High-Order-Harmonic-Generation Spectroscopy With An Elliptically Polarized Laser Field,
2012
Voronezh State University, Russia
High-Order-Harmonic-Generation Spectroscopy With An Elliptically Polarized Laser Field, M. V. Frolov, N. L. Manakov, T. S. Sarantseva, Anthony F. Starace
Anthony F. Starace Publications
Analytic formulas describing high-order-harmonic generation (HHG) by atoms in an intense laser field with small ellipticity are obtained quantum mechanically in the tunneling limit. The results show that factorization of the HHG yield in terms of an electron wave packet and the photorecombination cross section (PRCS) is valid only for s states of a bound atomic electron, whereas the HHG yield for p states involves two different atomic parameters. For the latter case, elliptic HHG spectroscopy enables one to retrieve both the energy and angular dependence of the PRCS of the target atom, as we illustrate for the case of …
Passive Ranging Using A Dispersive Spectrometer And Optical Filters,
2012
Air Force Institute of Technology
Passive Ranging Using A Dispersive Spectrometer And Optical Filters, Jacob A. Martin
Theses and Dissertations
Monocular passive ranging using atmospheric oxygen absorption has been demonstrated in the past using an FTS. These instruments are very sensitive to vibration making them di cult to use on an airborne platform. This work focuses on whether passive ranging can be done with instruments that are easier to deploy. Two potential instruments are tested and compared: a diffraction grating spectrometer and optical filters. A grating spectrometer was able to estimate range to within 5% for a static solid rocket motor ring at a distance of 910 m using the NIR absorption band of oxygen. Testing at shorter ranges produced …
Threshold Effects In Strong-Field Ionization: Energy Shifts And Rydberg Structures,
2012
University of Warsaw, Poland
Threshold Effects In Strong-Field Ionization: Energy Shifts And Rydberg Structures, Katarzyna Krajewska, Ilya I. Fabrikant, Anthony F. Starace
Anthony F. Starace Publications
The behavior of strong-field ionization rates of neutral atoms in the vicinity ofmultiphoton ionization thresholds is analyzed using formal collision theory.Our approach,which accounts nonperturbatively for effects of an intense laser field, shows that the ionization rates have a nearly constant behavior below and above each multiphoton threshold and that between such thresholds there are an apparently finite number of rapid oscillations due to resonances with laser-field-modified Rydberg states. This pattern is typical for any atomic target, as we illustrate specifically for hydrogen and neon atoms. The flat behavior of the ionization yield near multiphoton thresholds gives the appearance of an …
Spectral Engineering Of Optical Fiber Preforms Through Active Nanoparticle Doping,
2012
Clemson University
Spectral Engineering Of Optical Fiber Preforms Through Active Nanoparticle Doping, T. Lindstrom, E. Garber, D. Edmonson, T. Hawkins, Y. Chen, G. Turri, M. Bass, J. Ballato
Publications
Europium doped alkaline earth fluoride [Eu:AEF2 (AE = Ca, Sr, Ba)] nanoparticles were synthesized and systematically incorporated into the core of modified chemical vapor deposition (MCVD)-derived silica-based preforms by solution doping. The resulting preforms were examined to determine the impact of the nanoparticles chemistry on the spectroscopic behavior of the glass. The dominant existence of Eu3+ was demonstrated in all preforms, which is in contrast to conventional solution doped preforms employing dissolved europium salts where Eu2+ is primarily observed. Raman spectroscopy and fluorescence lifetime measurements indicated that the nanoparticles composition is effective in controlling, at a local chemical and structural …
Al6h18: A Baby Crystal Of Γ -Alh3,
2012
McNeese State University
Al6h18: A Baby Crystal Of Γ -Alh3, B. Kiran, Anil K. Kandalam, Jing Xu, Y. H. Ding, M. Sierka, K. H. Bowen, H. Schnöckel
Physics & Engineering Faculty Publications
No abstract provided.
