Publications

The spatial, spectral and temporal properties of self-focusing 798-nm 100-fs pulses in air were experimentally measured. It was measured using high-resolution, single-shot techniques at a set propagation distance of 10.91 m. The data were taken over an extended energy range and can thus be used to test the validity of physical models. The experimental results show that significant spatial, spectral and temporal changes occur at intensities lower than than those required for strong ionization of air.

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UV filaments in air have been examined on the basis of the diameter and length of the filament, the generation of new spectral components, and the ionization by multiphoton processes. There have been numerous observations of filaments at 800 nm. The general perception is that, above a critical power, the beam focuses because nonlinear self-lensing overcomes diffraction. The self-focusing proceeds until an opposing higher order nonlinearity forms a stable balance.