Femtosecond nonlinear optical phenomena in bulk solids and gas-filled hollow waveguides

This thesis highlights work done in the field of femtosecond nonlinear optics. It covers two main topics: laser-induced breakdown of dielectrics and ultrashort-pulse propagation in a hollow-waveguide.; We investigate the use of infrared femtosecond laser pulses to induce highly localized refractive index changes in fused-silica glasses. We characterize the magnitude of the change as a function of exposure and measure index changes in pure fused silica and boron-doped silica as large as 3 × 10 −3 and 5 × 10−3, respectively. The potential of this technique for writing three-dimensional photonic structures in bulk glasses is demonstrated by the fabrication of a Y-coupler within a sample of pure fused-silica.; We present new measurements of laser-induced damage threshold fluences in both fused silica and sapphire. We compare surface damage thresholds with bulk thresholds and find that for bulk thresholds nonlinear propagation effects, such as self-focusing, play an important role in determining the damage threshold energy.; We then present a theoretical investigation of the self-focusing dynamics of femtosecond pulses in a hollow waveguide. We show that transverse effects play an important role even for pulses significantly below the critical power for self-focusing in free space and that excitation of higher-order modes of the waveguide results in the spreading of the pulse in time.; Taking advantage of the ability of hollow waveguides to accommodate high-peak power pulses, we present work that demonstrates an improvement in the pulse contrast of microjoule-energy femtosecond laser pulses by several orders of magnitude using nonlinear ellipse rotation in a gas-filled hollow waveguide. This scheme offers a number of advantages over competing techniques, including a high degree of tunability which allows for a broad range of input-pulse parameters, higher throughput, greater stability, and an output pulse with high spatial quality that is compressible to a quarter of the original temporal width.