Fig. 1. Schematic of evolution of electric field amplitude and wavevector during laser beam propagation.

Fig. 2. The angle of individual rays at the exit of the zone with high beam intensity where induced refraction is large computed for laser beam propagation through air (normal conditions) assuming Gaussian temporal shape of the laser pulse with duration and a Gaussian spatial beam profile with the beam radius on level in the waist, , shown as a function of dimensionless laser radius, , for different moments of dimensionless time, , (negative – before the pulse): (a) total radiated energy per pulse (maximum irradiance ); (b) total radiated energy per pulse (maximum irradiance ). All computational results correspond to the laser wavelength .