Hohenberg-Kohn Theorem Including Electron Spin,
2012
Ningbo University
Hohenberg-Kohn Theorem Including Electron Spin, Xiao-Yin Pan, Viraht Sahni
Publications and Research
The Hohenberg-Kohn theorem is generalized to the case of a finite system of N electrons in external electrostatic epsilon(r) = -del nu(r) and magnetostatic B(r) = del x A(r) fields in which the interaction of the latter with both the orbital and spin angular momentum is considered. For a nondegenerate ground state a bijective relationship is proved between the gauge invariant density rho(r) and physical current density j(r) and the potentials {nu(r), A(r)}. The possible many-to-one relationship between the potentials {v(r), A(r)} and the wave function is explicitly accounted for in the proof. With the knowledge that the basic variables …
Equilibrium Magnetic States In Individual Hemispherical Permalloy Caps,
2012
Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden
Equilibrium Magnetic States In Individual Hemispherical Permalloy Caps, Robert Streubel, Volodymyr P. Kravchuk, Denis D. Sheka, Denys Makarov, Florian Kronast, Oliver G. Schmidt, Yuri Gaididei
Robert Streubel Papers
The magnetization distributions in individual soft magnetic permalloy caps on non-magnetic spherical particles with sizes ranging from 50 to 800nm are investigated. We experimentally visualize the magnetic structures at the resolution limit of the x-ray magnetic circular dichroism photoelectron emission microscopy (XMCD-PEEM). By analyzing the so-called tail contrast in XMCD-PEEM, the spatial resolution is significantly enhanced, which allowed us to explore magnetic vortices and their displacement on curved surfaces. Furthermore, cap nanostructures are modeled as extruded hemispheres to determine theoretically the phase diagram of equilibrium magnetic states. The calculated phase diagram agrees well with the experimental observations. © 2012 American …
Serpentine Low Loss Trapezoidal Silica Waveguides On Silicon,
2012
University of Southern California
Serpentine Low Loss Trapezoidal Silica Waveguides On Silicon, Xiaomin Zhang, Mark Harrison, Audrey Harker, Andrea M. Armani
Engineering Faculty Articles and Research
We report the fabrication and characterization of straight and serpentine low loss trapezoidal silica waveguides integrated on a silicon substrate. The waveguide channel was defined using a dual photo-lithography and buffered HF etching and isolated from the silicon substrate using an isotropic silicon etchant. The waveguide is air-clad and thus has a core-cladding effective index contrast of approximately 25%. Measured at 658, 980 and 1550nm, the propagation loss was found to be 0.69, 0.59, and 0.41dB/cm respectively, with a critical bending radius less than 375μm. The waveguide’s polarization behavior was investigated both theoretically and experimentally. Additionally, the output power shows …
Progress On: “Coherent Terahertz Acoustic Phonon Scattering: Novel Diagnostic For Erosion In Plasma Thruster Discharge Chamber Walls",
2012
Marshall University
Progress On: “Coherent Terahertz Acoustic Phonon Scattering: Novel Diagnostic For Erosion In Plasma Thruster Discharge Chamber Walls", Thomas E. Wilson, Iain D. Boyd
Physics Faculty Research
The study is based on the success in obtaining the first experimental evidence for the direct excitation of coherent nanosecond-pulsed high-frequency acoustic phonons in semiconducting doping superstructures by electromagnetic fields of the same frequency. Acoustic phonons are detected by a superconducting bolometer, with nanosecond resolution, at the appropriate time-of-flight across a (100) silicon substrate for ballistic longitudinal phonons when a silicon delta-doped doping superlattice is illuminated with grating-coupled nanosecond-pulsed 246-GHz laser radiation with an approximate power density of 1 kW/mm2. The absorbed phonon power density in the bolometer detector is estimated to be 10 μW/mm2, in …
Leds And Astronomy,
2012
National Optical Astronomy Observatory
Leds And Astronomy, Britny N. Delp, Stephen M. Pompea
STAR Program Research Presentations
