Abstract

It has been shown in 3 + 1 dimensional Kerr-non- linearity self-focusing models, that group velocity dispersion is responsible for the temporal pulse-splitting of ultrashort pulses during propagation.¹ Previous experiments have demonstrated pulse splitting due to the Kerr nonlinearity for short pulse propagation in bulk² or gaseous media. ^3,4 However, studies in gaseous media are often in a focused geometry, or use pressurized gaseous media.^3,5 This experiment elucidates the relationship between pulse splitting and spot-size change and does not use any optic to initiate self- focusing.⁵ We find pulse splitting occurs at a distance merely 0.7x the diffraction length and occurs before spatial collapse to a filament. In addition, multiple pulse splitting is also observed. Peak fluence information from the beam-profile is monitored, indicating nonlinear loss mechanisms. We believe this is the first data on multiple pulse-splitting events in air.

© 2001 Optical Society of America