Mr T. J. Sono, an MSc student during the period January 2001 to January 2003, developed an apparatus to measure the pressure and temperature dependence of the electric-field induced birefringence (or electro-optic Kerr effect) in gases. Mr Sono obtained experimental results for dimethyl ether at a wavelength of 632.8 nm resulting in polarizability tensor components, first and second Kerr hyperpolarizabilities, and second Kerr-effect virial coefficients for this particular molecular species. One of the primary concerns of this thesis has been to obtain new measured Kerr-effect data for dimethyl ether and for trifluoromethane over a range of temperature. The cell has been calibrated using hydrogen as a primary standard, and has been carefully aligned to avoid multiple reflections of the incident laser beam off the closely-spaced electrode surfaces. The data has been analyzed to extract values of the polarizability anisotropy and the second Kerr hyperpolarizability for these molecules. In addition, precise values for the second Kerr-effect virial coefficients have been obtained from measurements of the Kerr effect a function of pressure. The molecular-tensor theory of the second Kerr-effect virial coefficient BK is reviewed. This theory describes the effects of intermolecular interactions on the molar Kerr constant, and it has been used to compute BK for dimethyl ether and trifluoromethane over the experimental temperature range. Agreement between experiment and theory is generally good. BK for ammonia has also been calculated, and compared to recent measured data found in the literature. The theory of the Cotton-Mouton effect (the magnetic analogue of the Kerr-effect) in a dilute gas is reviewed, and a new molecular-tensor theory describing the effects of molecular pair-interactions is developed. Calculations for a test molecule, namely chloromethane, indicate that density-dependent effects for this molecule are extremely tiny (of the order of 1% for typical experimental pressures). This new theory could be profitably used in selecting molecules which might demonstrate a larger effect which might be more readily measured in the laboratory. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

During the period January 2001 to January 2003, M Sc student Mr Tleyane Jonas Sono developed an apparatus to measure the pressure- and temperature-dependence of the electro-optic Kerr effect (electric-field-induced birefringence) in gases. Mr Sono presented experimental results for dimethyl ether at a wavelength of 632.8 nm, extracting polarizability tensor components, first and second Kerr hyperpolarizabilities, and second Kerr-effect virial coefficients for this molecular species. This thesis has been primarily concerned with a thorough re-investigation of the Keneffect for the dimethyl ether molecule. Of primary concern is the reproducibility of the measured data, which depend upon precise and accurate knowledge of various experimental parameters. These include calibrations of the high-voltage power supply which is used to establish the electric field across the medium, the pressure transducer, the platinum thermistors, as well as the Faraday cell which forms the heart of the compensator. There is also a possibility of the 316-stainless-steel electrodes buckling and warping as they are cycled over ±200°C, leading to variations in the applied field and a consequent hysteresis in the results. In essence, we have been loath to publish our Kerr-effect investigation of dimethyl ether before making a thorough investigation of the reproducibility of our measured data. Here we present our investigations, and compare our new Kerr virial coefficients and the molecular (hyper)polarizability data extracted from them against the previous work of Sono. It will become apparent agreement is excellent, and that the findings for dimethyl ether are now ready for publication. The molecular-tensor theory of the Kerr-effect; including the second Kerr-effect virial coefficient BK, which describes the effects of intermolecular collisions on the molecular Kerr constant; is reviewed. The computed data is compared with the experimental data, yielding good agreement over the full experimental temperature range of 280 to 450 K. Attempts to obtain measured data at 260 K proved fruitless in the present study, though efforts are underway to complete this task. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

No description available.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 159-163). Also available via the Internet.

Proefschrift Rijksuniversiteit Groningen. / Met lit.opg. - Met samenvatting in het Nederlands.

