This thesis investigates the feasibility of employing an optical imaging system for the application of in vivo flow cytometry for detecting rare circulating tumor cells (CTCs) in vasculature. This investigation presented used three optical imaging configurations: a Nikon Eclipse E600 fluorescence microscope with a PIXIS 2048B CCD camera; a Nikon Eclipse E600 fluorescence microscope with a ThorLabs DCC 3240N CMOS camera; and a custom built confocal microendoscope with a ThorLabs DCC 3240N CMOS camera. These systems were employed to gain insight as to what signal to noise ratios and sensitivities are required to sufficiently detect fluorescently labeled cancer cells. This work presents general concepts of fluorescence and confocal microscopy, the experimental setups employed, and experimental measurements and results obtained. The experimental measurements involved the following: the simulation of flow cytometry by imaging green fluorescent microspheres, with a fluorescence excitation range of 505-515 nm and a diameter of 15µm, in a square crit tube moving on a translational stage, and imaging a selection of cells that included MCF10A breast cells (non-cancerous), OVCAR3 ovarian cancer cells, and patient derived xenogram (PDX) breast cancer cells, which express folate-receptor proteins on their surface. We fluorescently labeled these cells with the introduction of a new folate-receptor targeted fluorescent contrast agent OTL38, made by On Target Laboratories. The results established that we were able to image and detect fluorescence microspheres with a minimum signal to noise ratio (SNR) of 2.3 using the ThorLabs DCC 3240N camera on the Nikon Fluorescence microscope. We were able to image and detect the cells used on all three system configurations. Analyzing the different cell uptake efficacies of the contrast agent OTL38, we established that the SNR levels were variable when imaging PDX breast cancer cells. We propose future work to investigate possible effects on the variability of SNR results, as well as, and future steps in designing a real-time optical fluorescence imaging system for in vivo flow cytometry.

The goal of this dissertation research is to develop and demonstrate a functioning snapshot imaging spectropolarimeter for the long wavelength infrared region of the electromagnetic spectrum (wavelengths from 8-12 microns). Such an optical system will be able to simultaneously measure both the spectral and polarimetric signatures of all the spatial locations/targets in a scene with just a single integration period of a camera. This will be accomplished by combining the use of computed tomographic imaging spectrometry (CTIS) and channeled spectropolarimetry. The proposed system will be the first instrument of this type specifically designed to operate in the long wavelength infrared region, as well as being the first demonstration of such a system using an uncooled infrared focal plane array. In addition to the design and construction of the proof-of-concept snapshot imaging spectropolarimeter LWIR system, the dissertation research will also focus on a variety of methods on improving CTIS system performance. These enhancements will include some newly proposed methods of system design, calibration, and reconstruction aimed at improving the speed of reconstructions allowing for the first demonstration of a CTIS system capable of computing reconstructions in 'real time.'

Nano-structures, such as photonic crystal cavities and metallic antennas, allow one to focus and store optical energy into very small volumes, greatly increasing light-matter interactions. These structures produce resonances which are typically characterized by how well they confine energy both temporally (quality factor–Q) and spatially (mode volume–V). In order to observe non-linear effects, modified spontaneous emission (e.g. Purcell enhancement), or quantum effects (e.g. vacuum Rabi splitting), one needs to maximize the ratio of Q/V while also maximizing the coupling between the resonance and the active medium. In this dissertation I will discuss several projects related by the goal of controlling light-matter interactions using such nano-structures. In the first portion of this dissertation I will discuss the deterministic placement of self-assembled InAs quantum dots, which would allow one to precisely position an optically-active material, for maximum interaction, inside of a photonic crystal cavity. Additionally, I will discuss the use of atomic layer deposition to tune and improve both the resonance wavelength and quality factor of silicon based photonic crystal cavities. Moving from dielectric materials to metals allows one to achieve mode-volumes well below the diffraction limit. The quality factor of these resonators is severely limited by Ohmic loss in the metal; however, the small mode-volume still allows for greatly enhanced light-matter interaction. In the second portion of this dissertation I will investigate the coupling between an array of metallic resonators (antennas) and a nearby semiconductor quantum well. Using time-resolved pump-probe measurements I study the properties of the coupled system and compare the results to a model which allows one to quantitatively compare various antenna geometries.

