Dissertations / Theses on the topic 'Laser excitation'
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Mazzotta, Z. "POSITRONIUM LASER EXCITATION IN THE AEGIS EXPERIMENT." Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/468556.
Full textXu, Bingwei. "Control of multiphoton molecular excitation with shaped femtosecond laser pulses." Diss., Connect to online resource - MSU authorized users, 2008.
Find full textLeclerc-Perron, Jérôme. "Laser à miroirs de Bragg à excitation impulsionnelle." Master's thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26485.
Full textThe emergence of erbium doped glasses has allowed the development of many technologies. However, applications such as LIDAR, infrared spectroscopy and infrared sources for optical parametric oscillators all benefit from having a wide gain bandwidth farther in the infrared than what erbium doped glasses allow. Thulium has shown to be a good candidate for such applications due to its wide gain bandwidth ranging from 1.7 μm to 2.1 μm. Inspired by the success in laser pulse generation from erbium doped media, many researchers decided to apply the knowledge acquired from erbium doped laser sources to thulium doped laser sources. We chose to use a linear distributed Bragg reflector cavity, which allows us to implement a monolithic laser of a very small size. Depending on the pumping scheme, it is possible to operate this laser in a CW regime as well as in a pulsed regime. This document details the implementation of a thulium doped fiber laser in a linear cavity with distributed Bragg reflectors. We first develop the theoretical model used for the simulation of our laser’s dynamics. This model allows us to implement numerical simulations able to treat pulsed pumping, dispersive effects induced by the fiber Bragg grating and intrinsic nonlinear effects. We then characterize the erbium-ytterbium doped phosphate fiber amplifier used to generate pump pulses, along with the other components of the thulium doped fiber laser cavity. The numerical model is then validated by comparing numerical simulations to experimental results obtained from our thulium doped laser.
Comet, Maxime. "Excitation du 201 Hg dans les plasmas produits par laser." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0458/document.
Full textThe use of high power lasers allows the study of the properties of matter in extremeconditions of temperature and density. Indeed, the interaction of a power laser and atarget creates a plasma in which the temperature is high enough to reach important degrees of ionization. These conditions can allow the excitation of the nucleus. Anucleus of interest to study the processes of nuclear excitation is the 201 Hg. Thiswork aims to design an experiment where the 201 Hg excitation will be observed in aplasma produced by a high power laser. The first part of this manuscript presents the calculation of the expected nuclear excitation rates in the plasma. For about ten years, nuclear excitation rates have been calculated using the average atom model. To validate this model a code named ADAM (french acronym for Beyond The Average Atom Model) was developed to calculate the nuclear excitation rates under the DCA (Detailed Configuration Accounting) hypothesis. ADAM allows us to deduce the thermo dynamical domain where the nuclear excitation rates determined with the average atom model are relevant. The second part of this manuscript presents the coupling of the excitation rate calculation with a hydrodynamic code to calculate the number of excited nuclei produced in one laser shot for different laser intensity. Finally, in the last part, first experimental approaches which will be used to design an experiment on a laser installation are presented. These approaches are based on the detection and determination of the amount of multicharged ions obtained far from the target (~80 cm). For this purpose, an electrostatic analyzer was used
Papastathopoulos, Evangelos. "Adaptive control of electronic excitation utilizing ultrafast laser pulses." Doctoral thesis, [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975015184.
Full textTojira, Opas. "Single-molecule fluorescence spectroscopy : Implementation of alternating-laser excitation." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531514.
Full textHan, T. P. J. "Solid state spectroscopy: laser selective excitation studies of neodymium." Thesis, University of Canterbury. Physics, 1988. http://hdl.handle.net/10092/7972.
Full textDeller, Adam. "Positron accumulation and laser excitation of the positronium atom." Thesis, Swansea University, 2013. https://cronfa.swan.ac.uk/Record/cronfa42868.
Full textLenain, Bruno. "Microspectrofluorimétrie à excitation laser et détection multicanale : instrumentation - possibilités - applications." Lille 1, 1989. http://www.theses.fr/1989LIL10047.
Full textSille, E. C. "A study of the zinc segmented plasma excitation and recombination laser." Thesis, University of Essex, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371870.
Full textReeves, Roger J. "Laser selective excitation of praseodymium ions in hydrogenated fluorite crystals." Thesis, University of Canterbury. Physics, 1987. http://hdl.handle.net/10092/8218.
