Near normal incidence multilayer mirrors are optical elements that are suitable for the extreme ultraviolet wavelength (EUV) region where applications include lithography, astronomy, and microscopy. Multilayer mirrors are made from alternating layers of two materials, called the "absorber" and "spacer," with the thickness of the layers designed such that reflections from each interface add in phase resulting in a large overall reflectivity. The criteria I used for the selection of six new material pairs included achieving the maximum theoretical reflectivity while taking into consideration the possible structural properties of the interfaces based on binary phase diagrams. The pairs were: C-Cu, B₄C-Ag, B₄C-Sn, Y-Pd, Be-Mo, and Be-Y. My experimental results on sputtered C-Cu and B₄C-Ag multilayers showed that they are not suitable as mirror materials due to the formation of discontinuous layers of Cu and Ag for small bilayer periods Λ. I also found it not possible to sputter tin films with small enough interfacial roughness values that would result in useful B₄C-Sn mirrors. My analysis of Y-Pd multilayers showed asymmetric alloying at the interfaces with an approximately 40 Å thick alloy region at the Y on Pd interface which would result in negligible mirror reflectivity. I used one of our molecular beam epitaxy (MBE) machines to attempt to grow single crystal Be-Mo mirrors. Although my attempts were unsuccessful to date, this combination cannot be excluded due to various problems with the MBE sample manipulator during the growth study. Finally I used the same MBE machine to grow Be-Y mirrors with up to 40 bilayers. These multilayers had extremely smooth interfaces (σ = 3.5-4.5 A) with a predicted mirror reflectivity larger than 65%. I found the stability of the Be-Y interfaces to be excellent under atmospheric long term storage. An X-ray photoelectron spectroscopy (XPS) annealing study I conducted also showed stable interfaces for temperatures of up to 200°C. Be-Y mirrors should be suitable for a variety of applications including EUV-lithography.

The optical properties of planar semiconductor microstructures and three-dimensional nanostructures containing narrow linewidth In₀.₀₄Ga₀.₉₆As quantum wells are studied in this dissertation. The interaction of quantum-well excitons with light in environments different from free space gives a pronounced effect on the optical response. N periodically arranged quantum wells are coupled to each other by light leading to N exciton-polariton eigenmodes. Each eigenmode is characterized by a distinct energy and radiative lifetime depending on the periodicity of the quantum wells. For a period of about half the excitonic transition wavelength, linear measurements of reflection, transmission, and absorption show significant features of the light-coupled eigenmodes. At Bragg periodicity, the oscillator strengths of all quantum well excitons are concentrated into one superradiant mode resulting in an N times increased radiative decay rate. The slope of the reflectivity linewidths versus N gives the radiative linewidth of the quantum well exciton. For off-Bragg periodicity, however, other eigenmodes become optically active and show their features in reflection and absorption spectra. Oxide-aperture three-dimensional nanocavities containing a single quantum well are investigated. The discrete transverse modes due to the lateral confinement of the optical field are observed in empty cavities with various aperture sizes. The linewidth measurements of the cavity modes show quality-factor values around 2000 for aperture diameters down to 2 μm. This is high enough to give a strong light-coupling effect in the nonperturbative regime, named normal mode coupling or vacuum Rabi splitting. The anti-crossing behavior of exciton and cavity modes for a 2 μm diameter aperture cavity is measured in transmission by temperature tuning of the exciton resonance through the lowest transverse cavity mode. A minimum splitting value of 3.9 meV and a splitting-to-linewidth ratio of 4.9 are obtained. Then, nonlinear pump-probe measurements on nanocavities with several aperture sizes are performed. The transition from the nonperturbative regime to the weak coupling regime is observed as the pump power increases. From the measured saturation powers for various aperture diameters, a photon density of 90 photons/μm² is found necessary to saturate the normal-mode peaks. The effect of quantum fluctuations of the light field in the nonperturbative regime of planar semiconductor microcavities containing quantum wells is studied. A pronounced third transmission peak lying spectrally between the two normal modes is observed in resonant single-beam-transmission and pump-probe measurements. Measurements on three-dimensional nanocavities confirm the important role of guided modes for this intriguing effect.