This work presents the recent advances in photorefractive polymers for use in updatable holographic displays. A model with which to predict the effect of coplanar electrode geometry on diffraction uniformity in photorefractive (PR) polymer display devices was developed. Assumptions made in the standard use cases with constant electric field throughout the bulk of the media are no longer valid in the regions of extreme electric fields present in this type of device. Using electric field induced second harmonic generation (EFISHG) observed with multiphoton microscopy, the physical response in regions of internal electric fields which fall outside the standard regimes of validity were probed. Adjustments to the standard model were made, and the results of the new model were corroborated by holographic four-wave mixing measurements. The recent development of a single mode fiber-based pulsed laser with variable pulse length, energy, and repetition rate has enabled the characterization of photorefractive devices in a previously inaccessible regime located between millisecond and nanosecond pulse recording. A pulse width range of nine orders of magnitude opens the door to device and supporting laser optimization for use in video-rate holographic display. Device optimization has resulted in 5x improvement in single pulse four-wave mixing diffraction efficiencies to 10 - 11.5 % at pulse widths ranging between 6 ns and 100 µs. The grating recording time was likewise reduced by 5x to 16 ms at an applied bias of 72.5 V/μm. These improvements support 30 Hz update rates, which combined with the 3.3 - 10 kHz repetition rate pulsed laser, pave the way for real-time updatable holographic display.

In this dissertation I present theory and experimental results obtained in the Jones research group at the University of Arizona investigating the feasibility of neutral Hg as a candidate for an atomic clock. This investigation includes laser-cooling and trapping of several neutral Hg isotopes as well as spectroscopy of the 6¹S₀ - 6³P₀ doubly forbidden clock transition in neutral Hg¹⁹⁹. We demonstrate precision spectroscopy of the ground state cooling/trapping transition of neutral mercury at 254 nm using an optically pumped semiconductor laser (OPSL). This demonstration exhibits the utility of optically pumped semiconductor lasers (OPSLs) in the field of precision atomic spectroscopy. The OPSL lases at 1015 nm and is frequency quadrupled to provide the trapping light for the ground state cooling transition. We get up to 1.5 W single-frequency output power having a linewidth of < 10 kHz in the IR with active feedback. We frequency quadruple the OPSL in two external cavity stages to produce up to 120 mW of deep-UV light at 253.7 nm. I give a detailed characterization of the construction and implementation of the neutral Hg vapor cell magneto-optical trap (MOT). The trap can be loaded in as quickly as 75 ms at background vapor pressures below 10⁻⁸ torr. At reduced background pressure (< 10⁻¹⁰ torr) the loading time approaches 2 sec. We describe construction and stabilization of a laser resonant with the Hg¹⁹⁹ clock transition and the methods employed to find and perform the experimentally delicate spectroscopy of the clock transition. We present experimental results and analysis for our initial spectroscopy of the 6¹S₀- 6³P₀ clock transition in the Hg¹⁹⁹ isotope of neutral mercury.

