This work investigates complete Mueller matrix polarization signatures in scattered light. A number of samples are studied using Mueller matrix imaging polarimetry, where samples are actively illuminated with a sequence of known polarization states. The capabilities of the Mueller matrix imaging polarimeter for scatter measurements are explored. Measuring polarization properties in scattered light from targets is important in remote sensing because polarization offers additional information unavailable from intensity measurements alone. Polarization helps discriminate surface features or material properties. The Mueller matrix contains detailed polarization and depolarization information possible for scattering objects, and every Mueller element conveys polarization coupling information. Polarization signatures are obtained at a number of different illumination and scatter angles, and a Mueller matrix bidirectional reflectance distribution function (MBRDF) in one dimension is used to compare various targets. Polarization metrics including diattenuation, retardance, and depolarization obtained from Mueller matrix data images provide methods for comparison, classification, and discrimination of targets. This work examines these reduced polarization parameters and how they vary as a function of scattering geometry, in order to determine which polarization signatures are the best discriminants for remote sensing or metrology. The Mueller matrix bidirectional reflectance distribution function, diattenuation, retardance, and depolarization properties are studied for a diverse group of manmade samples. A group of leaf samples is also studied, to see how natural samples behave and to compare natural and manmade samples. The most prevalent and useful discriminants for scattering samples appear in the depolarization data. Although this is not unexpected, these depolarization properties have not been studied in detail before and are not well described in the literature. Most depolarizing samples investigated showed an inverted Gaussian profile of depolarization magnitude versus scatter angle, with minimum depolarization for specular reflection which increases asymptotically as the scatter angle changes. Other patterns are found in the more noisy diattenuation and retardance data.

On the technical platform of hybrid organic-inorganic sol-gel, the integrated optoelectronics in the forms of heterogeneous integration between the hybrid sol-gel waveguide and the high refractive index semiconductors and the nonlinear functional doping of disperse red chromophore into hybrid sol-gel is developed. The structure of hybrid sol-gel waveguide on high index semiconductor substrate is designed with BPM-CAD software. A hybrid sol-gel based on MAPTMS and TEOS suitable for lower cladding for the waveguide is developed. The multi-layer hybrid sol-gel waveguide with good mode confinement and low polarization dependence is fabricated on Si and InP. As proof of concept, a 1 x 12 beam splitter based on multimode interference is fabricated on silicon substrate. The device shows excess loss below 0.65 dB and imbalance below 0.28 dB for both TE and TM polarization. A nonlinear active hybrid sol-gel doped with disperse red 13 has been developed by simple co-solvent method. It permits high loading concentration and has low optical loss at 1550 nm. The second-order nonlinear property of the active sol-gel is induced with corona poling and studied with second harmonic generation. A 3-fold of enhancement in the poling efficiency is achieved by blue light assisted corona poling. The chromophore alignment stability is improved by reducing the free volume of the formed inorganic network from the sol-gel condensation reaction. An active sol-gel channel waveguide has been fabricated using active and passive hybrid sol-gel materials by only photopatterning and spin-coating. An amplitude modulator based on the active sol-gel containing 30 wt.% of DR13 shows an electro-optic coefficient of 14 pm/V at 1550 nm and stable operation within the observation time of 24 days.

Short, high intensity laser pulses induce nonlinear optical effects in the atmosphere that have the potential to make them propagate for long distances. Applications for long distance propagation of short pulses include active spectral remote sensing and laser lightning control. Much of the work in this field has been done with infrared pulses; however, it has been proposed that ultraviolet pulses have the advantage that longer pulse lengths can be used, thereby delivering more energy. Long pulse lengths lead to a simplified instantaneous model for the plasma response, which has been shown by Schwarz and Diels to admit steady state or oscillatory solutions corresponding to beam propagation. We have verified this model and have adjusted it to achieve closer agreement with numerical results. In this work we investigate the effects of transient behavior, and the stability of these solutions. Analysis of the modulational instability is done from the plane wave level to a full three dimensional model of the propagation. It is shown that both the transient behavior arising from the finite pulse length, and the modulational instability cause pulses to fragment over lengths on the scale of meters. We present results showing the growth of unstable modes in various propagation regimes. We discuss the pertinent length scales for ultraviolet pulses, as well as the impact of the instability and transient effects on theory and experiment. The results imply that continuous-wave models are very limited when used to predict dynamical properties of pulse propagation.

