Feature

Unraveling the Mysteries of Intense Femtosecond Pulse Propagation

Scott A. Diddams, Hilary K. Eaton, Amelia G. Van Engen, and Tracy S. Clement, JILA, Univ. of Colorado, and NIST, Boulder, CO; Alex A. Zozulya, Dept. of Physics, Worcester Polytechnical Institute, Worcester, MA.

Propagation of electromagnetic pulses is of fundamental importance in pure and applied science, and the recent development of sources of intense femtosecond laser pulses has added many interesting twists to this long-standing problem. The broad spectral band-widths, high peak powers, and 4-D nature of femtosecond fields give rise to complicated linear and nonlinear dynamics that have posed significant challenges to researchers. A few years ago, it was observed that in contrast to a continuous beam of light, a femtosecond pulse having the same peak power does not collapse to a singularity under the influence of self-focusing in a nonlinear medium. Instead, the original pulse splits temporally into two pulses of lower power. However, the details of this splitting process remained unclear, and furthermore, it was unknown whether the newly split pulses would in turn undergo a secondary splitting.