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Holographic sensors are photonic layered structures contained in analyte sensitive lms that upon illumination produce monochromatic reflections (λ). The present work reports the fabrication of oxygen and ammonia sensors in Nafi on membranes and hydrocarbon and volatile organic compound sensors in poly(dimethylsiloxane) (PDMS) films. A holographic recording technique was developed to suit these materials consisting of the in situ formation of nanoparticles of 18nm average diameter and their subsequent ordered ablation with a 300mJ laser. The wavelength of the monochromatic reflections depends principally on the refractive index of the resulting layers (n) and the separation between them (Λ). Changes in these parameters are generated by the analyte-sensor interactions and their magnitude can be correlated to the analyte concentration. The strength of these interactions is determined by the thermodynamic properties of the analytes, such as the cohesive energy density (δ^2), and this, was coupled with a photonic model for the prediction of the holographic response. After exposure to different concentrations of the analytes, the kinetics of the responses were determined and the lowest detection limits (LDL) established as follows: Hydrocarbons in PDMS holograms 1% (v/v) in 3s for a range of concentrations from 0-100%; ammonia in Nafi on holograms 0.16% in 100s in the 0-12.5% range; the LDL for oxygen sensing could not be determined although the response was recorded down to 12.5% and up to 100% in 100s. Holographic sensors show competitive responses comparable to commercially available gas sensors for biomedical diagnostics and industrial process monitoring because of their facile fabrication and their shared sensing platform allowing multiplexing.

This dissertation focuses on developing advanced Mid-IR optical devices for chip-scale chemical sensing. Various Mid-IR techniques based on Beer-Lambert’s law offer valuable insights into molecular interactions but suffer from bulkiness and high cost. Towards the compact and cost-effective sensing purpose, many efforts have been made in light sources (e.g., QCLs), photodetectors (e.g., PbSe, MCT detectors), and gas sampling chambers via on-chip photonic waveguides. Despite the progress achieved through these new technologies, there is still plenty of room for enhancing the performance and cost-effectiveness of miniaturized Mid-IR gas sensing systems. Thus, this dissertation explores new photonic engineering pathways to address existing challenges through on-chip integration and downsizing in three core mid-IR gas sensing components, including the light source, detector, and interaction path. In this dissertation, a simple yet versatile and powerful resonant grating platform has been utilized as the foundation to develop innovative engineering methods. Herein, due to the nontrivial properties of High Contrast Gratings (HCGs), such as broadband reflectivity, and high Q factor resonance, I focus mostly on these types of grating resonators. Through a new design, HCGs are used to enhance absorption in uncooled PbSe-based photodetectors. Moreover, for shrinking the interaction path, a high Q factor HCG resonator was designed, showing 600 times light absorption enhancement in a micro-size path length. Furthermore, integrating active HCGs with Parity-Time (PT) symmetry concept offers near-zero bandwidth photonic resonant emission with application in Mid-IR light sources. Besides the exploration of new photonic design methods, another important aspect of this work has been focused on the development of a suitable mid-IR material platform to allow the implementation of the aforementioned photonic design methods. Specifically, a modified chemical deposition method is used to synthesize Oriented-Attached (OA) PbSe nanocrystals (NCs) on amorphous substrates with strong quantum confinement and broad size-tunability. This optimized and cost-effective growth technique demonstrates promising illumination in the Mid-IR range, contributing to the potential of OA PbSe NCs synthesized by this novel method as a material for fabricating Mid-IR photonic components. At the end of this dissertation, an experimental exploration of a low-cost and large-area patterning nanofabrication method is also presented as an extended effort from the core photonic design and novel material synthesis works towards the overarching goal to develop smaller, cost-effective, and efficient on-chip mid-IR optical devices for chemical sensing applications.

