Filamentation of chirped mid-IR pulses in ambient air in the vicinity of zero dispersion

Variation of the sign of dispersion in air in the vicinity of 3.6 pm [1] makes propagation and filamentation of mid-IR pulses extremely sensitive to the chirp, which allows to take control over the temporal pulse splitting, spectral broadening, energy losses and spatial profile. Here we report on filamentation of 30-mJ, 3.9-pm pulses produced by a hybrid OPA/OPCPA system [2]. Filamentation in ambient air is assisted by loose 7-m focusing and controlled by adjusting the chirp of the output of the OPCPA system.