Thése--Faculté des sciences de Paris. / "Bibliographie," p. [179]-188.

Diss.--Wittemberg (J.M. Faulhaber, respondent). / At head of title: Q.D.B.V.

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves [484-494]).

Thése--Faculté des sciences de Paris. / "Bibliographie," p. [179]-188.

Thèse--Paris. / Bibliography: p. [111]-114.

<p> Kidney stone disease affects approximately 10% of the U.S. population. Conventional Holmium:YAG infrared laser lithotripsy is a standard minimally invasive treatment that operates based on a photothermal interaction with the main chromophore in tissue being water.</p><p> Our laboratory is exploring the Thulium Fiber laser (TFL) as an alternative to Ho:YAG laser for lithotripsy, due to the TFL&rsquo;s ability to operate at low pulse energies and high pulse rates, producing smaller stone fragments and reduced retropulsion. The TFL also more closely matches a high temperature water absorption peak. Additionally, the improved TFL spatial beam profile enables coupling of laser energy into smaller fibers (50-150-&micro;m-core) than currently used in Ho:YAG lithotripsy.</p><p> TFL ablation rate, ablation threshold, operation time, and vapor bubble dynamics and pressure transients were analyzed and compared to the Ho:YAG laser in all experiments.</p><p> TFL ablation rate was examined at pulse rates up to 500 Hz. Ablation rates scaled linearly with pulse rate and were more effective at higher pulse rates. TFL operation time and ablation rates were found to be more efficient than for Ho:YAG. TFL vapor bubbles were discovered to collapse multiple times along the optical axis of the fiber, while the Ho:YAG laser created a single, larger, bubble that collapsed only once. Due in part to these differing bubble dynamics, lower pressures were observed with the TFL. </p><p> Every experiment was designed to examine the TFL ablation mechanisms and find optimum laser parameters to safely increase stone ablation rates and efficiency.</p><p>

abstract: The interaction of light with nanoscale structures consisting of metal and two-level quantum emitters is investigated computationally. A method of tilting the incoming electromagnetic wave is used to demonstrate coupling between a sinusoidal grating and two-level quantum emitters. A system consisting of metallic v-grooves and two-level emitters is thoroughly explored in the linear regime, where the spatially uniform fields provide a unique means of characterizing the coupling between the v-grooves and emitters. Furthermore, subwavelength spatial effects in the ground state population of emitters in the v-grooves are observed and analyzed in the non-linear regime. Finally, photon echoes are explored in the case of a one-dimensional ensemble of interacting two-level emitters as well as two-level emitters coupled to metallic slits, demonstrating the influence of collective effects on the echo amplitude in the former and the modifcation of the photon echo due to interaction with surface plasmons on the slits in the latter. / Dissertation/Thesis / Doctoral Dissertation Physics 2016

<p> Chip-scale integrated photonic circuits provide an attractive platform for the implementation of many quantum photonic technologies ranging from precise metrology to secure communication and quantum computation. In particular, silicon photonic platforms support micron-scale nonlinear optical sources of non-classical light which can be mass manufactured using the robust fabrication processes pioneered by the CMOS microelectronics industry. Integration of these quantum photonic sources with high-performance classical photonic devices on the same chip is required for truly scalable quantum information technologies. Integrated nonlinear resonators are investigated as sources of quantum mechanically correlated photon pair sources. An all-order dispersion engineering method is presented as a robust design synthesis for micoring sources. In addition, a novel concept of coupled mode dispersion compensation is proposed and demonstrated, providing significantly improved performance characteristics of resonant four-wave mixing sources. Next a photon pair source is demonstrated in a commercial CMOS microelectronics process opening the door to future integration of quantum photonics with electronic logic and control circuits. Classical nonlinear optical measurements of stimulated four-wave mixing are used for the first time to accurately predict the quantum correlations from the same device operating in the photon pair regime. Next the first demonstration of fully on-chip pump rejection is demonstrated with over 95 dB pump extinction improving the figures of merit from previous demonstrations by multiple orders of magnitude, including losses, detected pair rates and size. Finally, proposals for introducing novel degrees of freedom provided by an integrated platform are presented for further improving the performance of both photon pair and classical nonlinear optical sources.</p><p>