The recipes of optical radiative properties manipulation are their materials chemistry, nano/microscale geometry, and transport properties of quasiparticle carriers such as photons, phonons, and electrons. The important technical element in optical properties is the dielectric function of materials, which is different for metals, dielectrics, 2D materials, and phase transition materials. Graphene has a unique electrical conductivity profile which have metallic nature depending on the frequency, but also has a negative thermal expansion coefficient that makes graphene unique. Hence, graphene creates wrinkles when deposited on the substrate as temperature decreases to room temperature from high substrate temperature. We also study phase transition material, particularly vanadium dioxide that transitions from insulating to metallic phase based on temperature change; we investigate its role in far-field thermal radiation. Other transition metal oxides are studied as a thermally and electrically tunable plasmonic gratings: Transition metal oxides include vanadium dioxide, tungsten trioxide, and molybdenum trioxide. The work demonstrates plasmonic phenomena and absorptance/emittance tunability. First, surface plasmon polariton along the graphene (SPPG) when wrinkles are formed above the plasmonic grating is studied. The resonance peak shift is modeled for both magnetic polariton (MP) with inductor-capacitor (LC) circuit and SPPG with Fabry-Perot phase change model. Second, the self-adaptive radiative coating is proposed using vanadium dioxide for high turn-down in emissivity spectrum. The Si high contrast grating (HCG) is introduced on the vanadium dioxide coating to prevent solar absorption by vanadium dioxide layer which have high extinction coefficient in visible to near-infrared region. Lastly, the switching in resonances, transitioning from MP resonance at metallic state to transmission mode obtained from concept of zero contrast grating (ZCG) is described. Overall, the work is aimed to tailor the optical radiative properties of gratings and multilayers used for thermal regulating applications.

Vertical-cavity surface-emitting lasers (VCSELs) are key optical components used in optical communication, datacom, and many other applications. Recently, as 3D sensing technology has become more popular, VCSEL arrays have attracted more attention. As a result, VCSELs with more advanced and improved performance are needed to satisfy the increasing trend. This is very hard to achieve by traditional VCSELs alone. Therefore, it creates an opportunity for VCSELs to integrate with other optical elements.Grating is such a traditional optical element but with many unique properties. It has been studied by researchers for a long time. There are many reasons why grating is an ideal candidate for such integration. Besides its various optical properties, its fabrication is usually very simple as well. Therefore, this thesis will focus on different ways that gratings can be integrated with VCSELs to bring novel and unique properties.First, we will introduce a design toolbox we developed to model such grating structures. With this toolbox, we will demonstrate a novel wavelength tunable VCSEL design. By replacing the traditional VCSEL top mirror by high-contrast grating (HCG) and changing the cavity design, the laser tuning range can be greatly extended. Second, we will discuss a more compact HCG VCSEL architecture by incorporating a low-index oxide spacer. By carefully optimizing HCG design, the highest efficiency HCG VCSEL has been demonstrated. Finally, we will introduce a two-step growth method to fabricate a new grating aperture VCSEL. By replacing the traditional oxide aperture by a grating, large-aperture, single-mode laser can be achieved. In addition, polarization selective emission is also possible. With these three examples, we hope to show the capability of integrating grating structures to VCSELs and pave the road for future VCSEL design.

Understanding the color production mechanisms is important to the advancement of understanding color evolution, ecology, adaptation, and functions. Therefore, investigating how spiders produce colors is a critical piece of the puzzle to fully understand spider biology. In this dissertation, I investigated how spiders produce colors through pigments and biogenic photonic structures using varies techniques. We discovered the presence of eumelanin and carotenoids in spiders, which are both common in nature but were previously thought to be absent in spiders. I also discovered melanosomes – a melanin-containing cellular organelle previously assumed to be a synapomorphy for vertebrates – in spiders. Pigments aside, I described many novel and unique biogenic photonic structures in spiders. The blue color for many tarantulas is produced via specialized setaewith diverse photonic structures within. A phylogenic analysis on the blue traitsiiishowed that despite being a very specific (narrow band) blue color, the blue traits evolved independently at least 8 times. In other words, diverse photonic structures evolved convergently to produce a very specific blue color in tarantulas, suggesting an important visual function for yet to be determined receivers. Among these structures, a flower-shaped multilayer structure is of particular interests due to its ability to attenuate iridescence. This particular structure may inspire the design and fabrication of vibrant, durable colorants in the future. On the other hand, two particular species of peacock spiders showcase extremely angle sensitive iridescence, which produces all the colors within the human visible spectrum with the slightest movement. We determined that this rainbow-iridescent optical effect was produced by unique airfoil-shaped setae with surface nanogratings. These setae also possess an unusual high wavelength resolving capability that may contribute to the design and fabrication of miniature optical components to further advance human light-based technologies.

