The quasi-P wave in anisotropic solids is of practical importance in obtaining maximal imaging resolution in seismic exploration. The geometrical optics term in the asymptotic expansion for the wave characterizes the high frequency part of the quasi-P wave by using two functions: a phase (traveltime) function satisfying an eikonal equation and an amplitude function satisfying a transport equation. I develop theories and numerical methods for constructing the geometrical optics term of quasi-P waves in general anisotropic solids. The traveltime corresponding to the downgoing wave satisfies a paraxial eikonal equation, an evolution equation in depth. This paraxial eikonal equation takes into account the convexity of the quasi-P slowness surface and thus has a built-in reliable indicator of the ray velocity direction. Therefore, high-order finite-difference eikonal solvers are easily constructed by utilizing Weighted Essentially NonOscillating (WENO) schemes. Because the amplitude function is related to second-order derivatives of the traveltime, a third-order accurate eikonal solver for traveltimes is necessary to get a firstorder accurate amplitude. However, the eikonal equation with a point source has an upwind singularity at the source which renders all finite-difference eikonal solvers to be first-order accurate near the source. A new approach combining an adaptive-gridding strategy with WENO schemes can treat this singularity efficiently and can yield highly accurate traveltimes and amplitudes for both isotropic and anisotropic solids. A variety of numerical experiments verify that the new paraxial eikonal solver and adaptive-gridding-WENO approach are accurate and efficient for capturing the anisotropy. Therefore, the two new methods provide tools for constructing the geometrical optics term of the quasi-P wave in general anisotropic solids.

The diode laser system for laser cooling on the 1S 0 → 3P1 intercombination line of strontium discussed in this thesis allows us to cool and trap an atomic strontium sample to 15 muK. Samples in this temperature range are useful for the development of the next generation of atomic frequency standards, cold collision studies, and as a step towards quantum degeneracy. This laser system consists of a Littrow configuration external-cavity diode laser, which is frequency locked to a high finesse cavity. The cavity is subsequently locked to an absorption feature to produce a few mW of tunable, stabilized, single mode power at the target wavelength. We present the design and characterization of this system, including a linewidth measurement of 70 kHz, as well as preliminary results from cooling and trapping.

This thesis describes the construction and characterization of a high energy, tunable, pulsed dye laser that is used to make ultracold strontium plasma. In order to make ultracold plasma, we cool and trap strontium atoms in a magneto-optical trap (MOT) and then photoionize them with the dye laser. The dye laser is pumped by high-energy 355nm pulses from a commercial Nd:YAG laser and it gives out 10ns pulses of 400--415nm light with up to 50mJ/pulse. We will discuss the lasers spectrum, wavelength calibration, output power and efficiency for photoionizing strontium.

<p> Nuclear spin induced optical rotation (NSOR) is a novel technique for the detection of nuclear magnetic resonance (NMR) via optical rotation instead of conventional pick-up coil. Originating from hyperfine interactions between nuclei and orbital electrons, NSOR provides a new method to reveal nuclear chemical environments in different molecules. Previous experiments of NSOR detection have poor signal-to-noise ratio (SNR), which limits the application of NSOR in chemistry. In this work, based on a continuous-wave NMR scheme at a low magnetic field (5 G), we employ a multi-pass cavity and a 405 nm laser to improve the sensitivity of NSOR. By performing precision measurements of NSOR detection in a range of pure liquid organic chemicals, we demonstrate the capability of NSOR to distinguish 1H signals in different chemicals, in agreement with the first-principles quantum mechanical calculations. The NSOR of 19F is also measured at low fields with high SNR, showing that heavy nuclei have higher optical rotation signals than light nuclei. </p><p> In addition, in order to obtain NSOR at different chemical sites in the same molecule via chemical shift, we make efforts to develop a novel scheme based on liquid-core hollow fiber for the detection of NSOR under high magnetic fields. By coiling a long liquid-core fiber densely for many loops around a small rod combined with RF coils, it is possible to measure optical rotation signals inside a narrow-bore superconducting magnet. Manufactured by filling liquids into capillary tubings, those liquid-core fibers perform like multimode step-index fibers, and thereby exhibit linear birefringence and depolarization, significantly reducing the light polarization for the measurement of optical rotation. According to our attempts, it is possible to suppress the linear birefringence by filling chiral liquids in hollow fibers, and approach near single-mode operation by means of launching light beam into the fiber core under the mode match condition. Although some issues of hollow fibers obstruct the final measurement of high-frequency NSOR, our work on the liquid-core fiber provides the basis for future fiber-based NSOR experiments under high magnetic fields.</p>

No description available.

