Ultrashort Infrared 2.5-11 Micron Pulses: Spatiotemporal Profiles and Absolute Nonlinear Response of Air Constituents

We measure the detailed spatiotemporal profiles of femtosecond laser pulses in the infrared wavelength range of δ = 2.5-11 μm and the absolute nonlinear response of major air constituents (N₂,O₂, and Ar) over this range. The spatiotemporal measurements reveal wavelength-dependent pulse front tilt and temporal stretching in the infrared pulses.