Although surface-enhanced Raman spectroscopy (SERS) is a spectroscopic technique with unusually high sensitivity and molecular specificity, few practical analytical applications have been implemented that take advantage of its power. Based on what is understood about SERS from the experimental and theoretical research of the past forty years, we developed a few well-defined design principles on the basis of which a reliable and reproducibly manufacturable SERS-active substrate could be fabricated that is highly enhancing, highly uniform, stable, and based on a broad range of metals so that various chemical processes could be probed. Finally, we restricted ourselves to using only readily scalable fabrication techniques. The resulting SERS-active device was a metal over silica, two-dimensional nano-grating that was shown to produce enhancements of ~107 when compared to a smooth surface of the same metal. This SERS substrate also shows unprecedented signal uniformity over square centimeters, and is fabricated using commonly-available foundry-based approaches exclusively. Initially, we explored the properties of a gold-coated substrates in which a first-order grating resonance due to long-range symmetry is augmented by a local resonance due to the individual core-shell grating elements. The SERS properties of such grating systems were systematically studied as a function of various structural parameters such as the grating pitch, the inter-element gap and the thickness of the metal layer. The most enhancing substrates were found to have a grating parameter with a radiative, rather than evanescent, first-order resonance; a sufficiently small gap between nearest neighbor grating elements to produce near-field interactions; and a gold layer whose thickness was larger than the electronic mean-free-path of the conduction electrons, so as to ensure a high conductivity for the metal layer to sustain strong surface plasmons.We applied these same architectural principles to metals other than gold, and concluded that every workable metal (and virtually any material with sufficiently high electrical conductivity) when appropriately nanostructured, has the potential to be an efficient SERS substrate. The use of materials for SERS beyond silver and gold, has significant advantages, most importantly, allowing SERS to be used to study the surface chemistry and catalysis taking place on metals with more interesting chemistries than those of Au and Ag. Additionally, SERS substrates can be fabricated from high natural abundance, low cost materials. This was illustrated by producing SERS substrates using copper, aluminum, and nickel in addition to silver and gold which were used as benchmarks. All five metals were found to yield high SERS intensities. The variation of the SERS enhancement among them is ascribed mainly to local field effects, with the (larger) grating-based enhancement making an approximately equivalent contribution to the SERS enhancement of the five metals. This conclusion is supported by local electric field simulations. The utility of these new grating-based SERS substrates was demonstrated by implementing them in chemical analysis in both aqueous and gas phases for which, for example, we were able to readily detect opioids such as fentanyl and morphine at concentrations as low as less than one part per billion. Additionally, we have made good progress toward integration of this substrate architecture into a microfluidic channel for a higher degree of sample workup and control.

In controlling interacting nano- and micro-particles as well as biomolecules, one gains access to a broad range of applications spanning from self-assembly and nanofabrication to creating useful soft matter constructs. This dissertation investigates interacting superparamagnetic particles residing on two different patterned micro-magnetic thin-film platforms: zigzag CoFe wires that support stationary domain walls, and NiFe shapes that yield mobile domains. Interactions between these particles, the underlying stationary or mobile magnetic domains, and external magnetic fields give rise to tunable, ordered micro-particle arrays (clusters) that can be remotely activated and maneuvered. Seamless schemes to self-assemble, disassemble, transport, and reconstruct ordered planar arrays of fluid-borne microspheres are illustrated with the CoFe wires while their Brownian fluctuations are shown to provide an elegant means to probe the local energy landscape in which the spheres are constrained to move. Finally, a magneto-optical micro grating is developed using mobile domains in NiFe to modulate inter-particle spacing and thus diffract and steer photon beams with high precision. The potential for a magneto-optical lock and other photonic applications with this approach are discussed.