Full textRebello, Jagdish Hilary Diago. "Synthesis of Diamond by Selective Laser Excitation of Gaseous Precursors /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487928649986997.
Full textModoran, Georgia C. "Intense field electron excitation in transparent materials." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1133273960.
Full textDurrani, Sardar Mohammad Ayub. "Optimization of RF discharges for excitation of CO2 lasers." Thesis, Heriot-Watt University, 1988. http://hdl.handle.net/10399/986.
Full textWokosin, David Lee. "Characterisation of excitation mode and dose for laser scanning fluorescence microscopy." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415298.
Full textVolfbeyn, Pavel S. "Experimental studies of laser guiding and wake excitation in plasma channels." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50010.
Full textVilla, F. "LASER SYSTEM FOR POSITRONIUM EXCITATION TO RYDBERG LEVELS FOR AEGIS EXPERIMENT." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/168730.
Full textBooth, James L. "On the ortho - para enhancement of molecular iodine by selective laser excitation." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24484.
Full textScience, Faculty of
Physics and Astronomy, Department of
Graduate
Gavérina, Ludovic. "Caractérisation thermique de milieux hétérogènes par excitation laser mobile et thermographie infrarouge." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0012/document.
Full textNowadays, composite materials are widely used in the aeronautic and aerospace industries because of their high mechanical resistance. However, they have a large heterogeneity due to the fiber and matrix they are made of. In this way, for many years, the TIC team «Thermal Imaging Fields and Characterization » from TREFLE department of I2M laboratory develops methods to measure thermal in-plane properties of heterogeneous materials such as inverses (integral transforms, double singular value decomposition…) or experimental (Flash, laser diode…) methods. The recent progress made in optical control, lasers and infrared (IR) cameras enables the development of a new scanning system (based on galvanometer-mirror) which allows the easy control of a laser hot spot spatial and temporal displacements over a plane surface. The low cost of laser diodes and optical control (galvanometric mirror) systems allows to develop a laser scanning system fixed on a test bench. We can revisit the different types of thermal excitation and realize infinite spatio-temporal combinations of thermal excitations by laser method. This is one of this thesis aims. New inverse methods based on the thermal response to an instantaneous point source heating, and temperature fields separability, have been proposed. These methods allow to estimate the thermal diffusivity tensor along the main axes of anisotropy, but also out of those axes, where it is possible to estimate the anisotropy axes orientation when the heat transfer takes place out of the image axes. These methods have produced interesting results in view of their simplicity. Moreover, they made it possible to obtain in-plane thermal diffusivities maps because, compared to the other methods, they allow to obtain, locally, thermal diffusivity tensor estimations by getting a surface heat flux map using the laser optical scanner
Evans, D. R. "Multiple glow discharges for the excitation of a high power CO2 laser." Thesis, Loughborough University, 1987. https://dspace.lboro.ac.uk/2134/31977.
Full textCockroft, Nigel J. "Solid state spectroscopy : laser selective excitation of erbium ions in crystalline solids." Thesis, University of Canterbury. Physics, 1987. http://hdl.handle.net/10092/8056.
Full textMujaji, Marjorie. "Solid state spectroscopy : laser selective excitation of holmium ions in crystalline solids." Thesis, University of Canterbury. Physics, 1992. http://hdl.handle.net/10092/8145.
Full textRämer, Anika [Verfasser]. "Excitation and Relaxation Dynamics in Laser-Excited Semiconductors and Dielectrics / Anika Rämer." München : Verlag Dr. Hut, 2017. http://d-nb.info/1139538071/34.
Full textDe, Clercq Ludwig Erasmus. "Numerical modelling of the excitation of polyatomic molecules by femtosecond laser beams." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6522.