<p> Vortices in optical beams have been the subject of extensive study since their status as a generic feature of light was established. They have found extensive use in optical trapping systems, astronomy, microscopy and are being investigated for free space communication systems. Related to optical vortices are correlation vortices in the coherence functions of partially coherent beams. Partially coherent beams have attracted interest as information carriers because of their resistance to scrambling on propagation. However, their analysis is more difficult than that of fully coherent beams due to the necessity of using correlation functions which increases the dimensionality of the integrals needed. </p><p> In this dissertation we demonstrate a complete description of a partially coherent vortex beam on propagation, and derive a new partially coherent beam class based on Laguerre-Gauss beams. We also give an analytic description of diffraction through any polygonal aperture, and demonstrate the triangular aperture case. We conclude with a study of fully coherent, partially coherent and incoherent beams propagated through turbulence.</p><p>

<p> In this dissertation, high-power ytterbium-doped fiber amplifiers designed with advanced waveguide concepts are characterized and power scaled. Fiber waveguides utilizing cladding microstructures to achieve wave guidance via the photonic bandgap (PBG) effect and a combination of PBG and modified total internal reflection (MTIR) have been proposed as viable single-mode waveguides. Such novel structures allow larger core diameters (>35 ?m diameters) than conventional step-index fibers while still maintaining near-diffraction limited beam quality. These microstructured fibers are demonstrated as robust single-mode waveguides at low powers and are power scaled to realize the thermal power limits of the structure. Here above a certain power threshold, these coiled few-mode fibers have been shown to be limited by modal instability (MI); where energy is dynamically transferred between the fundamental mode and higher-order modes. Nonlinear effects such as stimulated Brillouin scattering (SBS) are also studied in these fiber waveguides as part of this dissertation. Suppressing SBS is critical towards achieving narrow optical bandwidths (linewidths) necessary for efficient fiber amplifier beam combining. Towards that end, new effects that favorably reduce acoustic wave dispersion to increase the SBS threshold are discovered and reported. </p><p> The first advanced waveguide examined is a Yb-doped 50/400 &mu;m diameter core/clad PBGF. The PBGF is power scaled with a single-frequency 1064 nm seed to an MI-limited 410 W with 79% optical-to-optical efficiency and near-diffraction limited beam quality (M-Squared &lt; 1.25) before MI onset. To this author&rsquo;s knowledge, this represents 2.4x improvement in power output from a PBGF amplifier without consideration for linewidth and a 16x improvement in single-frequency power output from a PBGF amplifier.</p><p> During power scaling of the PBGF, a remarkably low Brillouin response was elicited from the fiber even when the ultra large diameter 50 &mu;m core is accounted for in the SBS threshold equation. Subsequent interrogation of the Brillouin response in a pump probe Brillouin gain spectrum diagnostic estimated a Brillouin gain coefficient, gB, of 0.62E^-11 m/W; which is 4x reduced from standard silica-based fiber. A finite element numerical model that solves the inhomogenous Helmholtz equation that governs the acoustic and optical coupling in SBS is utilized to verify experimental results with an estimated gB = 0.68E^-11 m/W. Consequently, a novel SBS-suppression mechanism based on inclusion of sub-optical wavelength acoustic features in the core is proposed.</p><p> The second advanced waveguide analyzed is a 35/350 &mu;m diameter core/clad fiber that achieved wave guidance via both PBG and MTIR, and is referred to as a hybrid fiber. The waveguide benefits mutually from the amenable properties of PBG and MTIR wave guidance because robust single-mode propagation with minimal confinement loss is assured due to MTIR effects, and the waveguide spectrally filters unwanted wavelengths via the PBG effect. The waveguide employs annular Yb-doped gain tailoring to reduce thermal effects and mitigate MI. Moreover, it is designed to suppress Raman processes for a 1064 nm signal by attenuating wavelengths > 1110 nm via the PBG effect. When seeded with a 1064 nm signal deterministically broadened to &sim;1 GHz, the hybrid fiber was power scaled to a MI-limited 820 W with 78% optical-to-optical efficiency and near diffraction limited beam quality of M_Squared &sim;1.2 before MI onset. This represents a 14x improvement in power output from a hybrid fiber, and demonstrates that this type of fiber amplifier is a quality candidate for further power scaling for beam combining.</p><p>