Using a Czerny-Turner spectrometer, 45 different types of outdoor lights were categorized. These spectra were used to determine how useful the light is to human eyes and how dark skies friendly these lights are. Dark skies friendly lighting means that little to no light shines above a right angle to the light, and should emit as little as possible below 500nm (green) wavelengths. The short wavelengths present a problem to astronomers in the form of Rayleigh scattering. The following criterion were used in selecting the best source for urban and rural lighting: color rendition measured by color rendering index (CRI), …
Polarization Properties Of Maxwell-Gauss Laser Beams,
2012
University of Arkansas, Fayetteville
Polarization Properties Of Maxwell-Gauss Laser Beams, Jessica Patricia Conry
Graduate Theses and Dissertations
Laser beams are wave-like optical disturbances. They are characterized by a dominant direction of propagation and a finite extent transverse to the direction of propagation. Many characteristics of laser beams can be described in terms of a scalar function multiplied by a constant vector, which can be real (for linear polarization) or complex (for elliptical polarization). The scalar function is a solution to the paraxial scalar wave equation. This scalar description, however, fails to describe the polarization and focusing characteristics of laser beams correctly. For a correct accounting of these characteristics, the electric and magnetic fields associated with laser beams …
Modeling Transmission Of Photonic Crystal Waveguide Modes Enhanced By Kerr Nonlinearity,
2012
Western Michigan University
Modeling Transmission Of Photonic Crystal Waveguide Modes Enhanced By Kerr Nonlinearity, Buddhi M. Rai
Dissertations
Nonlinear modes of electromagnetic fields propagating in photonic crystal systems have been studied by implementing various computer simulation techniques using electromagnetic theory. The fundamentals of simulation of photonic crystals are analyzed using general purpose methodologies such as the FDTD or PWE methods. Information derived from the underlying physical insights into the systems could be utilized to describe the control mechanisms over the propagation of the modes around impurities in the photonic crystal lattice. The impurities trap the resonantly localized electromagnetic modes having a frequency in a stop band of the photonic crystal, suggesting novel optical controls in the photonic crystal …
Suppression Of Pair Creation Due To A Steady Magnetic Field,
2012
China University of Mining and Technology
Suppression Of Pair Creation Due To A Steady Magnetic Field, W Su, M Jiang, Z Q. Lv, Rainer Grobe, Qichang Su
Faculty publications – Physics
We investigate the electron-positron pair creation process in a supercritical static electric field in the presence of a static magnetic field that is perpendicular. If both fields vary spatially in one direction the dynamics can be reduced to a set of one-dimensional systems. Using a generalized computational quantum field theoretical procedure, we calculate the time dependence of the spatial density for the created electrons. In the presence of the magnetic field, a significant amount of suppression of pair creation is observed in the simulations and confirmed by an analytical analysis for the limits of short-range fields and long interaction times. …
The Effect Of Polarization And Ingan Quantum Well Shape In Multiple Quantum Well Light Emitting Diode Heterostructures,
2012
California Polytechnic State University, San Luis Obispo
The Effect Of Polarization And Ingan Quantum Well Shape In Multiple Quantum Well Light Emitting Diode Heterostructures, Patrick M. Mcbride
Master's Theses
Previous research in InGaN/GaN light emitting diodes (LEDs) employing semi-classical drift-diffusion models has used reduced polarization constants without much physical explanantion. This paper investigates possible physical explanations for this effective polarization reduction in InGaN LEDs through the use of the simulation software SiLENSe. One major problem of current LED simulations is the assumption of perfectly discrete transitions between the quantum well (QW) and blocking layers when experiments have shown this to not be the case. The In concentration profile within InGaN multiple quantum well (MQW) devices shows much smoother and delayed transitions indicative of indium diffusion and drift during …
Gaussian Beam Steering On A Target Plane Via High Speed Orthogonal Mirror-Mounted Galvanometers,
2012
California Polytechnic State University - San Luis Obispo
Gaussian Beam Steering On A Target Plane Via High Speed Orthogonal Mirror-Mounted Galvanometers, Keith Gresiak
Physics
No abstract provided.
