FILAMENTATION OF LASER PULSES AT HIGH GAS PRESSURE

The report presents the results of our studies of the effect of the pressure of a gas medium in an optical cell on the characteristics of femtosecond laser radiation propagating in the filamentation regime. It is shown that under conditions of high pressure and sharp geometric focusing of radiation, its Kerr self-focusing is realized, which transforms from the regime of single filamentation to the regime of generation of a multiple of intense filaments – post-filaments with gas pressure increasing. It has been defined for the first time that the pulse spectrum is asymmetrically widened mainly to the long-wavelength region with an increase of the sharpness of the initial beam focusing. In addition, as the gas pressure in the optical cell increases, the average size of the intense light post-filaments formed inside the beam decreases and may be fractions of a millimeter.