Thesis (Ph. D.)--University of Oregon, 1999. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 197-201). Also available for download via the World Wide Web; free to University of Oregon users. Address: http://wwwlib.umi.com/cr/uoregon/fullcit?p9948024.

Thesis (PH. D.)--Michigan State University. Chemistry, 2008. / Title from PDF t.p. (viewed on Sept. 8, 2009) Includes bibliographical references (p. 134-148). Also issued in print.

Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2006. / Trebino, Rick, Committee Chair ; First, Phillip, Committee Member ; Ralph, Stephen, Committee Member ; Kennedy, Brian, Committee Member ; Buck, John, Committee Member.

Thesis (M.Phil.) - University of St Andrews, June 2009.

Thesis (M.S.)--Brigham Young University. Dept. of Physics and Astronomy, 2006. / Includes bibliographical references (p. 61-64).

In this thesis we ran a series of 2D simulations of femtosecond laser pulses filamenting in air using the FDTD method, a saturable Lorentz oscillator model of air [1], and two separate models of plasma: a Drude model where the plasma density is static in space, and a particle-in-cell model where plasma is free to migrate throughout the simulation space. By comparing matched pairs of simulations, which varied in pulse size, duration, and intensity, we can gauge the impact plasma dynamics has upon the evolution of a filamenting laser pulse. From these tests we determine that, while there are some visible differences between dynamic and static plasmas, plasma dynamics do not significantly alter the evolution of the pulse.

No description available.

The emergence of mode-locked oscillators providing pulses with durations as short as a few electric-field cycles in the near infra-red has paved the way toward electric-field sensitive physics experiments. In addition, the control of the relative phase between the carrier and the pulse envelope, developed in the early 2000’s and rewarded by a Nobel price in 2005, now provides unprecedented control over the pulse behaviour. The amplification of such pulses to the millijoule level has been an on-going task in a few world-class laboratories and has triggered the dawn of attoscience, the science of events happening on an attosecond timescale. This work describes the theoretical aspects, modeling and experimental implementation of HERACLES, the Laser Plasma Laboratory optical parametric chirped pulse amplifier (OPCPA) designed to deliver amplified carrier-envelope phase stabilized 8-fs pulses with energy beyond 1 mJ at repetition rates up to 10 kHz at 800 nm central wavelength. The design of the hybrid fiber/solid-state amplifier line delivering 85-ps pulses with energy up to 10 mJ at repetition rates in the multi-kHz regime tailored for pumping the optical parametric amplifier stages is presented. The novel stretcher/compressor design of HERACLES, suitable for handling optical pulses with spectra exceeding 300 nm of bandwidth with unprecedented flexibility, is fully modeled and also presented in the frame of this thesis. Finally, a 3D model of the multistage non-collinear optical parametric amplifier is also reported. The current and foreseen overall performances of HERACLES are presented. This facility is designed to enable attosecond physics experiments, high-harmonic generation and physics of plasma studies.

A numerical model of the temperature field during pulsed laser cutting of thin sheets (approximately 2.5 x l0⁻⁵ m) was developed. Cutting was simulated through removal of nodes from a finite difference scheme based on sensible heating to the phase change temperature and a single value of latent heat (melting or vaporization). The pulsed laser model predicts a heat-affected zone of less than 0.02 mm for pulsed laser cutting. For comparable cutting with a continuous power laser, a heat-affected zone between 0.05 and 0.10 mm is predicted. Thermal stress levels were predicted to be an order of magnitude lower for pulsed laser cutting than for continuous power cutting. The stress levels predicted by the model also increased with cut speed. Experimentally, pulsed laser cutting yielded better cut quality, based on less cracking, than continuous power cutting. In addition, the cut quality deteriorated as the cutting speed was increased for the continuous power laser. Presently, application of pulsed laser cutting is limited by its low cutting speed, which is restricted by the energy density of the laser. The model predicts that increasing energy density will decrease the size of the heat-affected zone and increase the maximum cutting speed. Therefore, pulsed laser cutting at high speeds should be attainable without deterioration in cut quality. / Master of Science

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: In this work we investigate a new method to measure the electric field of ultrafast laser pulses by extending a known measurement technique, ptychography, in the spatial domain to the time domain which we call time domain ptychography. The technique requires the measurement of intensity spectra at different time delays of an unknown temporal object and a known probe pulse. We show for the first time by measurement and calculation that this technique can be applied with excellent results to recover both the amplitude and phase of a temporal object. This technique has several advantages, such as fast convergence, the resolution is limited by the usable measured spectral bandwidth and the recovered phase has no sign ambiguity. We then extend the technique to pulse characterization where the probe is derived form the temporal object by filtering meaning the probe pulse is also unknown, but the spectrum of the probe pulse must be the same as the spectrum of the temporal object before filtering. We modify the reconstruction algorithm, now called ptychographic iterative reconstruction algorithm for time domain pulses (PIRANA), in order to also reconstruct the probe and we show for the first time that temporal objects, a.k.a laser pulses, can be reconstructed with this new modality. / AFRIKAANSE OPSOMMING: In hierdie werk het ons ’n nuwe metode ondersoek om die elektriese veld van ’n ultravinnige laser puls te meet deur ’n bekende meettegniek wat gebruik word in die ruimtelike gebied, tigografie, aan te pas vir gebruik in die tyd gebied genaamd tyd gebied tigografie. Die tegniek vereis die meting van ’n reeks intensiteit spektra by verskillende tyd intervalle van ’n onbekende ‘tyd voorwerp’ en ’n bekende monster puls. Ons wys vir die eerste keer deur meting en numeriese berekening dat hierdie tegniek toegepas kan word met uitstekende resultate, om die amplitude en fase van ’n ‘tyd voorwerp’ te meet. Hierdie tegniek het verskeie voordele, die iteratiewe proses is vinnig, die resolusie van die tegniek word bepaal deur die spektrale bandwydte gemeet en die fase van die ‘tyd voorwerp’ word met die korrekte teken gerekonstrueer. Ons het hierdie tegniek uitgebrei na puls karakterisering waar die monster pulse afgelei word, deur ’n bekende filter te gebruik, van die onbekende ‘tyd voorwerp’ nl. die inset puls. Ons het die iteratiewe algoritme wat die ‘tyd voorwerp’ rekonstrueer aangepas om ook die monster puls te vind en ons wys dat ons hierdie metode suksesvol kan gebruik om laser pulse te karakteriseer