Infrared interferometric systems using a CO₂ laser operating at a wavelength of 10.6 μm have been investigated. The purpose of infrared interferometry is to test (1) optical components required for high energy laser systems such as infrared transmitting materials and diamond-turned metal mirrors, (2) unpolished rough surface optics during the early stages of fabrication, and (3) deep aspherics and other optics of nonconventional surface figures. The physical principles behind longer wavelength interferometry are as follows. First, the specular component of scattered light increases with increasing wavelength for randomly rough surfaces. Second, the aspheric departure from the best fit reference sphere (in units of probing wavelength) is reduced. This reduced sensitivity gives us a manageable number of fringes in the interferogram of deep aspherics. Specific systems developed in this work are the infrared laser unequal path interferometer (IRLUPI), the IRLUPI with infrared computer generated hologram (IRCGH), the infrared common path interferometers such as the infrared point diffraction interferometer (IRPDI), and the infrared scatterplate interferometer (IRSPI). The above interferometers produce interferograms of equal optical path difference (OPD). Other types of common path interferometers which provide interferograms of differential OPD (or slope) are also developed. They are the infrared lateral shearing interferometers (IRLSI); a germanium plane parallel plate, the Ronchi ruling, and the double grating lateral shearing interferometer. A pyroelectric vidicon (PEV) has been employed as an AC infrared detector with proper intensity modulation techniques. Chopping, panning, and phase variation of the interferogram modulate the interference pattern effectively for various types of interferometers. Germanium and zinc selenide optics are used for lenses and beamsplitters. A He-Ne gas laser is installed parallel to the CO₂ beam for the ease of initial alignment. Many test interferograms are shown using each interferometer. The statistical analysis and experimental verification of the relationship between fringe contrast and rms surface roughness enabled us to have noncontact measurement of surface roughness interferometrically. This result was used for a series of tests for the unpolished large diameter off-axis parabolic mirror during the preliminary fabrication stage. Some interesting topics are included for future investigation to fulfill the growing demand for versatility in interferometry.

Extremely compact high-power fiber lasers operating at eye-safe telecom wavelength of 1.5 μm have been achieved by systematic experimental studies. Heavily Er3+-Yb3+-codoped phosphate glasses have been chosen as the host glass for our fibers and 1.5 μm lasers have been realized when pumped with 975 nm laser diodes.The first short-length cladding-pumped fiber laser with watt-level CW output power has been demonstrated by an 11-cm-long doped step-index phosphate fiber. Without active cooling, 1.5 W output power at 1535 nm has been obtained.Thermoelectric cooler has been used for heavily doped phosphate step-index fibers. A dual-end-pumped actively cooled fiber laser has generated more than 11 W CW output power at 1535 nm from an 11.9 cm long active fiber. A fully 3-dimensional thermal analysis has been performed to calculate the internal temperature distribution of the short-length fiber laser and the simulated results have been experimentally verified.Phosphate glass microstructured optical fibers (MOFs) with large active cores have been fabricated. The first demonstrated short phosphate MOF laser has generated > 3 W single-mode CW output power from an 11-cm-long fiber. The impacts of depressed-core-index and annealing upon MOF's modal property have been systematically investigated. Extremely compact high-power fiber laser is demonstrated by a heavily doped MOF laser and > 4.5 W single-mode CW output power is delivered from a 3.5 cm long fiber. Finally, a high-power single-frequency fiber laser is realized by splicing a FBG with a 3.8 cm long MOF, which achieves > 2 W single-frequency output power.

A novel method of simulating edge-emitting semiconductor lasers in a non-equilibrium steady-state is developed. The simulation is based on a non-equilibrium Green's function (NEGF) method. The Dyson equation (central equation of this method) is derived and written in a basis suitable for numerical implementation. The electron-photon self-energy is derived form scratch for the case of the edge-emitting laser. Other interactions present in the simulation are phenomenological scattering and scattering due to longitudinal optical phonons. This microscopic approach significantly reduce the number of phenomenological parameters needed to simulate laser. As an example, the theory is applied to analyze quantum well laser with the effective mass Hamiltonian. The major laser characteristics such as modal gain, threshold gain, carrier and current densities are determined.

Ulm, Univ., Diss., 2007.

Thesis (M.S.) in Mechanical Engineering--University of Maine, 2008. / Includes vita. Includes bibliographical references (leaves 141-145).

Zugl.: Ulm, Universiẗat, Diss., 2008.

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 170-175).

Thesis (doctoral)--Mainz, 1982.

Berlin, Techn. Univ., Diss., 2005. / Computerdatei im Fernzugriff.

Hamburg, Univ., Diss., 2001. / Computerdatei im Fernzugriff.