Longitudinal compression of short laser pulses in air

We have performed laboratory experiments to study long distance propagation of large bandwidth ultrashort laser pulses in air. Initial pulse length, frequency chirping, and laser pulse energy were varied where the maximum propagation distance was up to 105 m. We have demonstrated the compression of initially negatively chirped low intensity laser pulses due to the linear group velocity dispersion of air. The characteristics of the compressed pulse such as pulse duration and spectral chirping were found to be significantly affected by the laser pulse intensity, with higher intensities corresponding to longer minimum compressed pulse duration. (C) 2004 American Institute of Physics.