Full textENGLISH ABSTRACT: The selective excitation of an arbitrary vibrational level of a polyatomic molecule, without passage through an intermediary electronic excited state is demonstrated. This was achieved by simulating the interaction of a shaped, femtosecond pulse with one vibrational mode of the molecule. The carrier frequency of the pulse is chosen near resonant to the ground-to- rst-excited vibrational transition of the mode, and the pulse shape is optimized via closed-loop feedback. The simulation concentrates on the rst few vibrationally excited states since the density of states is still low, thus ensuring that the inter-vibrational decoherence time is relatively long compared to the pulse length. While various molecules were investigated this study focuses onUF6 for which detailed spectroscopic data for the v3 vibrational mode is available in literature. A multilevel model was developed and can be adapted for any number of levels. The model reported here was limited to a vibrational quantum number of four. The spectroscopic data included anharmonic splitting as well as forbidden transitions. The effect of rotational levels was not included. A density matrix approach was followed because this will allow for the introduction of dephasing of the coherent excitation via thermalizing collisions with the reservoir, as well as inter-vibrational relaxation. The time evolution of the density matrix is given by the Von Neumann equations.
AFRIKAANSE OPSOMMING: Die selektiewe opwekking van 'n arbitrêre vibrasionele vlak van 'n poliatomies molekule sonder oorgang na 'n intermediëre elektroniese opgewekte toetstand word gedemonstreer. Dit was bereik deur die interaksie te simuleer van 'n gevormde, femtosekonde pulse met een vibrasionele mode van 'n molekule. Die draer frekwensie van die pulse is so gekies dat dit naby resonansie van die grond-tot-eerste-opgewekte vibrasionele oorgang van die mode is, die puls vorm word geoptimeer deur 'n geslote-lus terugvoer. Die simulasie konsentreer op die eerste paar vibrasionele opgewekte toestande, omdat die digtheid van toestande nog steeds laag is, dus verseker dit dat inter-vibrasionele de-koherensie tyd relatief lank is in vergelyking met die puls se lengte. Verskillende molekules was ondersoek vir die studie. Die fokus is op UF6 waarvoor gedetaileerde spektroskopiese data vir die v3 vibrasionele beskikbaar is in die literatuur. 'n Multivlak model was ontwikkel en kan aangepas word vir enige aantal van vlakke. Die model wat hier aangemeld is, is beperk tot die vibrasionele kwantum getal van vier. Die spektroskopiese data het anharmonies splitting so wel as nie toegelaatbare oorgange bevat. Die effek van rotasionele vlakke was nie in berekening geneem nie. 'n Digtheids matriks benadering was gevolg, omdat dit toelaat vir die dekoherensie. Die tyd evolusie van die digtheids matriks word gegee deur die Von Neumann vergelykings.
Bigongiari, Alessandra. "High Intensity Laser-Plasma Grating Interaction : surface wave excitation and particle acceleration." Palaiseau, Ecole polytechnique, 2012. http://pastel.archives-ouvertes.fr/docs/00/75/83/55/PDF/alebigo_TESI_rapporteurs.pdf.
Full textSurface waves in solids were first observed by Wood in 1902 as an anomaly in the diffraction of a continuous light source from a metal grating: the diffracted spectrum presented dark lines corresponding to certain wavelengths, which were later explained (Fano, 1941) in terms of the excitation of a surface wave sustained by the grating. Similarly to the metal grating case, a surface plasma wave (SPW) can be resonantly excited by a laser pulse at the surface of a laser-produced over-dense plasma, if the correct matching conditions are provided. SPWs propagate along the plasma-vacuum interface and are characterized by a localized, high frequency, resonant electric field. In the present work we describe numerically the dynamics of the plasma and the field distribution associated to SPW excitation, using two-dimensional particle-in-cell (PIC) simulations, where the plasma surface is initially pre-formed so that the SPW excitation conditions are fulfilled. We examine the surface wave excitation for a large range of laser intensities (Iλ2 =10^15-10^20 μm^2/Wcm^2) in order to study the transition from the non-relativistic to the relativistic regime. The simulations in which the wave is resonantly excited are compared to cases in which the resonant conditions are not provided and the coupling of the laser with the target is analyzed. We have considered the following aspects of the laser-plasma interaction, for different laser and target parameters: i) the laser absorption and the electric field at the surface ii) the generation of a quasi-static magnetic field iii) the electron heating and iiii) the ion acceleration. The possibility to excite a surface plasma wave on a structured target for a large range of laser energies has been demonstrated. In the cases where the surface wave is excited the electric field component normal to the target is amplified at the surface by a factor ranging from 3. 2 to 7. 2 with respect to the laser field. The absorption is also increased,for example it raises from 27% when the SPW is not excited up to 73% for Iλ^2=10^9 μm^2/Wcm^2. We have defined the optimal conditions for efficient coupling which increase laser absorption, that correspond to the relativistic laser intensities (Iλ^2>10^19 μm^2/Wcm^2). In this regime the main absorption mechanism is vacuum heating, associated to particles oscillating in the field perpendicular to the target, which is enhanced by the stronger, localized field of the SPW. The generation of a quasi-static magnetic field has been studied analytically and compared to the result of PIC simulations. The different field structure in presence of a SPW and for a flat target suggests that the enhanced field strength has caused partial confinement of particles at the target surface when SPW is present. The effects of the surface wave are more pronounced in thin laminar targets where electrons recirculate into the target interacting several times with the wave. Efficient electron heating increases the energy of the ions which are accelerated at both the irradiated and not irradiated target surface by the hot electrons space charge field. For the thinnest target (3. 5 μm) the ion cut-off energy is about 14 Mev, approximately twice the value obtained when the SPW is not excited
Wang, Yuchen, Xiushan Zhu, Jie Zong, Kort Wiersma, Arturo Chavez-Pirson, Robert A. Norwood, and N. Peyghambarian. "SESAM Q-switched fiber laser at 1.2 mu m." IEEE, 2016. http://hdl.handle.net/10150/622787.
