model ... [more ▼]

The mouse model of laser-induced choroidal neovascularization (CNV) has been used extensively in studies of the exudative form of age-related macular degeneration (AMD). This experimental in vivo model relies on laser injury to perforate Bruch's membrane, resulting in subretinal blood vessel recruitment from the choroid. By recapitulating the main features of the exudative form of human AMD, this assay has served as the backbone for testing antiangiogenic therapies. This standardized protocol can be applied to transgenic mice and can include treatments with drugs, recombinant proteins, antibodies, adenoviruses and pre-microRNAs to aid in the search for new molecular regulators and the identification of novel targets for innovative treatments. This robust assay requires 7-14 d to complete, depending on the treatment applied and whether immunostaining is performed. This protocol includes details of how to induce CNV, including laser induction, lesion excision, processing and different approaches to quantify neoformed vasculature. [less ▲]

Detailed reference viewed: 245 (44 ULiège)
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See detailLaser-induced contamination and its impact on laser damage threshold
Schröder, H; Wagner, P; Kokkinos, Dimitrios ULiege et al

in Laser-induced contamination and its impact on laser damage threshold (2013, November 14)

Detailed reference viewed: 38 (17 ULiège)