Femtosecond laser pulse energy transfer induced by plasma grating due to filament interaction in air

We experimentally demonstrate the formation of a thin plasma grating lasted for several tens of picosecond induced by the strong interaction between two noncollinear femtosecond filaments in air. A time-delayed second-harmonic pulse propagating along one of the incident filaments is coupled and nonlinearly diffracted by the thin plasma grating, leading to an energy transfer to the other noncollinearly crossed femtosecond filament. The dependences of the plasma grating on the intensity ratios and relative polarizations between the input pulses are investigated.