High efficiency photovoltaic solar cells are expected to continue to be important for a variety of terrestrial and space power applications. Solar cells made of optically thick materials often cannot meet the cost, efficiency, or physical requirements for specialized applications and, increasingly, for traditional applications. This dissertation investigates improving the performance of single-junction GaAs solar cells by incorporating InGaAs/GaAs quantum wells and quantum dots to increase their spectral response bandwidth, and by incorporating structures that confine light in the devices to improve their absorption of it. InGaAs/GaAs quantum dots-in-wells extend the response of GaAs homojunction devices to wavelengths >1200 nm. Nanoparticles that are randomly deposited on the top of optically thick devices scatter light into waveguide modes of the device structures, increasing their absorption of electromagnetic energy and improving their short-circuit current by up to 16%. Multiply periodic diffractive structures have been optimized using rigorous software algorithms and fabricated on the back sides of thin film quantum dot-in-well solar cells, improving their spectral response at wavelengths 850 nm to 1200 nm, where only the quantum dot-in-well structures absorb light, by factors of up to 10. The improvement results from coupling of diffracted light to waveguide modes of the thin film device structure, and from Fabry-Perot interference effects. Simulations of absorption in these device structures corroborate the measured results and indicate that quantum well solar cells of ~2 µm in thickness, and which are equipped with optimized backside gratings, can achieve 1 Sun Airmass 0 short-circuit current densities of up to ~5 mA/cm2 (15%) greater than GaAs homojunction devices, and of up to >2 mA/cm2 (7%) greater than quantum well devices, with planar back reflectors. A combination of Fabry-Perot interference and diffraction into waveguide modes of the thin devices is shown to dominate the simulated device response spectra. Simulations also demonstrate the importance of low-loss metals for realizing optimal light trapping structures. Such device geometries are promising for reducing the cost of high efficiency solar cells that may be suitable for a variety of traditional and emerging applications.

Biomolecular imaging enables localization and characterization of biomolecules at the cellular and tissue levels in order to better understand their roles in biological organisms. Although a plethora of imaging techniques is available, there is a need to improve current imaging methodologies and apply them for selective analyses of complex biological specimens. The work described in this thesis is related to development and applications of spectral imaging and imaging mass spectrometry (IMS) methodologies. Spectral imaging uses either labeling dyes or native chromophores to visualize biomolecules in cells and tissues under a specialized light microscope, while IMS provides direct detection and analysis of biomolecules on tissue surfaces with preserved spatial distribution.In this initial study, multimodal spectral imaging of cells, cellular organelles, and tissues was performed on a light microscope upon the addition of a transmission diffraction grating. The instrument concurrently recorded spectral images by fluorescence, darkfield, brightfield, and differential interference contrast (DIC) spectral microscopy. Fluorescence signals originating from fluorescently labeled biomolecules in cells were collected through triple or single filter cubes, separated by the grating, and were imaged using a charge-coupled device (CCD) camera. Cellular components such as nuclei, cytoskeleton, and mitochondria were spatially separated by the fluorescence spectra of the fluorophores present in them, providing detailed multi-colored spectral images of cells. Additionally, the grating-based spectral microscope enabled measurement of scattering and absorption spectra of unlabeled cells and stained tissue sections using darkfield and brightfield spectral microscopy, respectively. In the second project, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) was utilized to visualize the protein spatial distribution on tissue surfaces. Our study has been focused on imaging of proteins in kidney tissue sections originating from apparently healthy (normal) mice and mice with polycystic kidney disease (PKD). Reconstruction of protein ion maps and identification of proteins by on-tissue enzymatic digestion were performed. MALDI-MS images were correlated with histological features obtained by hematoxylin and eosin staining, providing localization of peptides in different parts of the kidney (renal pelvis, medulla, and cortex). Nano-HPLC was coupled with imaging mass spectrometry to identify proteins in kidney tissue sections. Statistical analyses such as principle component analysis (PCA) was employed to achieve tissue classification and differentiate between healthy and diseased tissues. Experiments are underway to discover and validate proteins that can become potential biomarkers of PKD. In summary, we demonstrated that fluorescence, scattering, and absorption spectral images of cells can be acquired by incorporation of a transmission diffraction grating into a light microscope. The present spectral imaging methodology provides a readily affordable approach for multimodal spectral characterization of biological cells and other specimens. A reproducible MALDI-IMS workflow was established and resulted in protein mass distribution maps of normal and PKD kidney tissues. Statistical comparison of MALDI-MS images provides classification of healthy and diseased tissues. Several proteins were localized in tissues and their identity will be further confirmed by HPLC combined with tandem mass spectrometry (MS/MS).