An achromatic shearing phase sensor is proposed as a phasing technique for the alignment of segmented telescopes. The sensor is based upon a shearing interferometer using two-wavelength interferometry methods. The two beams are created with a diffraction grating. The diffracted orders are re-imaged such that the pupil plane is focused onto a CCD array with a shear displacing the two orders. The amount of shear is equal to the size of the re-imaged segments. The sensor was measured to have a capture range of at least 5 μm, and an accuracy of 0.3 μm or better. The repeatability was 0.1 vm. The sensor is very sensitive to field dependent aberrations in its optical design but the resulting errors can be calibrated. The sensor is an improvement over similar technologies because it can measure and compensate for segment aberrations with tilt and piston adjustments. The sensor is compatible with many mature interferometry techniques and can be used with extended and broadband sources.

A rotating wafer scanner was designed and developed in order to determine its operational feasibility and advantages over a linear wafer scanner. The scanner was first designed to operate at atmosphere. Each of its constituent parts were independently tested and when the final system was evaluated a 0.2 mum detection limit was observed. The latter result prompted the design and development of a vacuum rotating wafer scanner. The data obtained during the design and evaluation of the constituent parts of the latter system showed that particle detection in a vacuum is feasible.

This dissertation describes the development, calibration, and testing of the adaptive optics system for the 6.5 m Multiple Mirror Telescope. By employing a deformable secondary mirror, the MMT adaptive optics system uniquely solves several problems typical of astronomical adaptive optics systems. Extra components are eliminated, improving throughput and reducing emissivity. Since the adaptive secondary is integral to the telescope, a corrected beam is presented to any instrument mounted at Cassegrain focus. The testing of an adaptive mirror, which is large and convex, poses a new and difficult problem. I present a test apparatus that allows complete calibration and operation, in closed-loop, of the entire adaptive optics system in the laboratory. The test apparatus replicates the optical path of the telescope with a wavefront error of less than 500 nm RMS. To simulate atmospheric turbulence, machined acrylic plates are included. A phase-shifting interferometer allows calibration of the Shack-Hartmann wavefront sensor and reconstruction algorithms; comparisons agree to one-third of the root-mean-square wavefront. First, techniques were developed to align the apparatus and measure residual aberration. Then, the wavefront sensor was calibrated by measuring its response to introduced tilt. Lastly, a Fourier wave-optics approach was used to produce a modal wavefront reconstructor. The adaptive secondary mirror uses electro-magnetic force actuators. Capacitive position sensors are placed at each actuator to permit control of the mirror shape without measuring the reflected wavefront. These sensors have nanometer resolution, but require calibration. To calibrate the sensors, I developed a small optical instrument which measures the thickness of transparent films to an absolute accuracy of 5 nm with a precision of 2 nm. The device has applications far beyond the scope of this research. Twenty-four of these optical gap sensors have been built to calibrate the 336 capacitive sensors on the adaptive secondary mirror. Mirror displacements measured using gap sensors and a phase-shifting interferometer agree to 2 percent of the displacement. The gap sensors allow for quick and accurate calibration of the capacitive sensors without the difficulty of installing an interferometer on the telescope.