Manufacturers of optical glass strive to make a product that is homogeneous, isotropic, and free of any bubbles or mechanical strain. Glass used in forming images is very good, but the process of mixing the constituent materials, and melting them into a glass is limited. The index of refraction varies based on the lack of uniformity remaining after the manufacturing process. Transmitted wavefronts will have errors due to this inhomogeneity. The most common method currently used to quantify the homogeneity of a glass sample is to measure in one direction through the glass. Variations along the test axis are integrated resulting in loss of positional information in this direction. Homogeneity is then reported by using the peak-to-valley wavefront error reducing the three dimensional nature of glass to a single value. Not only have we lost the longitudinal information, but we have also lost any knowledge of the transverse texture of the sample. We present in this research a method for retrieving three dimensional information about the inhomogeneity of a glass test piece. Computed tomography provides a well developed methodology for constructing a three dimensional measurement from two dimensional data. Common interferometric measurements, or projections, taken at multiple angles has sufficient information to estimate the full three dimensional structure of the test piece. Important differences from computed tomography used for medical diagnoses are explored. Refraction at the interfaces of the sample limits the number of angles over which projections can be made. The angular distance between projections also influences the accuracy of the reconstructed object.

Scanning Probe Microscopy (SPM) has been proven to be a powerful tool for imaging and lithography with nanometer resolution. The application of SPM to data storage may produce aerial storage densities far greater than what is currently available. As an effort in this direction, the properties of reversible transitions on the molecular scale in a complex of 3-nitrobenzal malononitrile and 1,4-phenylenediamine have been studied, by application of local electric field pulses from a SPM probe. Current pulses injection during the operation of a conducting-tip tapping-mode atomic force microscope has also been developed. Combination of these two techniques should be of importance for MEMS-based data storage. Another effort of ours is to develop an experimental configuration by combining the analytical power of Raman spectroscopy with the nanometer resolution of atomic force microscopy (AFM). Here, an AFM silicon nitride probe, coated with a 40 nm silver layer, was used to significantly enhance the Raman signal by laser excitation of surface plasmons in the tip coating. Experimental results indicate a local surface enhanced Raman scattering (SERS) increase of 105. Lateral scanning of the sample and collecting the SERS signal allows for a 2D image of the chemical identity of the probed sample simultaneous with its topography as measured by the AFM. Also, the ratio of Stokes to anti-Stokes can be used to obtain an absolute map of the local temperature across the sample.

Photonic devices fabricated by ion exchange in glass have evolved to the point where conventional assumptions of waveguide symmetry and mutual independence are no longer valid. For example, during field-assisted ion exchange processes, the nonhomogeneity of ionic conductivity in the vicinity of the waveguide results in a time-dependent perturbation of the electric field. Previous studies have shown that the depth and vertical symmetry of buried waveguides are noticeably affected by the field perturbation. This Dissertation describes an advanced modeling tool for guided-wave devices based on ion-exchanged glass waveguides. A genetic algorithm is proposed to determine the physical parameters that drive the ion exchange process. The diffusion equation describing binary ion exchange is solved numerically. The effect of field perturbation, due not only to the conductivity profile, but also to the proximity of adjacent waveguides or partial masking during a field-assisted burial, is accounted for. A semivectorial finite difference method is then employed to determine the modal properties of the waveguide structures. The model is validated by comparison with a fabricated waveguide containing a Bragg grating. The modeled waveguides are utilized in the design of a multimode interference (MMI) device. A novel genetic algorithm-based design methodology is developed to circumvent issues with the commonly used self-imaging theory that arise when the MMI device operates in the regime of weak guiding. A combination of semivectorial finite difference modeling in two transverse dimensions and mode propagation analysis (MPA) in the propagation direction is used to evaluate the merit of each trial design. Two examples are provided of a 1 x 4 power splitter, which show considerable improvement in power imbalance and polarization dependent loss over that obtained by self-imaging theory.

The writing and reading of 3 level run-length-limited (RLL) modulation signals on optical discs having active (recording) layers comprised of different phase change materials is discussed. These recordings represent a linear storage density enhancement of 50% Vs conventional (2-level) RLL modulation. Thermal simulations of the mark writing process provide a tool that can be used to optimize write strategies for ML-RLL recording.

