Figure 6
Dynamics of a high-power ultrashort mid-IR pulse in a filament.
(a, b) The maps of the field intensity calculated (a) as a function of the radial coordinate r and the retarded time τ and (b) as a function of the radial coordinate r and the wavelength for z = 80 cm. (c) The spectrum of a high-peak-power mid-infrared driver experiences broadening and gets dressed with odd-order harmonics as the pulse propagates through the atmospheric air, inducing a filament. (d–f) The radial distribution of spectral components across the beam at z = 60 cm (d), 70 cm (e) and 80 cm (f) visualizes a strong plasma-induced blue shift of harmonics on the periphery of the beam. Dashed ellipses are used as contours of harmonics generated in the central part of the beam and on the beam periphery.