Sensing in scattering environments, such as fog and dust, poses a serious challenge for all optical systems and is important for many critical surveillance applications. The use of polarized light, specifically circularly polarized light, has shown great promise for improving detection range and sensing in highly scattering, real-world environments. While the potential impact to application is significant, the optical science and sensing community lacks data on broad wavelength and environmental parameters where circularly polarized light outperforms linearly polarized light, increasing detection range and signal persistence. In this dissertation I quantify, through simulation and experimental results, the advantage of circularly polarized light in laboratory and real-world scattering environments - focusing on circularly polarized light's superior persistence in these environments. I present new and unique contributions to the study of polarized light in both isotropic (Rayleigh regime) and forward-scattering environments, showing circular polarization's superior persistence increases detection range for real-world environments over broad wavelength and particle size regimes. Utilizing polarization-tracking Monte Carlo simulations for varying particle size, wavelength, and refractive index, I quantify when circular polarization outperforms linear polarization in maintaining the illuminating polarization state for large optical thicknesses, persisting to longer ranges. I identify many real-world environments with particle sizes of radiation fog, advection fog, and Sahara dust where circular polarization outperforms linear polarization over broad wavelength ranges in the infrared spectrum. This enhancement with circular polarization can be exploited to improve sensing range and target detection in obscurant environments that are important in many critical surveillance applications. Conversely, I also identify a few environmental configurations where linear polarization outperforms circular polarization. However, circular polarization's response is generally larger and over broader wavelength ranges in the infrared regime for real-world scattering environments. Experiments were conducted for both 1) isotopically-scattering (Rayleigh regime) environments and 2) forward-scattering environments using polystyrene microspheres with well-defined diameters. These measurements demonstrated that in the forward-scattering environments, circular polarization persists through increasing optical thickness better than linear polarization. Variations in persistence were investigated as a function of collection geometry, angular field of view, and collection area. Persistence for both linear and circular polarization was found to be more susceptible to collection geometry, specifically increased collection area, in the isotropically-scattering (Rayleigh regime) environment. Similarly, linear polarization in the forward-scattering environments is dependent upon changes in collection geometry. Significantly, circular polarization's response is nearly unaffected by variations of both field of view and collection area for the forward-scattering environments. Circular polarization proves to be not only generally better in persistence but also more tolerant of variations in angular collection and collection area compared to linear polarization, making it ideal and flexible for use in optical sensing systems in scattering environments. Finally, I present simulation results that show the evolution of linear and circularly polarized light as it scatters throughout both isotropic (Rayleigh regime) and forward-scattering environments as a function of scattering event. Circularly polarized light persists through a larger number of scattering events longer than linearly polarized light for all forward-scattering environments; but not for scattering in the Rayleigh regime. Circular polarization's increased persistence occurs for both forward and backscattered light. The evolution of the polarization states as they propagate through the various environments are illustrated on the Poincaré sphere after successive scattering events. This work displays individual scattering events as well as a cumulative, measureable result, in an intuitive manner. Throughout this dissertation I quantify the polarization persistence and memory of circularly polarized light in real-world scattering environments over broad wavelength, particle size, and collection-geometry parameter spaces; and for the first time, detail the evolution and modification of both circularly and linearly polarized states through isotropic and forward-scattering environments. These results show how circular polarization can extend range and sensing capability in surveillance sensing applications in real-world scattering environments.

Notwithstanding several years of robust growth, solar energy still only accounts for<1% of total electrical generation in the US. Before solar energy can substantially replace fossil fuels subsidy-free at utility scale, further cost reductions and efficiency improvements are needed in complete generating systems. Flat panel silicon PV modules are by far the most dominant solar technology today, but have little room for improvement in efficiency and are limited by balance of system costs. Concentrated PV (CPV) is an alternate approach with long-term potential for much higher efficiency in sunny climates. In CPV modules, large area optics collect and concentrate direct sunlight onto small multi-junction cells with>40% conversion efficiency. Concentrated Solar Power (CSP) uses mirrors to concentrate sunlight onto thermally absorbing receivers, which generate electricity with convention thermal cycles. In this dissertation, four new optical approaches to CPV and CSP with potential for lower cost are analyzed. Common to each approach is the use of large square glass reflectors, which have very low areal cost (~$35/m^2) and field-proven reliability in the CSP industry. Chapter 2 describes a freeform toroidal lens array used to intercept the low concentration line focus of a parabolic trough to produce multiple high concentration foci (>800X) for multi-junction cells. In Chapter 3, three embodiments of dish mirrors and freeform lenslet arrays are explored, including an off-axis system. In each case, a dish mirror illuminates a freeform lenslet array, which divides sunlight equally to a sparse matrix of multi-junction cells. The off-axis optical system achieves +/-0.45° acceptance angle and averages 1215X geometric concentration over 400 multi-junction cells. Chapter 4 proposes a new architecture for CSP central receivers that achieves extremely high collection efficiency (>70%) with unconventional heliostat field tracking. In Chapter 5, the design and preliminary testing of a spectrum-splitting hybrid PV/thermal generator is discussed. This system has the advantage of 'drop-in' capability in existing CSP trough plants and allows for thermal storage, an important mitigation to the intermittency of the solar resource.

