Filamentation length of ultrashort laser pulse in presence of aerosol layer

Filamentation behavior of femtosecond laser pulses in the air in presence of aerosol on the optical path is simulated numerically on basis of (3D + 1)-dimensional nonlinear Schrödinger equation. The effect of a localized attenuating layer modeling an aerosol medium, on spatial extension and evolution of the light filament is investigated. For the first time, it is shown that filamentation length depends not only on the optical depth of the aerosol layer and pulse peak power, but also on aerosol location on the propagation path and its spatial extension along the beam. The length of the filament is maximal if the nonlinear focus of the beam is located behind the aerosol layer rather than before it.