Thesis (Ph. D.)--Michigan State University. Dept. of Chemistry, 2008. / Title from PDF t.p. (viewed Sept. 10, 2009). Includes bibliographical references. Also issued in print.

Thesis (PhD)--Montana State University--Bozeman, 2010. / Typescript. Chairperson, Graduate Committee: Aleksander Rebane. Includes bibliographical references (leaves 126-144).

This thesis presents analytic and computational advances in the prediction of perturbative nonlinear optical spectroscopies. The contributions of this thesis are packaged together in an open source, freely available piece of software called ultrafast spectroscopy suite (UFSS). It is designed to automatically simulate nonlinear optical spectroscopies for any phase-matching or phase-cycling condition, including finite pulse effects. UFSS includes an algorithm called the diagram generator (DG) that automates the process of writing out all of the Feynman diagrams that contribute to a desired phase-matching or phase-cycling condition, and includes all pulse overlap diagrams when relevant, paving the way toward automation of perturbative calculations. Further, many diagrams can be automatically combined into composite diagrams, giving an exponential decrease in computation time of high-order calculations. Composite diagrams even allow for the efficient study of Rabi oscillations as a function of pulse amplitude, by summing many orders of perturbation theory. The perturbative calculations are done using a novel algorithm presented in this thesis called Ultrafast Ultrafast spectroscopy (UF2). UF2 is an efficient method for determining diagrammatic contributions to spectra including arbitrary (whether analytical or experimentally measured) pulse shapes. It uses the speed of the fast Fourier transform to be as much as 500 times faster than direct propagation techniques for small model Hamiltonians (for Hamiltonian dimension of 100 or less). UF2 outperforms direct propagation techniques for a wide range of model systems, with the speed boost diminishing as the dimension of the model Hamiltonian increases. UF2 can predict spectra for any model system whose relevant Hilbert space that can be described using a finite basis and that can be diagonalized numerically, and users are free to specify their own model. UFSS includes a model generator that generates Hamiltonians and Liouvillians of vibronic systems, allowing users to easily simulate NLOSs for a wide range of model system parameters. UFSS is a fully functional piece of software for simulating any NLOS, to any desired order in perturbation theory.

Nonlinear optics is a field with new applications being regularly discovered, which leads to a growing interest in computing these properties. In this work, we attempt to determine new methods of computationally determining the properties of biologically relevant systems. We do so through testing a novel finite-field method to compute these properties. To facilitate the computation of molecular energies required for finite-field calculations, we tested a hypergeometric resummation scheme. Together, these projects form a strong step into being able to compute the nonlinear optical properties for larger systems of biological relevance. / Thesis / Master of Science (MSc)

This dissertation deals with the characterization of the nonlinear absorption and refraction of two representative metallophthalocyanine dyes: chloro aluminum phthalocyanine dissolved in methanol, referred to as CAP, and a silicon naphthalocyanine derivative dissolved in toluene, referred to as SiNc. Using the Z-scan technique, the experiments are performed on both the picosecond and nanosecond timescales at a wavelength of 0.532 μm.

No description available.

A detailed understanding of the corneal biomechanical response is an important prerequisite to understanding corneal diseases such as keratoconus and for placing the empirical equations used in refractive surgery on a physical basis. We have assembled a combined nonlinear optical microscopy (NLOM) and optical coherence microscopy (OCM) imaging system to simultaneously capture coregistered volumetric images of corneal morphology and biochemistry. Fudicial markers visible in the OCM volume enabled the calculation of strains for multiple depth layers in rabbit cornea. The results revealed a depth dependent strain distribution, with smaller strains in the anterior stroma and larger strains in the posterior stroma. The stress-strain curves can be grouped readily by depth into three groups: anterior (~20%), transitional mid (~40%), and posterior (~40%). Cross-sectional images of collagen lamellae, visible in NLOM, showed inhomogeneous collagen structure and its response to intraocular pressure along the anterior-posterior direction. The inhomogeneities correlate well with the noted heterogeneous corneal mechanical properties. The combined NLOM-OCM system can measure corneal microstructure and mechanical response uniquely, thus providing a microstructural understanding of corneal response to changes of collagen structure.

In this study, we extend the rigidity and resonance of benzobisthiazo- le for the application as second-order nonlinear optics. A novel nonlinear optical polyimide (NLO-PI) containing side-chained benzobisthiazole- based chromophore has been synthesized. A hydroxyl- containing PI (PHI) was first prepared using direct thermal imidization of 2,4-diaminophenol dihydrochloride and 4,4¡¦-(hexafluoroisopropylidene)diphthalic anhydride; the benzobisthiazole-based chromophore was then prepared using 2,5-diamino- 1,4-benzenedithiol dihydrochloride as the starting monomer. The final NLO-PI was obtained by the Mitsunobu reaction via ether linkage between PHI and the chromophore. This ether linkage is expected to provide chain flexibility for better orientation under electric field during poling. Formation of benzobisthiazole-based chromophore and the corresponding NLO-PI was evidenced by FTIR and UV-vis spectra. TGA and TMA reveal a thermal decomposition temperature and a glass transition temperature as high as 576 and 324oC, respectively. The electrooptic coefficient of the NLO-PI at a wavelength of 630nm was found to be r33 = 6.62 pm/V.

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.

The achievement of thermally stable second-order nonlinear optical (NLO) coefficients in polymers is an important but elusive goal in obtaining useful materials for commercial devices. In order to demonstrate the effect of photocrosslinkable groups on enhancement of stability of NLO properties, a series of NLO polymers were investigated, which contain side-chain NLO chromophores with a variable number of crosslinkable methacrylate groups attached to the chromophore opposite the main chain attachment point. Following electric field poling, polymers were crosslinked by irradiating polymer samples containing a photoinitiator. Decay of second-order NLO properties was measured by second harmonic generation (SHG), and stability of SHG coefficients was significantly enhanced after photocrosslinking for polymers containing multiple crosslinkable groups on the chromophore. Addition of reactive diluents further enhanced stability. The enhancement of thermal stability demonstrates the efficacy of photocrosslinking and suggests that the stability improvements may carry over to systems with more efficient chromophores and more stable polymer backbones. The addition of photocrosslinkable materials is also exploited in photoresists to mitigate alignment limitations on flexible substrates during photolithographic patterning by enabling imaging of two device layers in a single lithographic exposure. To facilitate the simultaneous patterning of two device layers, a new photoresist system was developed which is able to store and transfer two images concurrently. The dual-tone photoresist system has the ability to store two independent latent images, distinguished by the incident exposure light wavelength, while remaining compatible with reactive ion etch image transfer processes. A modified chemically amplified photoresist for 193 nm lithography containing an added photobase generator (PBG) leads to a dual-threshold behavior of the dissolution vs. dose contrast curve that enables pitch division of patterned images. To improve these resists, a study of resist components’ effects on line edge roughness and pitch division process windows was performed. The kinetics of two-stage PBGs are compared to single-stage PBGs with a view toward achieving higher acid latent image gradients at the line edge. Application of nuclear magnetic resonance spectroscopy to determine the rate constants for resist components in thin films is demonstrated and discussed as a tool for formulating dual-threshold resists. / text