Blue phase liquid crystals (BPLCs) have a delicate lattice structure existing between chiral nematic and isotropic phases, with a stable temperature range of about 2 K. But due to short coherent length, these self-assembled nano-structured BPLCs have a fast response time. In the past three decades, the application of BPLC has been rather limited because of its narrow temperature range. In 2002, Kikuchi et al. developed a polymer stabilization method to extend the blue-phase temperature range to more than 60 K. This opens a new gateway for display and photonic applications. In this dissertation, I investigate the material properties of polymer-stabilized BPLCs. According the Gerber’s model, the Kerr constant of a BPLC is linearly proportional to the dielectric anisotropy of the LC host. Therefore, in the frequency domain, the relaxation of the Kerr constant follows the same trend as the dielectric relaxation of the host LC. I have carried out experiments to validate the theoretical predictions, and proposed a model called extended Cole-Cole model to describe the relaxation of the Kerr constant. On the other hand, because of the linear relationship, the Kerr constant should have the same sign as the dielectric anisotropy of the LC host; that is, a positive or negative Kerr constant results from positive (∆ε > 0) or negative host LCs (∆ε < 0), respectively. BPLCs with a positive Kerr constant have been studied extensively, but there has been no study on negative ∆ε polymer-stabilized BPLCs. Therefore, I have prepared a BPLC mixture using a negative ∆ε LC host and investigated its electro-optic properties. I have demonstrated that indeed the induced birefringence and Kerr constant are of negative sign. Due to the fast response time of BPLCs, color sequential display is made possible without color breakup. By removing the spatial color filters, the optical efficiency and resolution density are both tripled. With other advantages such as alignment free and wide viewing angle, polymer-stabilized BPLC is emerging as a promising candidate for next-generation displays. However, the optical efficiency of the BPLC cell is relatively low and the operating voltage is quite high using conventional in-plane-switching electrodes. I have proposed several device structures for improving the optical efficiency of transmissive BPLC cells. Significant improvement in transmittance is achieved by using enhanced protrusion electrodes, and a 100% transmittance is achievable using complementary enhanced protrusion electrode structure. For a conventional transmissive blue phase LCD, although it has superb performances indoor, when exposed to strong sunlight the displayed images could be washed out, leading to a degraded contrast ratio and readability. To overcome the sunlight readability problem, a common approach is to adaptively boost the backlight intensity, but the tradeoff is in the increased power consumption. Here, I have proposed a transflective blue phase LCD where the backlight is turned on in dark surroundings while ambient light is used to illuminate the displayed images in bright surroundings. Therefore, a good contrast ratio is preserved even for a strong ambient. I have proposed two transflective blue phase LCD structures, both of which have single cell gap, single gamma driving, reasonably wide view angle, low power consumption, and high optical efficiency. Among all the 3D technologies, integral imaging is an attractive approach due to its high efficiency and real image depth. However, the optimum observation distance should be adjusted as the displayed image depth changes. This requires a fast focal length change of an adaptive lens array. BPLC adaptive lenses are a good candidate because of their intrinsic fast response time. I have proposed several BPLC lens structures which are polarization independent and exhibit a parabolic phase profile in addition to fast response time. To meet the low power consumption requirement set by Energy Star, high optical efficiency is among the top lists of next-generation LCDs. In this dissertation, I have demonstrated some new device structures for improving the optical efficiency of a polymerstabilized BPLC transmissive display and proposed sunlight readable transflective blue-phase LCDs by utilizing ambient light to reduce the power consumption. Moreover, we have proposed several blue-phase LC adaptive lenses for high efficiency 3D displays.

