Ellipsometry techniques look at changes in polarization states to measure optical properties of thin film materials. A beam reflected from a substrate measures the real and imaginary parts of the index of the material represented as n and k, respectively. Measuring the substrate at several angles gives additional information that can be used to measure multilayer thin film stacks. However, the outstanding problem in standard ellipsometry is that it uses a limited number of incident polarization states (s and p). This limits the technique to isotropic materials. The technique discussed in this paper extends the standard process to measure anisotropic materials by using a larger set of incident polarization states. By using a polarimeter to generate several incident polarization states and measure the polarization properties of the sample, ellipsometry can be performed on biaxial materials.Use of an optimization algorithm in conjunction with biaxial ellipsometry can more accurately determine the dielectric tensor of individual layers in multilayer structures. Biaxial ellipsometry is a technique that measures the dielectric tensors of a biaxial substrate, single-layer thin film, or multi-layer structure. The dielectric tensor of a biaxial material consists of the real and imaginary parts of the three orthogonal principal indices (nₓ + ikₓ, n(y) +ik(y) and n(z) + ik(z)) as well as three Euler angles (α, β, and γ) to describe its orientation. The method utilized in this work measures an angle-of-incidence Mueller matrix from a Mueller matrix imaging polarimeter equipped with a pair of microscope objectives that have low polarization properties. To accurately determine the dielectric tensors for multilayer samples, the angle-of-incidence Mueller matrix images are collected for multiple wavelengths. This is done in either a transmission mode or a reflection mode, each incorporates an appropriate dispersion model. Given approximate a priori knowledge of the dielectric tensor and film thickness, a Jones reflectivity matrix is calculated by solving Maxwell's equations at each surface. Converting the Jones matrix into a Mueller matrix provides a starting point for optimization. An optimization algorithm then finds the best fit dielectric tensor based on the measured angle-of-incidence Mueller matrix image. This process can be applied to polarizing materials, birefringent crystals and the multilayer structures of liquid crystal displays. In particular, the need for such accuracy in liquid crystal displays is growing as their applications in industry evolve.

We have investigated ways of modifying a common water soluble CdTe NCs to become non-photobleaching. Such NCs are capable of responding reversibly to an inter-switching of the oxygen and argon environments over multiple hours of photoexcitation. They are found to quench upon exposure to oxygen, but when the system is purged with argon, their photoluminescence (PL) revives to the original intensity. Such discovery could potentially be used as oxygen nanosensors. These PL robust CdTe NCs immobilized on glass substrates also exhibit significant changes in their PL when certain organic/bio molecules are placed in their vicinity (nanoscale). This novel technique also known as NC-organic molecule close proximity imaging (NC-cp imaging) has found to provide contrast ratio greater by a factor of 2-3 compared to conventional fluorescence imaging technique. PL of NCs is recoverable upon removal of these organic molecules, therefore validating these NCs as potential all-optical organic molecular nanosensors and, upon optimization, ultimately serving as point detectors for purposes of super-resolution microscopy (with proper instrumentation). No solvents are required for this sensing mechanism since all solutions were dried under argon flow. Furthermore, core graded shell CdSe/CdSeₓS(1-x)/CdS giant nanocrystal (g-NCs) were found to have very robust PL temperature response. At a size of 10.2 nm in diameter, these g-NCs undergo PL drop of only 30% at 355K (normalized to PL intensity at 85K). In comparison, the core step shells CdSe/CdS g-NCs at the same diameter exhibit 80% PL drop at 355K. Spectral shifting and broadening were acquired and found to be 5-10 times and 2-4 times smaller respectively than the standard CdSe core and CdSe/CdS core shell NCs. It is also discovered that these core graded shell g-NCs are largely nonblinking and have insignificant photoluminescence decay even after exciting the samples at very high irradiance (44 kW/cm²) for over an hour. These types of g-NCs have great potential to be used as the active medium for temperature insensitive laser devices in the visible range or temperature insensitive bioprobes for bioimaging applications.

Deflectometry is a powerful metrology technique that uses off-the-shelf equipment to achieve nm-level accuracy measurement. This process is typically made by scanning lines of pixels or encoding the surface slopes information with phase using sinusoidal waves. Various measurement techniques exist, centroiding and phase-shifting being the most accepted, but their sensitivities vary with experimental conditions. We demonstrate solutions based on various parameters such as uncertainty or efficiency. The results are presented in a decision matrix and merit function. The parameters can be varied to represent various conditions. In particular, we are interested in using deflectometry in a context of fast, affordable and robust. Since none of the existing methods perform well under those parameters, we introduce a new method using binary patterns. Binary Pattern Deflectometry allows almost instant, simple and accurate slope retrieval, which is required for applications using mobile devices. We detail the theory of this new deflectometry method and the challenges of its implementation. Furthermore, the binary pattern method can also be combined with a classic phase-shifting method to eliminate the need of a complex unwrapping algorithm and retrieve the absolute phase, especially in cases like segmented optics where spatial algorithms have difficulties. Finally, whether it is used as a standalone or combined with phase-shifting, the binary patterns can, within seconds, calculate the slopes of any specular reflective surface. However there is no portable device to quickly measure eyeglasses, lenses, or mirrors. To complete the study, we present an entirely portable new deflectometry technique that runs on any Android™ smartphone with a front-facing camera. Our technique overcomes some specific issues of portable devices, like screen non-linearity or automatic gain control (AGC). We demonstrate our application by measuring an amateur telescope mirror and simulating the faulty Hubble Space Telescope primary mirror. In both cases, the application found the same amount of aberrations that were measured with an interferometer. Our technique can, in less than a minute, measure the sag errors of curved surfaces smaller than 50 nm RMS, simply using a smartphone.