A major paradigm shift in the design of large telescopes is currently in progress. In order to increase the size of a telescope primary mirror, current designs use mirrors that are comprised of multiple segments instead of one monolithic piece. While this approach allows for larger primary mirrors than the monolithic approach, new challenges arise. One of the primary challenges is to accurately, rapidly, and cost-effectively test the multiple asphere segments. This dissertation provides a thorough design analysis and experimental validation on a novel method, proposed by Burge and Anderson, for measuring off-axis aspherical surfaces using test plate and computer-generated holograms. This new method is optimal for measuring segments of aspheric primary mirrors, and can be applied to any aspheric surface, convex or concave. It interferometrically compares the aspheric surface with a nearly matching spherical reference surface and uses CGH to compensate the aspherical departure. Like other Fizeau-type interferometric tests, high accuracy is achieved economically since the spherical reference is the only surface that directly affects the measurement. This technique is optimal for testing primary mirror segments where all the different off-axis pieces of the asphere can be measured with a single test plate, replacing only the smaller hologram. The most important property of this test for segmented mirrors is the fine control of the curvature provided by using a reference plate in close proximity to the aspherical surface being measured. This allows all the segments to be separately manufactured, assumes that they will fit together to form a single aspheric surface. In this dissertation, I examine, optimize, and validate this novel method, making it readily available for future telescope designers/manufacturers. First, the quantitative analysis on how segmentation tightens the testing requirements during fabrication and alignment provides valuable information in determining essential telescope parameters such as segment size, F/#, fabrication and alignment specifications. Secondly, the detailed optimization processes show how the test system can be designed and built to achieve high accuracy with maximum cost effectiveness. Lastly, the experimental data successfully validate the test and the method of design and analysis.

The terahertz (THz) frequency domain, located at the frontier of radio and light, is the last unexplored region of the electromagnetic spectrum. As technology becomes available, THz systems are finding applications to fields ranging all the way from astronomical and atmospheric remote sensing to space telecommunications, medical imaging, and security. In Astronomy the THz and far infrared (IR) portion of the electromagnetic spectrum (lambda = 300 to 10 mum) may hold the answers to countless questions regarding the origin and evolution of the Universe, galaxy, star and planet formation. Over the past decade, advances in telescope and detector technology have for the first time made this regime available to astronomers. Near THz frequencies, metallic hollow waveguide structures become so small, (typically much less than a millimeter), that conventional machining becomes extremely difficult, and in many cases, nearly impossible. Laser induced, micro-chemical etching is a promising new technology that can be used to fabricate three dimensional structures many millimeters across with micrometer accuracy. Laser micromachining of silicon possesses a significant edge over more conventional techniques. It does not require the use of masks and is not confined to crystal planes. A non-contact process, it eliminates tool wear and vibration problems associated with classical milling machines. At the University of Arizona we have constructed the first such laser micromachining system optimized for the fabrication of THz and far IR waveguide and quasi-optical components. The system can machine structures up to 50 mm in diameter, down to a few microns accuracy in a few minutes and with a remarkable surface finish. A variety of THz devices have been fabricated using this technique, their design, fabrication, assembly and theoretical performance is described in the chapters that follow.

Photoluminescence from direct-bandgap semiconductor quantum wells after non-resonant excitation is predominantly observed at energetic position of the 1s exciton resonance. The time evolution of the photoluminescence is generally interpreted as direct monitor of an excitonic population; a rise of the signal is interpreted as a buildup and the decrease as decay of the excitonic population. Recent microscopic calculations, however, have shown that even without an incoherent excitonic population, pure plasma decay yields photoluminescence peaked at the is exciton resonance. Experimental time-resolved photoluminescence spectra are taken across a large region of the parameter space of carrier density and lattice temperature. They are compared to the expected thermal equilibrium spectra, calculated from nonlinear absorption measurements taken under identical conditions. Under none of the experimentally explored parameters is the is emission as bright as expected for thermal equilibrium. To distinguish excitonic and plasma contributions, the deviations from thermal equilibrium at the is exciton resonance are then analyzed using a microscopic calculation. The dipole moment is adjusted to reproduce the excitonic binding energy and oscillator strength of the samples under investigation. The carrier densities and carrier temperatures are determined experimentally; no free fit parameters are necessary. The differences between experimental values and pure plasma calculation are explained with the presence of an incoherent excitonic population. Although at first the emission spectra under all conditions do not vary significantly, a more detailed analysis reveals that the sources of the photoluminescence can be either predominantly excitonic or plasma. For low temperatures and low densities the excitonic emission is extremely sensitive to even minute exciton populations making it possible to extract a phase diagram for incoherent excitonic populations. The maximum contribution of bright excitons is found at intermediate densities and low lattice temperatures; the absolute number of bright excitons is tiny, less than 0.04% of the total carrier density. However, it is not possible to determine the total number of bright and dark exciton by using photoluminescence.