Full textRosano, William Joseph. "Chemiluminescence and laser induced fluorescence of the group IVA and IB elements with halogen molecules /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487263399026961.
Full textRaymond, Xavier. "Développement d'une source pulsée d'électrons extraits d'un plasma produit par laser." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0142/document.
Full textThis Ph.D thesis describes the development of an intense and brief electron beam and forms part of the research on the nuclear properties of matter in hot and dense plasmas. In order to obtain such a beam, a new source has been created, the principle is based on the extraction of electrons from a plasma produced by an intense laser pulse. The characterization of the laser-produced plasma during its expansion is the subject of a first experimental part of this thesis. Then, an electrical potential of the order of a few kV applied to the plasma during its expansion shows that the extraction of the electrons is a dynamic process. These experimental observations are validated by numerical studies using Particle-In-Cell simulation code "XOOPIC". Finally, the surface and energy distributions of the electrons extracted from the plasma are determined experimentally and numerically throughout the plasma expansion, which is the final part of this thesis. For this, a Faraday Cup type detector is used. An analysis of the emission intensity of the electron current with a numerical model shows the presence of a pre-plasma providing an additional extracting electric field
Goodridge, Damian Mark. "The green and red systems of the FeH radical." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339345.
Full textCooper, Ben. "Laser excitation of positronium produced in various materials at a range of temperatures." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10044312/.
Full textKhelkhal, Mohammed. "Étude et réalisation d'un laser à CO2 pris en main à excitation radiofréquence." Lille 1, 1992. http://www.theses.fr/1992LIL10094.
Full textGRUSS, CHRISTIAN. "Caméra photothermique : étude théorique et réalisation d'une caméra infrarouge active avec excitation laser." Poitiers, 1993. http://www.theses.fr/1993POIT2352.
Full textShchemelyov, Sergey. "Sum-frequency generation and multiphoton ionization in xenon under excitation by conical laser beams /." Online version, 2006. http://dspace.utlib.ee/dspace/bitstream/10062/1001/5/shchemelyovsergey.pdf.
Full text陳志遠 and Chee-yuen George Chan. "Investigation of matrix effects on excitation conditions of dry inductively coupled plasma using laser ablation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B42128687.
Full textChan, Chee-yuen George. "Investigation of matrix effects on excitation conditions of dry inductively coupled plasma using laser ablation." Click to view the E-thesis via HKUTO, 2000. http://sunzi.lib.hku.hk/hkuto/record/B42128687.
Full textDurand-Noyer, Agnès. "Effet Stark de la molécule ICl : états pendulaires." Toulouse 3, 1995. http://www.theses.fr/1995TOU30294.
Full textSang, Robert Thomas, and n/a. "Superelastic Electron Scattering from Laser Excited States of Sodium." Griffith University. School of Science, 1995. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050921.120911.
Full textBeaulieu, Nathan. "Propriétés électroniques et magnétiques sous excitation laser femtoseconde, du Gd monocristallin aux alliages ferrimagnétiques." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00953656.