The development of a quantitative phase microscope (QPM) has allowed the ability to acquire real-time phase movies of biological processes. The image processing of the data is critical to the system's ability to measure relative changes. The phase data must be consistent throughout a measurement and background fluctuations must be minimized. The research presented in this work discusses methods to effectively process sequences of phase data such that it can be used to quantify changes within real-time studies of living cells. This work begins by exploring two-dimensional phase unwrapping to determine the most effective ways to estimate the measured phase surface. Conventional methods of comparing unwrapping performance will be used. In addition, a novel method will be introduced that can characterize accuracy using continuity of derivatives. It will be shown that the most accurate phase estimates are made using modulation data with quality-guided phase unwrapping. After two-dimensionally unwrapping all frames of data within a measurement, there are background fluctuations due to residual surface shape as well as mean phase value fluctuations. Traditionally, manual background removal methods are implemented. Due to the large streams of data that need to be analyzed for the QPM, an automated background removal method is introduced that automatically discriminates the background from features of interest and characterizes and removes the background shape from all frames within a sequence of data. No user intervention is required and the performance rivals manual methods. The final step in processing data from a QPM is to ensure consistent phase unwrapping over an entire dataset. This is a previously undiscussed topic within the field of quantitative phase microscopy. The two-dimensional phase unwrapping methods result in reasonable phase estimates of the measured sample however there are often inconsistencies in local regions amongst sequential frames of data. This work introduces a new method, Smart Temporal unwrapping that minimizes temporal inconsistencies. The image processing methods presented in this work combine to allow phase data acquired using a QPM to quantify relative changes in biological samples. These processing steps effectively minimize errors due to system vibration, residual measurement aberration, and phase unwrapping inconsistencies.

The ability to create arbitrary patterned linear, circular, and elliptical liquid crystal polymer polarizers is demonstrated in this work. The operating wavelength of the thin-film polarizer ranges from 400 to 4200 nm. The linear absorption-based micropolarizer is fabricated using dichroic dye as a guest in liquid crystal polymer host with feature sizes as small as 4 µm. The circular interference-based micropolarizer is fabricated using cholesteric liquid crystal polymers with feature sizes as small as 6.2 µm. The elliptical micropolarizer is achieved using the combination of a microretarder and a micropolarizer. The chemistry, fabrication process, spatial resolution and optical properties of micropolarizers are presented. Alignments of liquid crystal polymers and cholesteric liquid crystal polymers are both achieved using photoalignment technique with polarized photo-lithography. Two different methods, thermal annealing and solvent rinse, are utilized for patterning cholesteric liquid crystal polymers over large areas. In addition to exploring absorption-based and interference-based micropolarizers, arrays of micropolarizers are fabricated for the construction of 580nm and 760nm division-of-focal-plane full-Stokes imaging polarimeters. The polarimeter utilizes a set of four optimized measurements which represent a regular tetrahedron inscribed in the Poincaré sphere. Results from the device fabrication, instrument calibration and characterization for the 580 nm polarimeter are presented. The optimized imaging polarimeter can be used for sampling the polarization signature across a scene with a resolution of 1608 x 1208 x 14-bit at 20 frames/second.

Sol-gel materials are an important material class, as they provide for easy modification of material properties, good processability and routine synthesis. This allows for the tailoring of the material properties to the needs of specific device designs. In the case of electro-optic modulators with a coplanar or coplanar strip (CPS) electrode design, sol-gel cladding materials can be used to confine the light to the electro-optic material as well as to concentrate the electrical field used for poling and driving the modulator. Another important material property that can influence the poling efficiency is the conductivity of the material surrounding the electro-optic material, and this property can also be controlled. In this dissertation I discuss several approaches to altering the material properties of sol-gel materials in order to achieve a specific performance objective. The optical loss in the telecom regime as well the refractive index will be discussed. I will introduce a novel titania-based family of sol-gel materials, which exhibit very high refractive indices, tuneability and high dielectric constant (ε). Coplanar electrode design is useful for device platforms that do not allow for a microstrip geometry, such as silicon and Si₃N₄ devices. CPS electrodes however bring new challenges with them, especially optimizing the poling process. I will discuss a method for characterizing coplanar poled polymer films by a modified Teng-Man technique as well as with second harmonic microscope (SHM). SHM allows for an almost real-time mapping of the Pockels coefficient. The described method allows for quantitative measurements of the Pockels coefficient in a poled film with spatial resolution at the micron level. Finally, I will discuss the device design considerations for a silicon-EO hybrid modulator. Optimal dimensions for the silicon waveguide are shown and the feasibility of the proposed electrode design for high speed operation is theoretically shown. All design parameters, including electrode spacing and height are optimized towards the highest possible figure of merit. The functionality of a simple test device is shown. For Si₃N₄ waveguides optimal dimensions are found as well and the influence of a high ε sol-gel side cladding is examined.