The development of high average and peak power ultrashort pulsed fiber lasers is important for many critical research, industrial, and defense applications. However, the performance of mode-locked fiber oscillators still lags behind that of solid-state counterparts such as Kerr-lens mode-locked Ti:sapphire lasers. Despite the drawbacks in cost, size and required maintenance, Ti:sapphire remains the workhorse of ultrafast science. One of the remaining challenges for fiber lasers to overcome is their limited set of accessible wavelengths. Unfortunately, readily available ytterbium, erbium and thulium fiber lasers can produce coherent radiation only near 1, 1.55 and 2μm, respectively. There remain a significant number of wavelength regions that fiber lasers cannot address. In this thesis, novel fiber lasers producing ultrashort pulses at wavelengths not currently accessible with established active rare-earth-doped fibers are investigated. Our main approach is to use various nonlinear optical effects to generate new laser wavelengths. First, a watt-level synchronously pumped Raman fiber oscillator generating tens of nanojoules femtosecond pulses is demonstrated. Stimulated Raman scattering in a passive fiber within an oscillator cavity allows formation of Raman pulses that are spectrally redshifted with respect to the pump pulses. World-record output pulse energy and conversion efficiency have been achieved with our femtosecond Raman fiber laser design. We have also demonstrated a high power, widely tunable all-fiber optical parametric oscillator (FOPO) based on four-wave mixing in a passive fiber. The FOPO is synchronously pumped with an Yb³⁺-doped mode-locked fiber laser working at ~1040nm. The FOPO produces ultrashort pulses tunable from 760 to 1560nm. Record pulse energy is generated at the output of the femtosecond FOPO. Depending on the configuration of the FOPO, the duration of produced pulses varies between 170fs and 3ps. This new laser source has similar performance to standard Ti:sa femtosecond lasers so it can potentially replace the latter in many applications. Ultrashort optical pulses in the mid-IR and long-IR range (2-20 μm) have many important applications in gas sensing, counter-measures, etc. The realization of the ultrashort pulses in the mid-IR and long-IR wavelengths requires the use of free-space nonlinear crystals. An efficient mid-IR source based on difference frequency generation (DFG) in an AgGaS₂ crystal using femtosecond erbium/thulium pump fiber laser has been proposed and demonstrated. The photon conversion efficiency of the pump wave (1.55μm) to idler wave (9.2μm) has been measured to be 16%, which is today a record for conversion of near-IR light radiation from fiber lasers to 9μm spectral range. Potentially the photon conversion efficiency can be increased up to 60% by using pump pulses having higher peak power. Finally, generation of supercontinuum (SC) light in the mid-IR spectral range is also demonstrated. It is well known that SC produced in standard optical fibers is limited to ~6μm by material absorption. The liquid core optical fiber platform has been proposed to address this matter. Several highly nonlinear liquids have minimal absorption in the mid-IR wavelength range, which potentially allows us to create broadband SC light in this spectral region. SC generation up to 2.4μm in an integrated hollow core optical fiber filled with CS₂ has been demonstrated. Further development of the liquid core optical fiber platform should allow generation of the SC covering wavelengths beyond 6μm.

