Energy exchange between two noncollinear filament-forming laser pulses in air

Energy exchange between two filament-forming pulses with initially free chirp in air was experimentally studied. It occurs because of the change of delayed nonlinear refractive index, which slightly chirps the incident filament-forming laser pulses. Accompanying energy exchange process, spectral characteristics of output laser pulses shows dramatic blueshift and supercontinuum generation. Nonlinear absorptive effect introduces an inbalance between energy exchange at the negative delays and that at the positive delays, and affects the energy exchange efficiency. These results may provide a more comprehensive understanding of energy exchange process between filament-forming laser pulses.