Ion-exchanged ring resonators are presented as inexpensive yet highly sensitive integrated optic devices. Several historical applications for ring resonators are outlined then compared with competing technologies. The theory of ring resonator devices is described in detail. The optimum designs for both single and double arm ring resonator configurations are discussed. Ring resonator performance is shown to depend on both the waveguide propagation loss and coupling efficiency. A theoretical model of the ion exchange process is presented and used to determine the processing parameters that minimize bend loss. The coupling efficiency is then modeled for the theoretical waveguide profile. A fabrication recipe for producing high performance ring resonators is developed and the performance of several devices is analyzed. The applications of ring resonator devices for accurate measurement of waveguide birefringence and for rotation sensing are examined. A birefringence measurement technique using ring resonators is presented and the sensitivity of this method is compared to other approaches. The theoretical analysis of the rotational sensitivity of ion-exchanged ring resonator gyroscopes is presented and is shown to have an improvement of two orders of magnitude over previously reported ion-exchanged gyroscopes.

Selectively buried ion-exchanged waveguides in glass are investigated theoretically and experimentally for use in low-loss coupling to other optical media. Selectively buried waveguides (SBWGs) are integrated optic structures in which light makes a transition from a buried waveguide with a maximum refractive index that lies 5-20 μm beneath the glass surface to a surface section with a maximum refractive index that lies at or near the surface. The buried sections provide low propagation losses and convenient coupling to optical fibers. Surface sections allow interaction between the guided mode and a superstrate material; in these sections the glass and superstrate form a composite waveguide in which the optical field propagates in both materials as a single optical mode. Adiabatic transition regions connect buried and surface sections. SBWGs are modelled by use of the finite difference method. The refractive index profile is first computed. The mode profiles and effective indices of the modes that the waveguide supports are then solved. The beam propagation method is applied to determine how the mode changes as it propagates through the SBWG. The transition from a buried to a surface waveguide is modelled, and it is found that the transition is adiabatic and low-loss. The surface section is modelled with a polymer superstrate, and the confinement factor in the polymer is computed. Ag⁺/K⁺ ion exchange is used to fabricate SBWGs, and a thorough experimental investigation of their properties is conducted. Refractive index profiles in buried, surface, and transition regions are measured by use of the refracted near-field method, and it is demonstrated that the maximum refractive index lies approximately 20 μm beneath the surface in buried regions and approximately 3 μm beneath the surface in surface regions. A novel method of simultaneously measuring the mode profile and depth of an ion-exchanged waveguide is presented and applied to SBWGs. Losses in these devices are measured, and the magnitudes of various losses are estimated.

We have completed a new small-animal imaging system, called SemiSPECT, based on eight pixellated cadmium zinc telluride (CdZnTe) gamma-ray detector arrays. The detector is a 2.5 cm x 2.5 cm x 0.15 cm slab having a 64 x 64 pixel array. A read-out application-specific integrated circuit (ASIC) is attached onto the detector via indium-bump bonding, and a -180 V bias is applied onto the detector surface to transport electron-hole pairs generated by gamma-ray interaction. Eight detectors are arranged in an octagonal lead-shielded ring. An eight-pinhole aperture is placed at the center of the ring, and an object is imaged onto each detector through a pinhole. The object can be rotated about a vertical axis to attain sufficient angular projections for tomographic reconstruction. The whole system gantry is compact enough to be placed onto a desktop-sized optical breadboard. Eight front-end boards were developed to detect events, generate list-mode data arrays, and send them to back-end boards. Four back-end boards are utilized to hold the list-mode data arrays and transfer them to a host computer. Eight clock-and-bias boards provide clock and bias signals to the eight ASICs. Eight control-and-bias boards were developed to monitor and control the temperatures on the eight detectors, analog and digital currents supplied to the eight ASICs, and -180 V biases applied to the eight detector surfaces. The spatial resolution provided by SemiSPECT, estimated both based on the system geometry and via the Fourier crosstalk approach, is about 1∼2 mm. The system sensitivity measured with a point source is about 1.53 x 10⁻⁴, and the estimated one from the system geometry is about 1.41 x 10⁻⁴. The energy resolution acquired by summing neighboring pixel signals in a 3 x 3 window is about 10% full-width-at-half-maximum for 140 keV gamma rays. The detectabilities for multiple signal spheres simulating various lesions or organs in a small animal are presented and discussed. A line-phantom image demonstrates that the spatial resolution achieved after tomographic reconstruction is on the order of 1 mm³. A walnut-phantom image is presented to demonstrate how well SemiSPECT reproduces complex structure of an object and compared with a CT image. Images of various organs of mice, such as bone, kidney, and myocardium, and human-lung cancer implanted into a nude mouse are presented and discussed.