Adaptive optics (AO) systems have become an essential part of ground-based telescopes and enable diffraction-limited imaging at near-IR and mid-IR wavelengths. For several key science applications the required wavefront quality is higher than what current systems can deliver. For instance obtaining high quality diffraction-limited images at visible wavelengths requires residual wavefront errors to be well below 100 nm RMS. High contrast imaging of exoplanets and disks around nearby stars requires high accuracy control of low-order modes that dominate atmospheric turbulence and scatter light at small angles where exoplanets are likely to be found. Imaging planets using a high contrast corona graphic camera, as is the case for the Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) on the Very Large Telescope (VLT), and the Gemini Planet Imager (GPI), requires even greater wavefront control accuracy. My dissertation develops a highly sensitive non-linear Curvature Wavefront Sensor (nlCWFS) that can deliver diffraction-limited (λ/D) images, in the visible, by approaching the theoretical sensitivity limit imposed by fundamental physics. The nlCWFS is derived from the successful curvature wavefront sensing concept but uses a non-linear reconstructor in order to maintain sensitivity to low spatial frequencies. The nlCWFS sensitivity makes it optimal for extreme AO and visible AO systems because it utilizes the full spatial coherence of the pupil plane as opposed to conventional sensors such as the Shack-Hartmann Wavefront Sensor (SHWFS) which operate at the atmospheric seeing limit (λ/r₀). The difference is equivalent to a gain of (D/r₀)² in sensitivity, for the lowest order mode, which translates to the nlCWFS requiring that many fewer photons. When background limited the nlCWFS sensitivity scales as D⁴, a combination of D² gain due to the diffraction limit and D² gain due to telescope's collecting power. Whereas conventional wavefront sensors only benefit from the D² gain due to the telescope's collecting power. For a 6.5 m telescope, at 0.5 μm, and seeing of 0.5", the nlCWFS can deliver for low order modes the same wavefront measurement accuracy as the SHWFS with 1000 times fewer photons. This is especially significant for upcoming extremely large telescopes such as the Giant Magellan Telescope (GMT) which has a 25.4 m aperture, the Thirty Meter Telescope (TMT) and the European Extremely Large Telescope (E-ELT) which has a 39 m aperture.

Coated nanoparticles (CNP) are core-shell particles consisting of differing layers of epsilon positive (EP) and epsilon negative (ENG) materials. The juxtaposition of these EP and ENG materials can lead to the possibility of coupling incident plane waves to surface plasmon resonances (SPR) for particles even highly subwavelength in size. We introduce standard models of the permittivities of the noble metals used in these CNPs, and propose corrections to them based on experimental data when their sizes are extremely small. Mie theory is the solution to plane wave scattering by spheres and we extend the solution here to spheres consisting of an arbitrary number of layers. We discuss the resonance behaviors of passive CNPs with an emphasis on how the Coated nanoparticles (CNP) are core-shell particles consisting of differing layers of epsilon positive (EP) and epsilon negative (ENG) materials. The juxtaposition of these EP and ENG materials can lead to the possibility of coupling incident plane waves to surface plasmon resonances (SPR) for particles even highly subwavelength in size. We introduce standard models of the permittivities of the noble metals used in these CNPs, and propose corrections to them based on experimental data when their sizes are extremely small. Mie theory is the solution to plane wave scattering by spheres and we extend the solution here to spheres consisting of an arbitrary number of layers. We discuss the resonance behaviors of passive CNPs with an emphasis on how the resonance wavelength can be tuned by controlling the material properties and radii of the various layers in the configuration. It is demonstrated that these passive CNPs have scattering cross sections much larger than their geometrical size, but their resonance strengths are attenuated because of the inherent losses in the metals. To overcome this limitation, we show how the introduction of active material into the CNPs can not only overcome these losses, but can actually lead to an amplification of the scattering of the incident field. We report several optimized active CNP designs, including ones based on quantum dot gain media and study their performance characteristics with particular attention to the effect of the location of the gain material on the performance of these designs. We investigate the ability to control the scattered field directivity of the CNPs in both their far- and near-field regions and propose designs with minimal backscattering and those emulating macroscopic nanojets. We compare data generated by initial efforts to experimentally prepare CNPs and compare against analytical and numerical simulation results. Finally, we suggest a variety of interesting future research directions. resonance wavelength can be tuned by controlling the material properties and radii of the various layers in the configuration. It is demonstrated that these passive CNPs have scattering cross sections much larger than their geometrical size, but their resonance strengths are attenuated because of the inherent losses in the metals. To overcome this limitation, we show how the introduction of active material into the CNPs can not only overcome these losses, but can actually lead to an amplification of the scattering of the incident field. We report several optimized active CNP designs, including ones based on quantum dot gain media and study their performance characteristics with particular attention to the effect of the location of the gain material on the performance of these designs. We investigate the ability to control the scattered field directivity of the CNPs in both their far- and near-field regions and propose designs with minimal backscattering and those emulating macroscopic nanojets. We compare data generated by initial efforts to experimentally prepare CNPs and compare against analytical and numerical simulation results. Finally, we suggest a variety of interesting future research directions