The concept of in-vivo multi-spectral confocal microscopy is introduced. A slit-scanning multi-spectral confocal microendoscope (MCME) was built to demonstrate the technique. The MCME employs a flexible fiber-optic catheter coupled to a custom built slit-scan confocal microscope fitted with a custom built imaging spectrometer. The catheter consists of a fiber-optic imaging bundle linked to a miniature objective and focus assembly. The design and performance of the miniature objective and focus assembly are discussed. The 3mm diameter catheter may be used on its own or routed though the instrument channel of a commercial endoscope. The confocal nature of the system provides optical sectioning with 3μm lateral resolution and 30mum axial resolution. The prism based multi-spectral detection assembly is typically configured to collect 30 spectral samples over the visible chromatic range. The spectral sampling rate varies from 4nm/pixel at 490nm to 8nm/pixel at 660nm and the minimum resolvable wavelength difference varies from 7nm to 18nm over the same spectral range. Each of these characteristics are primarily dictated by the dispersive power of the prism. The MCME is designed to examine cellular structures during optical biopsy and to exploit the diagnostic information contained within the spectral domain. The primary applications for the system include diagnosis of disease in the gastro-intestinal tract and female reproductive system. Recent data from the grayscale imaging mode are presented. Preliminary multi-spectral results from phantoms, cell cultures, and excised human tissue are presented to demonstrate the potential of in-vivo multi-spectral imaging.

To study propagation in bent waveguides numerically the most common technique used is the Beam Propagation Method (BPM), with either the split-step procedure and Fast Fourier Transform algorithm, or a finite difference approach. Most versions are based on a first order modification of the permittivity profile for scalar or full vector wave equations. Others are based on a longitudinally variant index profile and wide angle beam propagation techniques. New device applications are well beyond the limitations of the present numerical approaches. An example of these applications are polymer and semiconductor ring lasers, (de)multiplexing systems, and polarization converters based on bent waveguides. They will require more accurate and novel numerical approaches to solve more complex problems at smaller radii. Important issues are characteristics such as: the modal spectra, total loss and loss rates, and modal field distributions.

This dissertation investigates the nonlinear optics of circular-grating distributed-feedback (CGDFB) semiconductor lasers. Included are gain saturation, index saturation, and self- and cross-phase modulation third-order nonlinearities. After a brief review of the historical and technical background needed to understand our results, a numerical model is developed for gain saturation. This model includes a radially-varying nonlinear gain and a uniformly-distributed grating loss in the solution of the coupled-mode equations. The results show that lossy, high-power operation results in an optimum coupling strength for efficient conversion of pump power into useful output pourer. Results also show a multi-mode spectrum for large coupling strengths, a consequence of mode selection governed by a spatially-varying gain distribution. Single-mode selection entails operating at approximately the optimum coupling coefficient determined for efficient pumping. These results are extended by including the gain/index coupling described by the linewidth enhancement factor. A unique feature of this coupling is the possibility of above-threshold, single-mode operation over a limited power range, even for the case of large coupling coefficients. Similar results are obtained for the circular-grating distributed-Bragg-reflector (CGDBR) laser. The excess spontaneous emission rate associated with the nonuniform CGDFB radial (longitudinal) field profiles is also calculated. The resulting above-threshold linewidth closely follows the inverse-power dependence predicted by the Schawlow-Townes relation. To include third-order nonlinearities, we derive coupled-mode equations which describe self- and cross-phase modulation effects via an intensity-dependent refractive index. It is then shown that the circular-grating structure acts as an all-optical switch. We also find that an additional pi/2 phase shift at the center of the grating permits the possibility of self-pulsing cylindrical gap solitons. For a positive nonlinearity (n2 it is shown numerically that these solitons are not physically allowable. That is, for a passive structure, time-dependent self-pulsing behavior is damped by the 1/beta r factor in the self- and cross-phase modulation terms. This damping can be compensated for by the addition of gain. In this case, self-pulsing with an excellent contrast ratio is obtained. The numerical methods used to obtain both steady-state and time-dependent solutions are also described. The steady-state results are obtained using a multi-dimensional Newton-Raphson technique known as the "shooting" method. Time-dependent data use a fourth-order predictor-corrector technique. The stability of the time-dependent solutions to the exact coupled-mode equations is reviewed. Coupled-mode equations based on a large-radius approximation for the Hankel functions are found to be stable over a wider range of variables. Numerical tests used to verify the time-dependent software are described.