Exciton dynamics in semiconductor nanostructures are dominated by the effects of many-body physics. The application of coherent spectroscopic tools, such as two-dimensional Fourier transform spectroscopy (2dFTS), to the study of these systems can reveal signatures of these effects, and in combination with sophisticated theoretical modeling, can lead to more complete understanding of the behaviour of these systems. 2dFTS has previously been applied to the study of GaAs quantum well samples. In this thesis, we outline a precis of the technique before describing our own experiments using 2dFTS in a partially collinear geometry. This geometry has previously been used to study chemical systems, but we believe these experiments to be the first such performed on semiconductor samples. We extend this technique to a reflection mode 2dFTS experiment, which we believe to be the first such measurement. In order to extend the techniques of coherent spectroscopy to structured systems, we construct an experimental apparatus that permits us to control the beam geometry used to perform four-wave mixing reflection measurements. To isolate extremely weak signals from intense background fields, we extend a conventional lock-in detection scheme to one that treats the optical fields exciting the sample on an unequal footing. To the best of our knowledge, these measurements represent a novel spectroscopic tool that has not previously been described.

Vertical cavity surface emitting lasers (VCSELs) have become of large commercial importance over the last two decades. They have become the dominant low cost, low power coherent sources in many applications such as optical sensing and short distance data communication.Despite their great success, there remain opportunities for improvement. Almost all commercially produced VCSELs are fabricated on structures based on a GaAs substrate. This restricts their wavelength range to between 650 and 1300 nm. Many potential applications exist at wavelengths outside of this range, so much work has gone into realizing VCSELs on other substrates. Though they have been realized, this has typically come with complexity that increases cost of producing such VCSELs. Of particular interest are InP-based VCSELs, which allow for emission at the wavelengths of 1320 nm and 1550 nm, two regions of high importance for optical communications applications.Another area of much research has been improving the modal characteristics of VCSELs. Typical VCSELs will lase in two polarization-degenerate optical modes. In addition, due to their structure, lateral optical modes also appear when a typical VCSEL's aperture becomes more than a few microns in size, limiting their output power. For high performance optical communications and sensing, a single mode laser is essential, so solving these mode problems is important.Next generation optical communication systems also require sources with an array of lasers of multiple output wavelengths or a tunable wavelength source that can be quickly tuned over a wide range of wavelengths. Schemes for both approaches have been implemented on VCSELs though various limitations of the current approaches have prevented them of being of large commercial importance to date. Tunable VCSELs have been limited in wavelength tuning speed by the thickness of their movable mirror. A commercially viable approach for an array of VCSELs of multiple wavelengths has also been difficult to achieve - most approaches shown to date require complex growth methods and the have not been able to achieve controllable wavelength spacing.High contrast gratings (HCGs) have emerged as an exciting new tool for achieving optical features such as broadband mirrors, planar lenses, and high quality factor resonators. Of particular use for VCSELs is a broadband mirror. These high contrast gratings in addition to acting as a mirror have features that can be exploited for many applications such as polarization differentiation and definable phase among others. HCGs are an exciting new tool for many optical applications.In this dissertation, we show how a high contrast grating can potentially solve several of the issues facing VCSELs and open new application spaces for VCSELs. First, we introduce the state of the art in VCSEL research and give a detailed overview of major areas of interest in VCSEL research. Next, we introduce high contrast gratings, discuss their implementation onto VCSELs, and demonstrate how they can be used to achieve more ideal modal qualities in the VCSEL, a single polarization mode as well as a larger area single transverse mode device. Then we show how the high contrast grating can be used in a tunable VCSEL to achieve ultra high speed tuning. Following that discussion, we shift our focus to implementing high performance, low cost VCSELs on InP with an HCG, showing two different approaches: a deposited Si HCG sitting on SiO2 and a monolithically-grown InP HCG. We conclude with a discussion of two approaches to achieve controllable arrays of VCSELs emitting at multiple wavelengths. The high contrast grating may be an important tool to achieving higher performance VCSELs, and VCSELs with features that enable new applications.

