Search academic texts

Information × Registration Number 0214U006039, 0113U004536 , R & D reports Title Femtosecond filamentation of vortex and bessel beams in condensed media. popup.stage_title Head Kadan Viktor Mykolaiovych, Доктор фізико-математичних наук Registration Date 05-02-2014 Organization Institute of physics NASU popup.description2 Objects of research: femtosecond laser filaments in nonlinear dielectric media. Objective: reduction of the duration of femtosecond laser pulses, study of the spatio-temporal dynamics of filamentation of femtosecond Bessel beams and generation of femtosecond optical vortices with different topological charges. Methods of research: autocorrelation method of duration measurement of femtosecond laser pulses, photoluminescent microscopy. Femtosecond laser pulse of 150 fs duration is compressed to 65 fs in crystalline quartz. Stability of the compressing material to the processes of laser damage is increased from 1 minute to 30-40 minutes. Spatial structure of periodic unsteady filaments excited by Bessel beam is studied for the first time. Two periodic filaments are detected, one of which is oriented along the propagation axis, and the second one consists of the fragments, which are oriented at a small angle to the optical axis. Period L of the longitudinal modulation of the filaments is determined by longitudinal interference of conical excitation wave and coherent plane wave. The period is described by the formula L = ? / n (1 - cos?). Angular direction of generation of white continuum is defined by the direction of the observed structure of the filaments. Experimental setup is produced for generation of optical vortices with topological charge l = 1 and l = 2 and vortex nature of the generated beams is proved. Filamentation of powerful femtosecond optical vortex with topological charge l = 2 in sapphire is experimentally studied. A method of controlling the azimuthal position of the filaments by changing the phase difference between the mutually coherent coaxial optical vortex and vortex-free plane reference wave is proposed and implemented. Product Description popup.authors Блонський Іван Васильович Головченко Олена Миколаївна Кадан Віктор Миколайович Коренюк Петро Іванович popup.nrat_date 2020-04-02 Close