This dissertation investigates vector behavior of aberrations for high numerical aperture optical systems using a solid immersion lens (SIL). In order to analyze the system, this dissertation introduces the illumination system transfer function (ISTF), which is a map in the space of the exit pupil that shows reflection and transmission properties of individual plane waves that are emitted from corresponding points in the exit pupil. A vector analysis using ISTF presents the role of propagating and evanescent energy in the SIL systems, where the boundary between the them is defined by total internal reflection. The behavior of third-order aberrations such as coma and astigmatism, are dramatically affected by polarization in high NA systems. The irradiance distribution exhibits significantly different characteristics, depending on how coma or astigmatism is aligned with the incident linear polarized light. Vector effects including diffraction, polarization, and aberration, are used to analyze tolerances along with a comparison to geometrical optics. Apodization in amplitude and phase of the angular spectrum is generated in high NA focusing systems due to the difference in vector transmission and reflection for each plane wave. The size of the incident gaussian beam is effectively reduced at the exit pupil by the amplitude apodization and causes a spot size increase in image space. The apodization in phase is called gap-induced aberration due to its dependence on the air gap. The gap-induced aberration does not come from lens surface imperfection, and it exhibits multiple orders of spherical aberration and astigmatism. The apodization in amplitude and phase is well characterized by separable supergaussian functions, where each function depends on the refractive index of the SIL n SIL and the air gap height h. The best defocus, based on characteristics of gap-induced aberration, is suggested to be a good compensator only for low nSIL and h. The system performance, as represented by Strehl ratio and spot width, is characterized as a function of nSIL and h before and after defocus. C vector formalism is developed based on the common-mode and different-mode transmission coefficients between p and s polarization. Experiments to confirm the apodization are summarized and compared with simulation.

A non-scanning imaging spectrometer simultaneously captures spatial and spectral information via multiple diffractive orders. Optics image a color scene in a field stop. A collimating lens converts the scene's spatial information into propagation angles. A diffractive disperser multiplexes the scene's spectral information into the propagation angles. A lens focused at infinity images multiple diffractive orders onto a large sensor array, which cannot distinguish the wavelength of incident light within the spectral bandpass of the instrument. The pixels of the sensor array collapse the two-spatial, one-spectral dimensions into a discrete, two-dimensional array. This collapsing of three dimensions into two is a mathematical projection. Computed tomography uses projections to reconstruct a three-dimensional object. Hence, this non-scanning imaging spectrometer has become known as the Computed-Tomography Imaging Spectrometer, or CTIS. The results imply nominal spatial and spectral resolution limits. When each projection is considered separately, the Nyquist spatial-sampling criterion provides a resolution limit. The limit cannot be achieved for an arbitrary scene. The highest spectral resolution can be obtained only if the highest spatial frequency is present. The formula that defines what each diffractive order measures is f(λ) ≈ nₓΔₓ fₓ+n(y)Δ(y)f(y) where f(λ) is a Fourier decomposition of the wavelength spectrum across the CTIS spectral bandwidth, fₓ and f(y) are the horizontal and vertical spatial frequencies, nₓ and n(y) are the diffractive-order numbers as would be obtained by crossed diffraction gratings, and Δₓ and Δ(y) are established by the optical design. Derived from a simple model of scalar diffraction, the formula is shown to be consistent with CTIS calibrations using a technique from computed tomography known as the Fourier-crosstalk matrix. The formula extends the definition of what CTIS projections measure to include cross-orders (nₓ and n(y) can both be non-zero) and anamorphic dispersion (Δₓ ≠ Δ(y)).

A phase-conjugate interferometric method of thin film analysis obtains three independent parameters with which to determine a film's refractive index n, absorption coefficient kappa, and thickness d. Because dimensionless intensity ratios are used, this method is self-calibrating except for light source polarization and incident angle. The use of self-pumped phase-conjugate reflectors makes the interferometer self-aligning and results in infinite spacing of fringes of equal thickness. A single layer thin film sample was analyzed by this technique, and the results compared to those of ellipsometry.

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The integration of modern electronic devices for information processing is rapidly ap-proaching an interconnect bottleneck. Silicon photonics can be a promising solution forcircumventing this bottleneck, as already being anticipated by many electronics manu-facturers including HP, IBM and Intel. In particular, optical interconnects can expeditedata transfer both between and within microchips. This thesis aims at two basic buildingblocks of silicon photonics: waveguides and resonators and addresses their applications inoptical signal processing and their potential integration with plasmonic devices. Firstly, the basic theories of waveguide and resonator are introduced. For a singleresonator which acts as a basic signal processing unit, the transmission, phase shift andgroup delay exhibit unique characteristics. Mode splitting is observed in both a singleresonator and a coupled-resonator system. By tuning the configuration of the coupled-resonator system, one can obtain different transmission characteristics for more advancedsignal processing. Secondly, the fabrication and characterization of silicon waveguides and resonatorsused in the thesis are introduced. The fabrication is carried out with e-beam lithographyfollowed by inductively coupled plasma etching. A vertical grating coupling method isadopted to characterize the transmission spectrum. Thirdly, based on a single-ring resonator, three kinds of signal processing are ex-perimentally demonstrated: (1) 10 Gb/s format conversion from non-return-to-zero toalternate-mark-inversion signal; (2) a microwave photonic phase shifter providing a tun-able phase shift of 0–4.6 rad for a 20 GHz signal; (3) a delay line providing maximaldelay times of 80 ps, 95 ps, 110 ps and 65 ps, respectively, for signals in return-to-zero,carrier-suppressed return-to-zero, return-to-zero duobinary, and return-to-zero alternate-mark-inversion formats. Fourthly, based on a single-ring resonator with mode-splitting, two kinds of signalprocessing are experimentally demonstrated: (1) a dense wavelength conversion using thefree carrier dispersion effect with a data rate ranging from 500 Mb/s to 5 Gb/s; (2) amaximum pulse advancement of 130 ps for a 1 ns signal pulse. Since silicon photonic devices are limited by diffraction limit, we further look intotheir hybridization with the diffraction-limit-free plasmonic devices. Two directional cou-plers from a Si photonic waveguide to a hybrid Si-metal plasmonic waveguide and to ametal-insulator-metal plasmonic waveguide are investigated. The proposed hybrid cou-plers feature a short coupling length, a high coupling efficiency, a high extinction ratioand a low insertion loss. / QC 20110315