Filamentation Nonlinear Optics: Third Harmonic Generation and Four-Wave-Mixing Inside a Filament

Abstract

Aközbek et al. (2002a) discovered a new phenomenon called self-phase locking both experimentally and theoretically during third harmonic generation inside a filament in air. During the filamentation of an ultrashort and intense laser pulse in air, the generated third harmonic pulse inside the filament propagates with the fundamental at the same group velocity due to nonlinear intensity dependent cross interaction between the two pulses. The cross interaction through the Kerr effect generates what the authors (Aközbek et al., 2002a) called two-color filament at which the relative phase between the fundamental and the third harmonic pulses is self-locked together despite the group velocity dispersion between the fundamental and the third harmonic.