Details of the design, fabrication, and characterization of silicon-on-insulator (SOI) nanophotonic devices are presented. Shallow etched rectangular profile gratings are demonstrated to couple free space light into planar SOI waveguides with efficiencies exceeding 20%. Parabolic planar solid immersion mirror (PSIM) couplers are shown to inject light into SOI photonic crystal waveguides with efficiencies exceeding 99%. Wavelength dependent low-loss propagation through SOI photonic crystal waveguides is reported, and the incorporation of nonlinear materials is considered.

In this thesis, light transmission through a single sub-wavelength slit in a silver thin film with periodic gratings at the exit side of the slit has been studied in both the visible and mid-infrared wavelength ranges. In the visible wavelength range, we first investigate the enhancement of plasmonic light beaming efficiency by near field resonance in a subwavelength metallic slit-groove beaming structure. We show that by varying the film thickness and the separation distance of the beaming grating, the intensity of the near field can be greatly enhanced by resonance, which leads to the increase of the beaming efficiency. Moreover, we obtain a nanocavity above the nanoslit by integrating a metal nanostrip with the beaming structure. The resonance of this nanocavity can further enhance the near field intensity and improve the beaming efficiency. We also show that light beaming in mid-infrared is mainly controlled by 'spoof' surface plasmons. We take account of both the dispersion relation and the phase-matching condition of 'spoof' surface plasmons to obtain good beaming efficiency. Through engineering the geometry of the grating structures, we can achieve the desired near field and far field distribution in mid-infrared.

We introduce achromatic polarization gratings (PGs) as broadband polarizing beam splitters, which exhibit practically ~100% efficient diffraction over a wide range of spectrum. We have experimentally demonstrated high-quality achromatic PGs fabricated using holographic photoalignment techniques for liquid crystal (LC) materials. Non-ideal diffraction behaviors of the PGs have been investigated beyond the paraxial limitations (i.e., small grating periods, oblique incidence, and finite gratings) via extensive numerical analysis based on the finite-difference time-domain method. Design and fabrication of small-period PGs are also discussed to show how to achieve high diffraction efficiency and large diffraction angles at the same time. Three key innovative technologies utilizing the unique diffraction properties of the PGs have been introduced and experimentally demonstrated. The first application for light-efficient LC displays is the polymer-PG display. We have developed a prototype projector based on the polymer-PG display as a viable solution for ultra-bright pico-projector applications. Second, two novel beam steering concepts based on the PG diffraction have been proposed: a non-mechanical, wide-angle beam steering system using stacked PGs and LC waveplates and the Risley grating as a thin-plate version of the Risley prism. The third PG application is in advanced imaging and non-imaging spectropolarimetry. In the last part of this Dissertation, we introduce a polarization-type Fresnel zone plates (P-FZPs), comprising of spatial-variant linear birefringence or concentric PG (CPG) patterns. We have experimentally demonstrated high-quality P-FZPs, which exhibit ideal Fresnel-type lens effects, formed as both LC polymer films and electro-optical LC devices. In summary, we have explored the fundamental diffraction behavior of the polarization gratings and their applications in various optics and photonics technologies. We conclude this Dissertation with our suggestions of a number of potential innovations and advances in technologies that can be enabled by polarization gratings and related technologies.

The objective of this research is to study the functional relationship between amplitude and phase images, using a sinusoidal test function. Amplitude and phase sine wave gratings were produced and scanned. It was found that the phase image closely reproduces the amplitude image for low spatial frequencies, but the accuracy of reproduction falls off at high spatial frequencies.