Due to the unique rheological properties of colloidal gels, gelation of colloidal suspensions has become increasingly important to fundamental investigations, as well as to technological applications. Recent experimental approaches are mainly focused on the bulk properties of colloidal gels, using methods of static and dynamic light scattering and shear rheometry. This thesis describes the development of a system for measuring the mechanical properties of colloidal gels with optical tweezers. / We make colloidal gels out of polystyrene beads of two different sizes, diameters of 3.5mum or 62nm respectively. Investigation of the colloidal gels under the light microscope shows the fractal nature of the gel structure while macroscopic study confirms that the gelation process of the smaller polystyrene beads is faster than that of the bigger polystyrene beads. We were also able to generate a phase diagram of the gelation process. / We successfully assembled the main instrument, a time-sharing single beam optical tweezers, and calibrated the lateral stiffness of the optical trap. Our optical tweezers setup is used to study the polystyrene gel and it has many more applications in colloidal samples. The strong 3D optical trapping highlights the optical tweezers as a powerful technique suitable for further investigation of colloidal samples.

<p> Dielectric microspheres with diameters (<i>D</i>) on the order of several wavelengths of light have attracted increasing attention from the photonics community due to their ability to produce extraordinarily tightly focused beams termed "photonic nanojets," to be used as microlenses for achieving optical super-resolution or to develop sensors based on whispering gallery mode resonances. In this dissertation, we study the optical properties of more complicated structures formed by multiple spheres which can be assembled as linear chains, clusters or arrays, integrated with waveguides or embedded inside other materials to achieve new optical properties or device functionalities. </p><p> For linear chains of polystyrene microspheres (n=1.59), we observed a transition from the regime of geometrical optics (at <i>D</i>>20 times the wavelength ) to the regime of wave optics (at <i>D</i>&lt;20 times the wavelength ). We showed that this transition is accompanied by a dramatic change of focusing and optical transport properties of microsphere-chain waveguides. The results are found to be in qualitative agreement with numerical modeling. </p><p> We developed, designed, and tested a single-mode microprobe device based on spheres integrated with a waveguide for ultraprecise laser surgery. Our design is optimized using a hollow-core microstructured fiber as a delivery system with a single-mode Er:YAG laser operating at an illuminating wavelength of 2.94 micron. Using a high-index (<i>n</i>&sim;1.7-1.9) microsphere as the focusing element we demonstrate experimentally a beam waist of &sim;4 times the wavelength, which is sufficiently small for achieving ultraprecise surgery. </p><p> For embedded microspherical arrays, we developed a technology to incorporate high-index (<i>n</i>&sim;1.9-2.1) spheres inside thin-films made from polydimethylsiloxane (PDMS). We showed that by using liquid lubrication, such thin-films can be translated along the surface to investigate structures and align different spheres with various objects. Rigorous resolution treatment was implemented and we demonstrated a resolution of &sim;1/7 of the wavlength of illumination, which can be obtained by such thin-films. </p><p> We experimentally demonstrated that microspheres integrated with mid-IR photodetectors produce up to 100 times photocurrent enhancement over a broad range of wavelengths from 2 to 5 microns. This effect is explained by an increased power density produced by the photonic jet coupled to the active device layers through the photodetector mesas. The photocurrent gain provided by photonic jets is found to be in good agreement with the numerical modeling.</p>

