The far-field angular distributions of high-order harmonics of a 1054-nm laser, with orders ranging from the lower teens to the upper thirties, have been measured in thin, low-density Ar, Kr, and Xe targets. The 1.25times-diffraction-limited, 1.4-ps-duration, Gaussian laser pulses were focused to intensities ranging from 3 X 10' to 3 X 10' W/cm, using f/70 optics. A gas target localized the gas...

Title of Document: STUDY OF THE FEMTOSECOND DYNAMICS AND SPECTROSCOPY OF LASER IONIZED PLASMAS. JJennifer Anne Elle, Doctor of Philosophy, 2015 Directed By: Professor Howard Milchberg Department of Physics Ultra-short laser pulses are used to ionize gas in different configurations and study the plasma and ionization dynamics. The variation in non-linear index of refraction as a function of time...

Residual hydrogen (H2) gas in the analysis chamber of an atom probe instrument limits the ability to measure H concentration in metals and alloys. Measuring H concentration would permit quantification of important physical phenomena, such as hydrogen embrittlement, corrosion, hydrogen trapping, and grain boundary segregation. Increased insight into the behavior of residual H2 gas on the specime...

The use of high intensity ultrashort pulsed laser radiation to produce optical breakdown is an important approach for the surgical treatment of intraocular structures. We have investigated the transient properties of Nd:YAG laser induced breakdown in a saline model using time-resolved spectroscopic techniques. Spatially resolved pump and probe techniques are applied to study the dynamic behavio...

The power supply of flash lamp-pumped a Nd: YAG solid-state laser basically consists of a trigger circuit which initiate the ionization of the gas into the lamp, a simmer circuit that keeps the ionized gas with a low-level dc current and a main discharge circuit where a storage capacitor is discharged into a flash lamp to pump the Nd:YAG laser. The impedance of the flash lamp presents a nonline...

We report on improvements made on our previously introduced technique of cavity-enhanced Raman spectroscopy (CERS) with optical feedback cw-diode lasers in the gas phase, including a new mode-matching procedure which keeps the laser in resonance with the optical cavity without inducing long-term frequency shifts of the laser, and using a new CCD camera with improved noise performance. With 10 m...

Generation of high harmonics is the only available way to obtain coherent extreme ultraviolet (EUV) and soft X-ray radiation in laboratory conditions. We present a system for high harmonics generation and study of its parameters. Capillary waveguide filled with Ar gas is used to convert the pumping laser radiation from a Ti:Sapphire mode-locked femtosecond laser system. In the capillary the las...

The dissertation, titled \Genetic Algorithms Applied to Nonlinear and Complex Do-mains", describes and then applies a new class of powerful search algorithms (GAs) to certain domains. GAs are capable of solving complex and nonlinear problems where many parameters interact to produce a ``nal' result such as the optimization of the laser pulse in the interaction of an atom with an intense laser e...

Vibrational Raman spectroscopy is performed in the gas phase using a femtosecond laser pulse undergoing filamentation as an impulsive excitation source. The molecular coherence induced by the filamentary pulse is subsequently probed using a narrowband, sub-picosecond laser pulse to produce Raman spectra of gas phase species in a few tens of milliseconds (~10 laser shots). Pulse shortening with ...

short): Hollow-core Optical Fiber Gas LASer (HOFGLAS) have been created, and explored in pulsed mode with C2H2 and HCN gas inside the hollow core of a kagome structured photonic crystal fiber, and nearideal efficiencies were realized for wavelengths near 1.5 μm (pump, 1 ns-pulses) and 3 μm (lasing). Improved fiber loss is realized near 3 μm to <1 dB/m. In addition, a pulsed CO2 waveguide (silve...