ИСТИНА

New properties of mid-infrared pulses interaction with the atmosphere under normal conditions were researched by the workgroup from united laboratory of Russian Quantum Center and laboratory of photonics and nonlinear spectroscopy of Lomonosov Moscow State University. The unique laser system was used for these aims to generate powerful ultrafast mid-infrared pulses. This system consists of a solid-state ytterbium oscillator, a regenerative amplifier, a three- stage optical parametric amplifier, and a three-stage optical parametric chirped- pulse amplifier. New specific features of high-power laser pulses filamentation in the atmospheric air were demonstrated with using the above-mentioned laser system which generates sub-100- fs 3.9-µm pulses with energy about 30 mJ. The phenomenon of the supercontinuum spanning over 4.7 octaves in a wavelength range from 250 to 6500 nm was accomplished by the high order harmonic generation with order up to the 15 th . The angle-resolved spectra of converted pump radiation were researched in the conditions of filamentation and high order harmonics generation in the atmosphere. These spectra revealed the complex off-axial beam dynamics. It established that this dynamics was defined by strong scattering and by blue shift of the signal field and it’s components because of ionization-induced refraction. Provided researches have significant meaning for high-field physics, standoff detection, molecular vibrational spectroscopy and generation of extremely short pulses, based on the new scenarios of powerful coherent radiation interaction with the matter.