Optical interconnects are important to the future development of microelectronics. Volume grating couplers (VGCs) provide a compact, efficient coupling mechanism that is compatible with microelectronics fabrication processes. In this dissertation, some of the performance characteristics of VGCs are investigated. Also, integration of VGCs with Sea of Polymer Pillars (SoPP), an emerging high-density input/output interconnect technology, is demonstrated and its performance quantitatively investigated. First, the polarization-dependent performance of VGCs is analyzed, and the design constraints for achieving high-efficiency polarization-dependent and polarization-independent VGCs are examined. The effects of loss on VGC performance are also presented. Then, the wavelength response of VGCs and its dependence on grating parameters is quantitatively examined. Experimental demonstrations of polarization-dependent and polarization-independent VGCs are then presented. Finally, a VGC integrated with a SoPP is demonstrated and its performance characterized.

Methods for analysis and optimization of volume holographic recording are presented for two main groups of applications. In the first group of applications (mainly storage systems), the designs and the techniques of volume holography are well known and the main optimization effort is finding the proper material to store the holograms. One of the results of this research is complete global optimization of dynamic range and sensitivity in two-center recording that is the best technique for persistent rewritable storage. For this purpose, a complete theoretical analysis as well as experimental demonstration is presented. Also, other effects and processes such as electron tunneling and recording at high temperature are considered for possible improvement of the dynamic range of the material. For the second group of applications (mainly holographic optical elements), the focus of this research is on analysis and optimization of the design of the volume holograms in contrast to material optimization. A new method (multi-grating method) is developed for the analysis of an arbitrary hologram that is based on the representation of the hologram as the superposition of several plane wave gratings. Based on this method, a new class of optical devices that integrates the functionalities of different optical elements into a simple volume hologram is introduced and analyzed. As a result, very compact, low cost, and easy to use devices such as portable spectrometers can be made with particular applications in biological and environmental sensing.

Polymer liquid crystal possesses advantages of polymer in chemical industry and liquid crystal in display industry,so it is attracted more attention in science and technology. Diacrylate is a polymer liquid crystal with photosensitive property, so ,it can be applied to optical storage . He-Ne laser induced polymerization in diacrylate mesogen RM257 and RM82 had been verified in previous study. Furthermore, holography pattern can be recorded in RM257 and RM82 by controlling both the temperature of sample and the time of exposing. In this study, we consider the study of nonlinear optical properties of diacrylate using Z-SCAN techeique.¡¨Z-SCAN¡¨ is a simply yet highly sensitive single-beam experimential technique ,it can be used to measure both nonlinear absorption and nonlinear refraction.In this study ,we measured effect of absorption of diacrylate in irradiation of He-Ne laser using Z-SCAN technique.To investigate the reason that He-Ne laser induced polymerization in both RM257 and RM82.

The laser-induced holographic gratings in the Azo dye-doped PMMA thin films with liquid crystal were investigated by changing the temperature of the sample, the angle of two writing beams and the rubbing. The high power Q-switch pulse laser has been used as the writing beams and the He-Ne cw laser has been used as a real-time probe beam to detect the first order diffraction singals. The grating are the results of photo-isomerization of azo dye and diffusions of liquid crystal. The model has been established to analyze the first order diffraction signals in order to understand the mechanism of grating and the effect of temperature and angle.

In this thesis, a 6-beam combiner using multiplexed holograms in dye-doped polymer is investigated. It is realized by recording six superimposed holographic gratings, which show uniform diffraction efficiency. The coupled wave theory for N superimposed gratings is more generalized and is used to analyze the amplitudes of diffracted waves in three different boundary conditions. Multiple-ring diffracted beam analysis is proposed to determine the dynamic range of a holographic material. The M/# is evaluated by recording a single hologram and counting the number of ring patterns in the diffracted beam. This analysis is extended to assess the equalized grating strength of N superimposed holograms. Six holograms with the equalized grating strength which can be assigned within the dynamic range of our material and show maximum diffraction efficiency are recorded. The phase locking of five beams to one reference beam is performed using PZT controller. The designs of lock-in amplifier, ramp generator and servo using commercial chips are demonstrated. The readout set-up used to split one single beam into six coherent copies is presented. The function of each part of the PZT controller in the readout set-up is discussed in detail. The intensity profile of an N-beam combiner is investigated by varying the phase angle between adjacent input waves. The entire solution which describes the amplitude of a combined beam is derived from generalized coupled wave theory. A simplified experimental set-up without a complicated PZT controller is demonstrated using a planoconvex lens. In order to provide six coherent light sources in future work, the injection locking of a single laser diode to the master laser diode is performed. An expected read-out setup is proposed to carry out both the achievement of six coherent sources and a 6 beam combination.