Optical fibers have revolutionized telecommunications. Much of the success of optical fiber lies in its near-ideal properties: low transmission loss, high optical damage threshold, and low optical nonlinearity. The photosensitivity of an optical fiber was accidentally discovered by Hill, et al. in 1978. However, the technological advances made in the field of photosensitive optical fibers are relatively recent. This fascinating technology of photosensitive fiber is based on the principle of a simple in-line all-fiber optical filter. It has been shown that the transmission spectrum of a fiber Bragg grating can be tailored by incorporating multiple phase-shift regions during the fabrication process. Phase shifts open up ultra narrowband transmission windows inside the stop band of the Bragg grating. As a specific application, this research is focused on applying this technology in future space-based water vapor DIfferential Absorption LIDAR (DIAL) systems to improve the performance of space-based LIDAR systems by rejecting the reflected solar background. The primary goal of this research effort was to demonstrate the feasibility of using ultra narrow band fiber optic Bragg grating filters for atmospheric water vapor measurements. Fiber Bragg gratings were fabricated such that two transmission filter peaks occurred and were tunable, one peak at a 946 nm water vapor absorption line and another peak at a region of no absorption. Both transmission peaks were in the middle of a 2.66-nm stop band. Experimental demonstration of both pressure and temperature tuning was achieved and characterization of the performance of several custom-made optical fiber Bragg grating filters was made. To our knowledge these are the first optical fiber gratings made in this frequency range and for this application. The bandwidth and efficiency of these filters were measured and then these measurements were compared with theoretical calculations using a piecewise matrix form of the coupled-mode equation. Finally, an ultra narrow band water vapor DIAL filter was characterized having two pass bands less than 8 pm and peak transmissions greater than 80 percent. Such fiber optic filters are now ready for integrating into space-based water vapor LIDAR systems. More broadly, these filters have the characteristics that will revolutionized satellite remote-sensing.

Designing an adaptive optics (AO) system for extremely large telescopes (ELT's) will present new optical engineering challenges. Several of these challenges are addressed in this work, including first-order design of multi-conjugate adaptive optics (MCAO) systems, pyramid wavefront sensors (PWFS's), and laser guide star (LGS) spot elongation. MCAO systems need to be designed in consideration of various constraints, including deformable mirror size and correction height. The y,ȳ method of first-order optical design is a graphical technique that uses a plot with marginal and chief ray heights as coordinates; the optical system is represented as a segmented line. This method is shown to be a powerful tool in designing MCAO systems. From these analyses, important conclusions about configurations are derived. PWFS's, which offer an alternative to Shack-Hartmann (SH) wavefront sensors (WFS's), are envisioned as the workhorse of layer-oriented adaptive optics. Current approaches use a 4-faceted glass pyramid to create a WFS analogous to a quad-cell SH WFS. PWFS's and SH WFS's are compared and some newly-considered similarities and PWFS advantages are presented. Techniques to extend PWFS's are offered: First, PWFS's can be extended to more pixels in the image by tiling pyramids contiguously. Second, pyramids, which are difficult to manufacture, can be replaced by less expensive lenslet arrays. An approach is outlined to convert existing SH WFS's to PWFS's for easy evaluation of PWFS's. Also, a demonstration of PWFS's in sensing varying amounts of an aberration is presented. For ELT's, the finite altitude and finite thickness of LGS's means that the LGS will appear elongated from the viewpoint of subapertures not directly under the telescope. Two techniques for dealing with LGS spot elongation in SH WFS's are presented. One method assumes that the laser will be pulsed and uses a segmented micro-electromechanical system (MEMS) to track the LGS light subaperture by subaperture as the light is returned from the upward-propagating laser pulse. A second method can be used if the laser is not pulsed. A lenslet array is described which creates "pixels" which are aligned with the axes of the elongated spot of each subaperture, without requiring special charge-coupled devices (CCD's).