In this thesis, we experimentally test fundamental properties of quantum mechanics, namely non-locality (in the form of three new families of Bell's inequalities) and the symmetry of envariance. To accomplish these we use a Sagnac source of polarization entangled photon pairs. In chapters one and two we discuss the relevant background information in quantum information theory, nonlinear optics, experimental realization of polarization entangled photons and a trouble-shooting and maintenance guide for a Saganc source. In chapter three we experiment with a set of three newly derived families of Bell's inequalities. These three families are predicted to yield the largest volume of violation of the local hidden variable models (LHVM). Our experimental results are in good agreement with those predictions and therefore, represent the largest volume of experimental violation of LHVM to date. We showed a violation of up to 30 sigma from what is predicted by LHVM, and our results followed closely to the predictions of quantum mechanics. In chapter four we experimentally test envariance, an assisted-symmetry exhibited by specifi c quantum systems. Envariance is a fundamental property in the quantum world that has lacked, until now, extensive experimental study. The symmetry has ramifi cations in the foundations of quantum mechanics, and plays an integral role in a proof of Born's rule [1]. Our results serve as a benchmark the property of envariance. We show that experimental quantum states can be (99.66+/- 0.04)% envariant over a wide range of transformations, as measured using the average quantum fi delity [2], and (99.963 +/- 0.005)% as measured using a modifi ed average Bhattacharya Coeffi cient [3], a measure of the overlap of two probability distributions.

<p> It is important to characterize surface and transmitted wavefront errors in terms of the spatial content. The errors are typically analyzed in three spatial domains: figure, ripple (or mid-spatial frequency) and roughness. These errors can affect optical system performance. For example, mid-spatial frequency errors can lead to self-focusing and power loss in a high-power laser system. Currently, power spectral density (PSD) is used for the spatial content characterization in high-end optics, although there are potential pitfalls. For example, the low spatial content is removed before calculation, only a small fraction of surface data are used, and the results are sensitive to details like the windowing.</p><p> As an alternative, the structure function (SF) does not have such problems. It is the expectation of the squared height difference as a function of separation. The linear SF has been used in astronomy and captures data of all spatial frequencies. However, it does not capture anisotropy on the surface. The two-quadrant area SF introduced in this dissertation obviates this problem. It is computationally correct for any arbitrary aperture over all spatial content with anisotropic information. </p><p> This dissertation discusses some computational issues of the SF, which includes the calculation of the linear / area SF, sliding sampling method for large numbers of points within the aperture, analysis of periodic errors, and connection between the linear SF and area SF. </p><p> Moreover, the relationships between the SF and other surface characterization techniques (Zernike polynomials, autocorrelation function (ACF), PSD, and RMS gradient) have been investigated. It turns out that the linear SF of the sum of the Zernike terms only equals to the sum of the linear SF of each of the Zernike polynomials with different azimuthal frequencies. However, this theorem does not apply to the area SF. </p><p> For stationary surfaces, the SF contains similar information as ACF, but it provides better visualization. The SF is computationally correct for any arbitrary aperture shape without extra processing, while the PSD always needs additional mathematical processing. After connecting the SF to the RMS gradient, the SF slope at the origin has been evaluated. </p><p> Use of a SF to specify optical surfaces over the full range of spatial frequencies of interest implies the combination of data from instruments with substantially different lateral resolutions. This research shows the combination of data from a Fizeau and a coherence scanning interferometer (CSI) for various precision surfaces. The investigation includes the connection method of the coordinate systems between the Fizeau data and the CSI sub-aperture data, the convergence of the averaged SF of sub-aperture samples, the uncertainty analysis, and the effect of the instrument transfer function (ITF). </p><p> In addition, the SF was used to explore two typical noise contributions (electronic noise and air turbulence) in phase shifting interferometry. Based on dynamic measurements, the SF was used to analyze the spatial components of a diamond turned surface after the compensation machining. </p><p> In summary, the SF is a useful tool to specify and characterize the spatial content of optical surfaces and wavefronts.</p>

A comprehensive computer package for the calculation and simulation of charged-particle dynamics in electromagnetic fields has been developed and tested. The program provides a user-friendly and flexible interface for visualizing particle dynamics using phase space diagrams, which are essential for complete understanding of a beam optics system. The program performs an accurate finite difference computation of a user-defined boundary value problem (in the form of a grid) followed by a high-order Runge-Kutta numerical integration of the equations of motion to evaluate the particle dynamics within the field. The program is unique in its combination of these flexible finite calculation techniques with the parallel processing of particle ensembles in order to display phase space diagrams. / After extensive testing, the program has been used to design a low emittance ion source and an ion beam deceleration system for high-efficiency ion collection. The program has also been used to analyze a radiofrequency quadrupole collisional focusing system using ion mobility concepts.