Pulse chirping and ionization of O-2 molecules for the filamentation of femtosecond laser pulses in air

摘要

We examine two analytical models describing the photoionization of O-2 molecules in both tunnel and multiphoton regimes. Applying these models to the nonlinear propagation of chirped laser beams in the atmosphere, we demonstrate how chirp phases can be used as a tool to monitor the self-guiding range of femtosecond filaments or even to shorten the pulse duration. The good agreement between simulations and experimental measurements validates our numerical code for ultrashort-pulse propagation in air. (c) 2006 Optical Society of America.