Pulse shortening due to filamentation in transparent medium

Spatial contraction of high-peak-power femtosecond pulse in air leads to its simultaneous shortening in time domain. Numerical simulations in the slowly evolving wave approximation show that the full width at half maximum duration of the 45 fs 800 nm pulse becomes ∼8 fs as soon as the intensity reaches the ionization threshold. At this propagation distance the compressed pulse accumulates maximum of its energy that is ∼4% of the initial pulse energy. Higher than the second orders of material dispersion decrease the maximum possible energy achieved in the compressed pulse.