The generation and propagation of sub-picosecond, high-peak-power, laser pulses.

In this thesis, various aspects of high-peak-power laser pulses are discussed, including the generation of pulses from a compact directly diode-pumped chirped-pulse-amplification (CPA) laser system, and the self-channeling of high-peak-power laser pulses in air. With the maturation of CPA laser systems, the amplification of laser pulses to the terawatt level is becoming common. With these pulses, even air acts as a nonlinear media with novel nonlinear effects seen only after a few meters of propagation. Due to self-focusing and self-phase modulation, an initially collimated high-peak-power pulse is shown to spatially collapse into a high-intensity regime, limited in spot size through the generation of a low-density plasma. Through an interplay of self-focusing, natural diffraction, and refraction from the generated plasma, a self-channel can form, leading to the propagation of a high-intensity pulse for distances of over 30 meters, limited by losses experienced during propagation. In this work, various experiments were performed to characterize the pulse during propagation in the self-channel, includes measurements on the spatial profile, spectral content, and energy contained in the high intensity core. Further, the ability to control the onset of filamentation was shown by changing the initial pulse duration through adjustments of the pulse chirp. Also, results of a numerical model which solves the nonlinear Schrodinger equation including ionization are shown. In the subsequent part of this thesis, the development of a compact, directly diode-pumped CPA laser system is described. This system produced high-peak-power (100 MW), 450-fs pulses at repetition rates in excess of 1 kHz. This section proceeds from a discussion of semiconductor laser diodes to the development of a diode-pumped Nd:glass modelocked oscillator (characterized by a high-dynamic-range autocorrelator) and regenerative amplifier. As well, based on a rate equation analysis, novel lifetime effects from cw-pumped regenerative amplifiers are shown. Finally, a discussion of different methods used to achieve better mode-matching from a multimode pump beam is presented. These include the use of highly doped gain media, the use of a lossless spatial filter to reduce the $M\sp2$ value of the diode beam, and matching of the cavity mode to the pump beam through use of an elliptical cavity mode.Ph.D.Applied SciencesElectrical engineeringOpticsPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/130430/2/9732041.pd