A novel optical calorimetry approach is proposed for the dosimetry of therapeutic radiation, based on the optical technique of Digital Holographic Interferometry (DHI). This detector determines the radiation absorbed dose to water by measurement of the refractive index variations arising from radiation induced temperature increases. The output consists of a time series of high resolution, two dimensional images of the spatial distribution of the projected dose map across the water sample. This absorbed dose to water is measured directly, independently of radiation type, dose rate and energy, and without perturbation of the beam. These are key features which make DHI a promising technique for radiation dosimetry. A prototype DHI detector was developed, with the aim of providing proof-of-principle of the approach. The detector consists of an optical laser interferometer based on a lensless Fourier transform digital holography (LFTDH) system, and the associated mathematical reconstruction of the absorbed dose. The conceptual basis was introduced, and a full framework was established for the measurement and analysis of the results. Methods were developed for mathematical correction of the distortions introduced by heat di usion within the system. Pilot studies of the dosimetry of a high dose rate Ir-192 brachytherapy source and a small eld proton beam were conducted in order to investigate the dosimetric potential of the technique. Results were validated against independent models of the expected radiation dose distributions. Initial measurements of absorbed dose demonstrated the ability of the DHI detector to resolve the minuscule temperature changes produced by radiation in water to within experimental uncertainty. Spatial resolution of approximately 0.03 mm/pixel was achieved, and the dose distribution around the brachytherapy source was accurately measured for short irradiation times, to within the experimental uncertainty. The experimental noise for the prototype detector was relatively large and combined with the occurrence of heat di usion, means that the method is predominantly suitable for high dose rate applications. The initial proof-of-principle results con rm that DHI dosimetry is a promising technique, with a range of potential bene ts. Further development of the technique is warranted, to improve on the limitations of the current prototype. A comprehensive analysis of the system was conducted to determine key requirements for future development of the DHI detector to be a useful contribution to the dosimetric toolbox of a range of current and emerging applications. The sources of measurement uncertainty are considered, and methods suggested to mitigate these. Improvement of the signal-to-noise ratio, and further development of the heat transport corrections for high dose gradient regions are key areas of focus highlighted for future development.

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Solar energy is the most abundant source of renewable energy available. The relatively high cost prevents solar photovoltaic (PV) from replacing fossil fuel on a larger scale. In solar PV power generation the cost is reduced with more efficient PV technologies. In this dissertation, methods to improve PV conversion efficiency with holographic optical components are discussed. The tandem multiple-junction approach has achieved very high conversion efficiency. However it is impossible to manufacture tandem PV cells at a low cost due to stringent fabrication standards and limited material types that satisfy lattice compatibility. Current produced by the tandem multi-junction PV cell is limited by the lowest junction due to series connection. Spectrum-splitting is a lateral multi-junction concept that is free of lattice and current matching constraints. Each PV cell can be optimized towards full absorption of a spectral band with tailored light-trapping schemes. Holographic optical components are designed to achieve spectrum-splitting PV energy conversion. The incident solar spectrum is separated onto multiple PV cells that are matched to the corresponding spectral band. Holographic spectrum-splitting can take advantage of existing and future low-cost technologies that produces high efficiency thin-film solar cells. Spectrum-splitting optical systems are designed and analyzed with both transmission and reflection holographic optical components. Prototype holograms are fabricated and high optical efficiency is achieved. Light-trapping in PV cells increases the effective optical path-length in the semiconductor material leading to improved absorption and conversion efficiency. It has been shown that the effective optical path length can be increased by a factor of 4n2 using diffusive surfaces. Ultra-light-trapping can be achieved with optical filters that limit the escape angle of the diffused light. Holographic reflection gratings have been shown to act as angle-wavelength selective filters that can function as ultra-light-trapping filters. Results from an experimental reflection hologram are used to model the absorption enhancement factor for a silicon solar cell and light-trapping filter. The result shows a significant improvement in current generation for thin-film silicon solar cells under typical operating conditions.

