K.S. Khorkov - Research Engineer, Department «Physics and Applied Mathematics», Vladimir State University named after A.&N. Stoletovs. E-mail: freeod@mail.ru D.A. Kochuev - Research Engineer, Department «Physics and Applied Mathematics», Vladimir State University named after A.&N. Stoletovs. E-mail: _b_@mail.ru D.V. Abramov - Ph. D. (Phys.-Math.), Associate Professor, Department «Physics and Applied Mathematics», Vladimir State University named after A.&N. Stoletovs. E-mail: awraam@mail.ru A.D. Kornilova - Student, Department «Physics and Applied Mathematics», Vladimir State University named after A.&N. Stoletovs. E-mail: anyto4ka18@mail.ru S.M. Arakelyan - Dr. Sc. (Phys.-Math.), Professor, Department «Physics and Applied Mathematics», Vladimir State University named after A.&N. Stoletovs. E-mail: arak@vlsu.ru R.V. Chkalov - Student, Department «Physics and Applied Mathematics», Vladimir State University named after A.&N. Stoletovs. E-mail: j.larenax@gmail.com V.G. Prokoshev - Dr. Sc. (Phys.-Math.), Professor, Department «Physics and Applied Mathematics», Vladimir State University named after A.&N. Stoletovs. E-mail: prokoshev_vg@vlsu.ru

In article described the results of experimental studies of the spectrum broadening femtosecond laser radiation under filamentation and the formation of conical emission. The basic experimental schemes for registration of change of the intensity distribution in the cross section of the laser beam are presented. Investigation of the occurrence mechanism of multiple filamentation in transparent media is aimed at ensuring spatial regularization of the entire array of filaments. In the experimental schemes we used femtosecond Ti:Sapphire laser system (company «Avesta-Project», Troitsk, Russia) having the following parameters: wavelength 800 nm, radiation pulse duration 50 fs, pulse repetition frequency 1 kHz, pulse energy 1 mJ. The initial profile of the laser beam has a Gaussian distribution with slight random fluctuations. The intensity at the cross section of the laser beam is redistributed after it passes through the glass plate. This is a consequence of the formation of the filaments inside the sample and also their further dissemination. Registered plasma channels of filaments are stable in time and are disseminated on long distances without changing of relative position in the cross section of the laser beam. This phenomenon allows a controlled exposure of the filaments of laser radiation on materials. The research results revealed the formation of two spatially structured flows of optical radiation at the passage of the femtosecond laser beam through the transparent glass plate: filaments and conical emission. These results can find applications in microphotonics or micromachining of materials, including for direct writing of waveguide structures.

 

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