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Contrasts in Thermal Dffusion and Heat Accumulation Effects in the Fabrication of Waveguides in Glasses using Variable Repetition Rate Femtosecond LaserEaton, Shane 31 July 2008 (has links)
A variable (0.2 to 5 MHz) repetition rate femtosecond laser was applied to delineate the role of thermal diffusion and heat accumulation effects in forming low-loss optical waveguides in borosilicate glass across a broad range of laser exposure conditions. For the first time, a transition from thermal diffusion-dominated transport at 200-kHz repetition rate to strong heat accumulation at 0.5 to 2 MHz was observed to drive significant variations in waveguide morphology, with rapidly increasing waveguide diameter that accurately followed a simple thermal diffusion model over all exposure variables tested. Amongst these strong thermal trends, a common exposure window of 200-mW average power and ~15-mm/s scan speed was discovered across the range of 200-kHz to 2-MHz repetition rates for minimizing insertion loss despite a 10-fold drop in laser pulse energy. Waveguide morphology and thermal modeling indicate that strong thermal diffusion effects at 200 kHz give way to a weak heat accumulation effect at ~1uJ pulse energy for generating low loss waveguides, while stronger heat accumulation effects above 1-MHz repetition rate offered overall superior guiding. The waveguides were shown to be thermally stable up to 800°C, showing promise for high temperature applications. Using a low numerical aperture (0.4) lens, the effect of spherical aberration was reduced, enabling similar low-loss waveguides over an unprecedented 520-um depth range, opening the door for multi-level, three-dimensional, optical integrated circuits. In contrast to borosilicate glass, waveguides written in pure fused silica under similar conditions showed only little evidence of heat accumulation, yielding morphology similar to waveguides fabricated with low repetition rate (1 kHz) Ti-Sapphire lasers. Despite the absence of heat accumulation in fused silica owing to its large bandgap and high melting point, optimization of the laser wavelength, power, repetition rate, polarization, pulse duration and writing speed resulted in uniform, high-index contrast waveguide structures with low insertion loss. Optimum laser exposure recipes for waveguide formation in borosilicate and fused silica glass were applied to fabricate optical devices such as wavelength-sensitive and insensitive directional couplers for passive optical networks, buried and surface microfluidic and waveguide networks for lab-on-a-chip functionality, and narrowband grating waveguides for sensing.
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Laser/microstructure interaction and ultrafast heat transferHeltzel, Alexander John, January 1900 (has links) (PDF)
Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.
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UV laser assisted processing of InP at different ambient conditions with variable number of pulses and fluencesMusaev, Omar. Wróbel, Jerzy. January 2006 (has links)
Thesis (Ph. D.)--Dept. of Physics and School of Computing and Engineering. University of Missouri--Kansas City, 2006. / "A dissertation in physics and telecommunications networking." Advisor: Jerzy Wrobel. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Nov. 1, 2007. Includes bibliographical references (leaves 185-190). Online version of the print edition.
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Origin and processing of laser doppler spectra /Arildsson, Mikael, January 1900 (has links) (PDF)
Diss. Linköping : Univ., 2000.
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Regulation of microvascular blood flow : a clinical and experimental study based on laser Doppler perfusion imaging /Golster, Helena. January 1900 (has links) (PDF)
Diss. (sammanfattning) Linköping : Univ., 2001. / Härtill 5 uppsatser.
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Laser Doppler imaging of patch tests : a methodological and comparative study with visual assessments /Bjarnason, Bolli, January 1900 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 9 uppsatser.
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Planar laser polarisation spectroscopy imaging in combustion /Reppel, Julie-Ann. January 2003 (has links) (PDF)
Thesis (Ph.D.)--University of Adelaide, School of Chemical Engineering and School of Mechanical Engineering, 2004. / "27 September 2003." Includes bibliographical references (leaves xix-xxv ; v. 1).
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Far-field and near-field optical trappingGanic, Djenan. January 2005 (has links)
Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, Centre for Micro-Photonics, 2005. / A thesis submitted for the degree of Doctor of Philosophy, Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, 2005. Typescript. Includes bibliographical references (p. 164-177). Also available on cd-rom.
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Resonant-infrared laser ablation of polymers mechanisms and applications /Johnson, Stephen L. January 2008 (has links)
Thesis (Ph. D. in Physics)--Vanderbilt University, Dec. 2008. / Title from title screen. Includes bibliographical references.
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RESOLFT-Mikroskopie mit photoschaltbaren ProteinenHofmann, Michael. January 2007 (has links)
Heidelberg, Univ., Diss., 2007.
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