Full textSenanayake, Pubudu Seewali. "Two-Colour Excitation of Impurity Trapped Excitons in Wide Bandgap Insulators." Thesis, University of Canterbury. Department of Physics and Astronomy, 2013. http://hdl.handle.net/10092/8710.
Full textLiu, Yuyan. "Far infrared laser magnetic resonance spectroscopy of free radicals." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364594.
Full textSaad, Rawad. "Etudes physico-chimiques des plasmas induits par laser pour l'analyse quantitative des matériaux dans les systèmes nucléaires." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0172/document.
Full textLaser Induced Breakdown Spectroscopy (LIBS) is a multi-elemental analysistechnique very well suited for analysis in hostile environments particularly in thenuclear industry. Quantitative measurements are frequently performed on liquid orsolid samples but in some cases, atypical signal behaviors were observed in theLIBS experiment. To avoid or minimize any impact on measurement accuracy, it isnecessary to improve the understanding of these phenomena. In the framework of athree-year PhD thesis, the objective was to study the chemical reactions occurringwithin laser-generated plasma in a LIBS analysis. Experiments on a model material (pure aluminum sample) highlighted thedynamics of molecular recombination according to different ambient gas. Thetemporal evolution of Al I atomic emission lines and molecular bands of AlO and AlNwere studied. A collisional excitation effect was identified for a peculiar electronicenergy level of aluminum in the case of a nitrogen atmosphere. This effectdisappeared in air. The aluminum plasma was also imaged during its expansionunder the different atmospheres in order to localize the areas in which the molecularrecombination process takes place. Spectacular particle projections have beenhighlighted
Little, Helen. "Optical micromanipulation using ultrashort pulsed laser sources." Thesis, St Andrews, 2007. http://hdl.handle.net/10023/338.
Full textMartinelli, Gilbert. "Réponse spatio-temporelle d'un résonateur de Fabry-Perot en régime non linéaire sous excitation picoseconde." Limoges, 1990. http://www.theses.fr/1990LIMO0088.
Full textAlessandra, Bigongiari. "Interaction laser-réseau plasma à haute intensité: excitation d'une onde de surface et accélération de particules." Phd thesis, Ecole Polytechnique X, 2012. http://pastel.archives-ouvertes.fr/pastel-00758355.
Full textZhao, Chunfeng. "High-resolution laser excitation spectroscopy of metal-containing free radicals using a supersonic molecular beam spectrometer." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq22256.pdf.
Full textStachel, Sebastian [Verfasser], and Sergey [Akademischer Betreuer] Ganichev. "Magnetic field induced photocurrents in semiconductor nanostructures under THz laser excitation / Sebastian Stachel. Betreuer: Sergey Ganichev." Regensburg : Universitätsbibliothek Regensburg, 2013. http://d-nb.info/1044159901/34.
Full textTurnidge, Martin Laurence. "Vibrational energy transfer at low temperatures and the use of infrared laser excitation for trace detection." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337427.
Full textSchauman, Julia, and Linnea Bendrot. "Two-Photon Excitation of a GaAs Quantum Dot by Electro-Optically Modulating a Continuous Wave Laser." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-275736.
Full textEn nyckelkomponent i utvecklingen av kvantkommunikation är integrationen av enskilda fotoner och kvantminnen, något som skulle möjliggöra utveckligen av kvantrepeterare. Som del av ett större forskningsprojekt var målet med detta kandidatarbete att producera enskilda fotoner som framgångsrikt skulle kunna lagras i ett rubidium baserat kvantminne. Vi presenterar i denna rapport hur en kvantprick av galliumarsenid framgångsrikt kan exciteras av en laser som pulsats genom elektrooptisk modulering av en kontinuerlig laser. När effekten hos excitations lasern är tillräckligt hög för π-puls-excitation av kvantpricken erhålls ett g^(2)(0)-värde på 0.048976±0.000831. Det visar på möjligheten att uppnå högkvalitativa enskilda fotoner från en kvantprick som exciteras av en elektrooptiskt modulerad kontinuerlig laser.
Li, Ran. "Molecular Characterization of Human Tissue Samples by Raman Spectroscopy with Different Laser Modes and Excitation Wavelengths." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1365419543.
Full textAjinou, Abdelkader. "Réponses photo-thermique et photo-élastique de nanostructures, à une excitation par une impulsion laser femtoseconde." Paris 13, 2001. http://www.theses.fr/2001PA132023.
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