A process to design a relay lens is presented. The process is to concatenate a collimator lens and an imaging lens. For this study the imager and collimator are required to have an external or remote stop in collimated space to prevent interference upon concatenation. The relay is created by concatenating the collimator and imager at the external or remote stop. This process allows the use of optimized infinite conjugate imagers to develop a relay lens. A collimator lens can be created by reversing the path of an imager. Magnification is achieved by scaling the focal length of the imager while keeping the focal length of the collimator constant. Computer design software is used to develop examples of relays designed using the process. A discussion of the aberration theory governing the integration of the collimator and imager to create a relay is also presented.

In this thesis, several novel devices for fiber laser are proposed and demonstrated. The first type of device is based on modal interference in non-adiabatic fiber tapers. Using such tapers, we demonstrate a simple technique to tune the wavelength of an all-fiber erbium-doped laser. Next, we systematically investigate the use of non-adiabatic fiber tapers for sensing purposes. As a result of this investigation, we have built and characterized several simple and sensitive sensors for highly accurate measurements of strain, temperature, and refractive index.Another class of devices investigated in this dissertation is based on micro-cavities. We propose and demonstrate, for the first time, the use of high-Q micro-spherical resonators as feedback mirrors for fiber lasers. The advantages of these new "mirrors" include compactness, low cost, tunability of the reflection coefficient, and an extremely narrow reflection bandwidth.We demonstrate single-frequency and Q-switched fiber lasers based on micro-spherical mirrors. The next natural step in the development of fiber-lasers involves the phenomenon of mode-locking. For this purpose, we developed a novel type of saturable absorber based on a fiber-taper embedded in a carbon nanotube/polymer composite material (FTECntPC). Subsequently, mode-locking was successfully demonstrated in an erbium-doped fiber laser using the aforementioned FTECntPC saturable absorber. We have thoroughly investigated the dynamics of passively mode-locked fiber lasers that incorporate the FTECntPC saturable absorber. With this new saturable absorber we have been able to obtain the highest pulse energies that have been generated to date directly from a soliton all-fiber laser. In addition, with the help of the novel saturable absorber, we have been able to build and analyze the first bi-directional passively mode-locked fiber laser.

The recent demonstration of a novel snapshot imaging polarimeter using the fringe modulation technique shows a promise in building a compact and moving-parts-free device. As just demonstrated in principle, this technique has not been adequately studied. In the effort of advancing this technique, we build a complete theory framework that can address the key issues regarding the polarization aberrations caused by using the functional elements. With this model, we can have the necessary knowledge in designing, analyzing and optimizing the systems. Also, we propose a broader technique that uses arbitrary modulation instead of sinusoidal fringes, which can give us more engineering freedom and can be the solution of achromatizing the system. In the hardware aspect, several important progresses are made. We extend the polarimeter technique from visible to middle wavelength infrared by using the yttrium vanadate crystals. Also, we incorporate a Savart Plate polarimter into a fundus camera to measure the human eye's retinal retardance, useful information for glaucoma diagnosis. Thirdly, a world-smallest imaging polarimeter is proposed and demonstrated, which may open many applications in security, remote sensing and bioscience.

The overall purpose of the dissertation is to design and develop novel optical imaging systems that require minimal or no mechanical scanning to reduce the acquisition time for extracting image data from biological tissue samples. Two imaging modalities have been focused upon: a parallel optical coherence tomography (POCT) system and a volume holographic imaging system (VHIS). Optical coherence tomography (OCT) is a coherent imaging technique, which shows great promise in biomedical applications. A POCT system is a novel technology that replaces mechanically transverse scanning in the lateral direction with electronic scanning. This will reduce the time required to acquire image data. In this system an array with multiple reduced diameter (15μm) single mode fibers (SMFs) is required to obtain an image in the transverse direction. Each fiber in the array is configured in an interferometer and is used to image one pixel in the transverse direction. A VHIS is based on volume holographic gratings acting as Bragg filters in conjunction with conventional optical imaging components to form a spatial-spectral imaging system. The high angular selectivity of the VHIS can be used to obtain two-dimensional image information from objects without the need for mechanical scanning. In addition, the high wavelength selectivity of the VHIS can provide spectral information of a specific area of the object that is being observed. Multiple sections of the object are projected using multiplexed holographic gratings in the same volume of the Phenanthrenquinone- (PQ-) doped Poly (methyl methacrylate) (PMMA) recording material.