Kwok Chi Hang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- All-Optical Signal Processing in Optical Communications --- p.2 / Chapter 1.2 --- Fiber-Based Optical Kerr Nonlinear Switches --- p.5 / Chapter 1.3 --- Highly Nonlinear Fibers --- p.6 / Chapter 1.4 --- Objectives and Scope of Study --- p.8 / Chapter 1.5 --- Summary --- p.9 / Chapter Chapter 2 --- Optical Nonlinearity --- p.14 / Chapter 2.1 --- Fiber Nonlinearity --- p.15 / Chapter 2.2 --- Dispersion --- p.21 / Chapter 2.3 --- Cross-Phase Modulation --- p.26 / Chapter 2.4 --- Cross-Polarization Modulation --- p.29 / Chapter Chapter 3 --- Fibers: The Nonlinear Media --- p.47 / Chapter 3.1 --- Average Dispersion --- p.48 / Chapter 3.2 --- Longitudinal Dispersion Map --- p.53 / Chapter 3.3 --- Nonlinear Refractive Index and Nonlinear Coefficient --- p.57 / Chapter 3.4 --- Electrostrictive Contribution --- p.62 / Chapter 3.5 --- List of the Fiber Properties --- p.66 / Chapter Chapter 4 --- Multi-Wavelength Nonlinear Signal Processing --- p.69 / Chapter 4.1 --- Challenge --- p.70 / Chapter 4.2 --- Applications --- p.72 / Chapter 4.3 --- Proposed System Application --- p.110 / Chapter Chapter 5 --- Conclusion and Future Work --- p.114 / Chapter 5.1 --- Comparisons between Proposed and Existing Approaches --- p.114 / Chapter 5.2 --- Conclusion of the Dissertation --- p.115 / Chapter 5.3 --- Prospects and Directions of Future Work --- p.117 / Appdenix A Numerical Model for Dispersion Calculation --- p.I / Appdenix B Simulation Model of Wide Band Cross-Polarization Switch --- p.III / Appdenix C Simulation Model of Spectral Filtering under XPM --- p.VI / List of Publications --- p.IX

The continued progress of modern information technology relies on understanding the influence of magnetic anisotropy on magnetic thin films. In this work, two sources of magnetic anisotropy are examined in two different soft ferromagnets: a uniaxial anisotropy induced during the fabrication of Ni80Fe20 and exchange anisotropy, or exchange bias, which occurs at the interface of Ni77Fe14Cu5Mo4/Fe50Mn50 bilayer. A home-built Magneto-optical Kerr effect magnetometer is used to measure the magnetic response of the soft ferromagnetic films and details of its construction are also discussed. A simple model of uniaxial anisotropy is described, then applied, to the uniaxial NiFe film and deviations from the model are critically analyzed. The exchange bias and coercive fields of NiFeCuMo/FeMn are reported for the first time and studied as a function of buffer layer material. The influence of the different buffer layer materials on the magnetization response of the bilayer is explained from a structural standpoint.

In this thesis, the characteristics and the applications of Kerr-like nonlinear optical waveguide structures have been studied. The nonlinear optical waveguide is a medium whose refractive index changes with the electric field intensity. In the characteristics of Kerr-like nonlinear optical waveguide structures, we propose a general method for analyzing the three-layer optical waveguide structure with all nonlinear layers by using modal theory. Based on this method, the analysis of transforming arbitrary nonlinear layer into linear layer can be achieved easily by modifying nonlinear coefficient. All kinds of the transverse electric field distributions and the dispersion relation in the three-layer Kerr-like nonlinear optical waveguide structure have been obtained. In the application of Kerr-like nonlinear optical waveguide structures, the Mach-Zehnder waveguide interferometer structure will be discussed. Based on the asymmetric medium and asymmetric construction, the new all-optical router switching device and dense wavelength division multiplexing device have been proposed. The numerical results show that the proposed structures could function as all-optical switch devices and all-optical dense wavelength division multiplexing device.

Articial spin ice structures are two-dimensional systems of lithographically fabricated lattices ofelongated ferromagnetic islands, which interact via dipolar interaction. These systems have beenshown to be a suitable playground to study the magnetic, monopole-like, excitations, similar tothose in three-dimensional rare-earth pyrochlores. Therefore, such articial structures can be potentialmaterials for investigations of magnetricity [1]. The investigations of these articial spin icestructures stretches from the direct imaging of the magnetic congurations among the islands to indirectinvestigation methods allowing to determine the phase transitions occurring in such systems. Inthis project, square articial spin ice arrays were investigated employing magneto-optical Kerr eectfor the measurement of the magnetic susceptibility. The susceptibility dependence on temperaturewas measured at dierent frequencies of the applied AC magnetic eld for arrays of the dierentisland spacing and at two dierent incident light directions with the respect to the direction of theislands. A peak shift of the real part of susceptibility, χ', with increasing frequency towards thehigher temperatures was observed. Furthermore, a rough estimation of the relaxation times of themagnetic moments in the islands is given by the analysis of the susceptibility data.

The design procedure for ultrafast silicon electro-optic switches using photonic crystals in order optimize the operation of the electro-optic switch is presented. The material medium selected for propagation of the optical signal through the switch is silicon nanocrystals in silica. A patterned slot waveguide with one-dimensional photonic crystals is proposed as the preferred slow light waveguide to be used in the design of the electro-optic switch. The ultrafast quadratic electro-optic Kerr effect is the physical effect utilized, and its analysis for slot waveguides is discussed. The optical structure analysis of the electro-optic switch using a ring resonator is presented and it is shown that the use of a slow light waveguide in the ring resonator can reduce the required externally applied electric field and the radius of the ring resonator.