Optical testing often requires a measurement of the phase difference between light from two different optical systems. One system is a master or reference system, and the other is a sample or test system. In the optical shop, the reference may be a precision optical surface and the test system may be a newly fabricated surface. A computer generated hologram is a geometric pattern that can be used as a precise reference in an optical test. Computer-generated holograms can be used to make reference systems that would be very difficult to make by other methods. Various encoding methods for making computer-generated holograms are discussed, and a new method is presented that can easily be used on image recorders intended for image processing applications. This general encoding method has many characteristics in common with earlier computer-generated holograms. Examples are given to demonstrate the properties of synthetic holograms and the differences among different encoding techniques. Geometric ray tracing is an essential part of the process of developing holograms for optical systems. A computer ray-trace code was developed to model the optical performance of equipment used in optical testing. This program was used to obtain numeric coefficients that describe the optical properties (optical path) needed to define a reference wavefront. A review of interferometer design leads to a discussion of how the hologram functions as a part of the interferometer and of the limitations to the computer-generated hologram. The diffraction pattern from the hologram, observed in the focal plane of a lens, is the key to understanding the use and limitations of the hologram in an interferometer. A detailed prescription is given for making a computer-generated hologram for a commercial interferometer designed for use with holograms. Problems of finding the proper focal point, the correct hologram size, and preparation of the final hologram image are discussed. An example of an actual test is included. Finally, an analysis of various errors encountered and the limitations of the methods used is presented. Within these limitations, computer-generated holograms can easily and routinely be used to test aspheric optical components.

During the past few years there has been a significant interest in spectrum splitting systems to increase the overall efficiency of photovoltaic solar energy systems. However, methods for comparing the performance of spectrum splitting systems and the effects of optical spectral filter design on system performance are not well developed. This dissertation first establishes a method to analyze and compare spectrum splitting systems with different filters, PV cells types and geometries. The method examines the system conversion efficiency in detail and the role of optical spectral filters. A new metric termed the Improvement over Best Bandgap is defined which expresses the efficiency gain of the spectrum splitting system with respect to a similar system that contains the highest constituent single bandgap photovoltaic cell. Also, this work expands the analysis on dispersive spectrum splitting systems. The dispersive effects of transmission type filters are evaluated using a cross-correlation analysis. Lastly, this work presents a grating-over-lens design for dispersive spectrum splitting. In this geometry, a transmission grating is placed at the entrance of a lens. Part of the incident solar spectrum is diffracted off-axis from normal incidence to the lens. The diffracted spectral range comes to a focus at an off-axis point and the undiffracted spectrum comes to a focus at the paraxial focus of the lens. Since the diffracted wave is planar and off-axis, the off-axis focal points suffer from aberrations that increase system loss. In this work, a novel aberration compensation technique is presented using non-planar transmission gratings recorded using a conjugate object beam to modify the off-axis wavefront. Diverging sources are used as conjugate object and reference beams. The spherical waves are incident at the lens and the grating is recorded at the entrance aperture of the solar concentrator. The on-axis source is adjusted to produce an on-axis planar wavefront at the hologram plane. The off-axis source is approximated to a diffraction limited spot producing a non-planar off-axis wavefront on the hologram plane. Illumination with a planar AM1.5 spectrum reproduces an off-axis diffraction-limited spot on the focal plane. Models and experimental data are presented to quantify the reduction in losses achieved with aberration correction.