Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 168 for “"laser pulse"”.
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Damages in Transparent Materials by Ultrashort Laser Pulse
Ultrashort lasers that generate laser pulses down to picosecond and femtosecond range have advanced over the past decade from delicate lab systems to robust industry machines. The availability of stable ultrashort laser systems opens up a wide range of exciting applications from transparent …
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Studies of Spectral Modification in Intense Laser Pulse-Plasma Interactions
Laser pulses propagating through plasma undergo spectral broadening through local energy exchange with driven plasma waves. During propagation, a high power laser pulse drives large amplitude plasma waves, depleting the pulse energy. At the same time, the large amplitude plasma wave provides a …
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Ultrashort laser pulse-matter interaction: Fundamentals and early stage plasma dynamics
… years, the detailed mechanisms of ultrashort laser pulse (USLP)-matter interaction are still not fully understood and further fundamental investigation is required. This study seeks to provide an improved understanding of the USLP-material interaction by both theoretical and experimental …
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Proton acceleration experiment by high intensity laser pulse interaction with solid density target at the Texas Petawatt Laser Facility
In recent, high intensity laser pulse interaction with solid density matter has been studied in several laboratory and facilities. Multi-MeV proton and ion beams from plasma produced by this interaction is one important application research area of HEDP. In this thesis, the basic theory of hot …
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Intra-pulse dynamics of laser-driven ion acceleration in ultra-thin foils
… driven by the interaction of short, intense laser pulses with ultra-thin, solid targets in which relativistic transparency is induced. In particular, it explores the multiple laser-ion acceleration mechanisms that take place over the duration of the laser pulse. Investigating these …
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Optische Kontrolle der Lasertätigkeit im Röntgenbereich
X-ray free-electron lasers have revolutionized x-ray science by achieving unprecedented intensities exceeding 10^18 W/cm^2. However, they lack temporal coherence and controllability of their pulses' temporal and spatial properties, which is essential for many applications. We investigate the …
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Approximate solution of melt depth inside titanium during laser materials processing
The use of lasers has increased in areas of science, engineering and medicine. Their advantages over the traditional methods of thermal application are their ability to localize thermal treatments, ability to deliver high power density and to complete thermal processes in extremely short time …
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Demonstration of filament-guided electrical discharges from a high average power 1 kHz picosecond laser
… propagation of ultrashort, high energy laser pulses is of interest for applications including remote sensing, directed energy, and the guiding of lightning. In this thesis, the filamentation of high energy picosecond laser pulses at repetition rates up to 1 kHz is demonstrated and the …
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All-solid-state femtosecond medical lasers and nonlinear laser-tissue interactions
Diode pumped all-solid-state ultrafast lasers are promising for mini-invasive refractive surgery and keratoplasty. A funda mental systematical study concerning ultrafast laser tissue interactions is crucial before applying the state of the art laser technology to ophthalmic applications. Porcine …
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Dynamics of vibrational energy flow, quantum computing and laser assisted fusion
… for one and two qubits gates, using conventional pulse shaper techniques. However, optimal control theory increases the fidelity for a two qubits gate up to 0.9999. In addition, I simulated the dynamics of two bare nuclei (deuterium-tritium) interacting with a shaped femtosecond laser pulse in one …
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Pulsed laser ablation deposition and optical characterization of hexagonal-wurtzite silicon
… a simple deposition system demonstrated that laser ablation of the standard cubic-diamond silicon produces droplets containing hexagonal-wurtzite crystallites. In order to study the process parameters and to deposit larger hexagonal crystals, a new pulsed laser ablation system with variable …
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Experimental characterization of Cr4+:YAG passively Q-switched Cr:Nd:GSGG lasers and comparison with a simple rate equation model
… a study on the comparison and anlysis of a laser rate equation model and the laboratory performance of passively Q-switched microlasers. The laser rate equation model describes the development of a top hat gain distribution taking into account the excited state absorption of the passive …
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Local absorption enhancement of light in tailored disordered amorphous silicon thin-films
… of the fabricated nanotextures via short laser pulse excitation reveals localized modes that significantly increase the overall absorption.
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Intense laser matter interactions for explosives detection and tunable spectral blueshift
… shifts induced in metal surfaces by ultrafast laser pulses at intensities ranging from 1013 to 1014 W/cm2. These ~100 femtosecond (fs) pulses facilitate non-resonant vaporization of explosives, enabling non-contact sampling and detection. When coupled with electrospray post-ionization, fs laser …
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Radiation reaction in strong fields from an alternative perspective
… on a particle colliding with an ultra-intense laser pulse we show that the regime where there is a significant deviation of these two approaches can never be reached with existing or proposed laser facilities. The methods used to explore single particle interaction with an intense laser pulse …
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Timing Diagnostics and Coherent Harmonics from a test-FEL
The test free-electron laser (test-FEL) at MAX-lab in Lund demonstrated for the first time circularly polarized coherent femtosecond pulses at 66 nm wavelength. A 375 MeV electron bunch was seeded by a femtosecond laser at 263 nm and coherent harmonics were extracted in an APPLE-II type elliptical …
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Stabilization of autoionizing states
… in Barium was examined for the case when a laser field was used to induce stimulated emission of the excited core electron. Stabilization is referred to all the atoms that form a singly excited neutral state after being in a doubly excited autoionizing state. Relative to pure fluorescence, …
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Time and temperature dependence of stimulated brillouin scattering in fused silica
… is achieved during the finite length of the laser pulse. Theoretically, this problem is most acute in solids, where acoustic phonon lifetimes can be of the same order of magnitude as the laser pulse length. This situation was investigated experimentally and it was found that (a) the rise of …
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Modal analysis of laser vibrated structures
This thesis describes the laser irradiation of metallic structures to excite mechanical vibrations within those structures. As found by other authors, single high-power laser pulses ablate the irradiated surface material and may impulsively excite structural vibration; however, the use of laser …
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An Optically-Pumped Frequency Stable Tunable Maser and Infrared-Microwave Double-Resonance Experiments in Ammonia
… from ('14)NH(,3) optically pumped by a CO(,2) laser. The emission is tunable over the saturated homogeneous linewidth of the ground state sQ(5,4) inversion transition at 22.653 GHz. The circulating power density of the optically pumped emission is 0.54 watts/cm('2) at NH(,3) pressure of 0.91 …
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