Study Of The Structure Of 9C Via Single Neutron Transfer,
2012
Western Michigan University
Study Of The Structure Of 9C Via Single Neutron Transfer, Scott T. Marley
Dissertations
This thesis describes a study of the nucleus 9C, produced in the single-neutron transfer reaction d(10C, t) 9C using a radioactive 10C beam. The structure of the neutron-deficient nucleus 9C is poorly known. Only a few excited states have been observed and no information exists of their single-particle characteristics. The measured ground-state magnetic dipole moment of 9C is anomalously small and could imply large contributions from sd-shell orbitals in the ground-state wave function. The positions of the 9C excited states and their single-particle properties are vital to furthering the …
Magnetic Vortices On Closely Packed Spherically Curved Surfaces,
2012
Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden
Magnetic Vortices On Closely Packed Spherically Curved Surfaces, Robert Streubel, Denys Makarov, Florian Kronast, Volodymyr Kravchuk, Manfred Albrecht, Oliver G. Schmidt
Robert Streubel Papers
We investigate the change of magnetic vortex states driven by curvature. The equilibrium state and magnetization reversal of soft magnetic permalloy (Py, Ni 80Fe 20) caps on self-assembled spherical particles with diameters of 100, 330, and 800 nm are investigated, revealing the vortex ground state for individual caps and closely packed cap arrays. The magnetic coupling between vortices is substantially reduced due to the shape of the cap as apparent in a much weaker dependence of the magnetization reversal process on the separation distance. Interestingly, the remaining coupling is still sufficiently large to introduce chirality frustrated vortex states …
Magnetic Ordering And Structural Phase Transition In Strained Ultrathin Srruo3/Srtio3 Superlattice,
2012
Indiana State University
Magnetic Ordering And Structural Phase Transition In Strained Ultrathin Srruo3/Srtio3 Superlattice, Mingquiang Gu, Xiaoshan Wu, Guoping Zhang
Symposium 2012
No abstract provided.
Numerical Simulations Of Chirped Excitation,
2012
University of Connecticut - Storrs
Numerical Simulations Of Chirped Excitation, Benjamin Iannitelli
Honors Scholar Theses
In this project I developed a general method of finding the optimal laser excitation for an ensemble of two-level atoms with the primary goal of exciting as many atoms as possible, as quickly as possible, for as long as possible, in order of decreasing priority. Specifically, I simulated the laser excitation of a collection of Rubidium-87 atoms from (n=5, L=0, S=1/2, J=1/2) to (n=5, L=1, S=1/2, J=3/2), by finding numerical solutions to the optical Bloch equations. I optimized the parameters of a linear chirp paired with a Gaussian intensity pulse first neglecting and then including spontaneous emission, and then for …
Hohenberg-Kohn And Percus-Levy-Lieb Proofs Of Density-Functional Theory,
2012
CUNY Graduate Center and CUNY Brooklyn College
Hohenberg-Kohn And Percus-Levy-Lieb Proofs Of Density-Functional Theory, Viraht Sahni, Xiao-Yin Pan
Publications and Research
The premise of density-functional theory is that knowledge of the ground-state density uniquely determines the Hamiltonian, and thereby, via solution of the corresponding time-independent Schrodinger equation, all the properties of the system. The density therefore constitutes a basic variable of quantum mechanics. There are at present two paths from the density to the Hamiltonian: the Hohenberg and Kohn proof of the bijectivity between the external potential and the basic variable, and the Percus, Levy, and Lieb constrained-search proof. We argue the Hohenberg- and Kohn-type proof to be the more fundamental, and that this is the case in general when both …
