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Femtosecond filamentation dynamics of synthesized coronary profile laser beam in air: numerical simulations

Multiple filamentation in air of high-power ultrashort laser radiation with transverse intensity profile resembling a “corona-beam” (CB) composed by incoherent combining of several annularly distributed independent top-hat sub-beams is theoretically considered. Through the numerical solution of time-averaged nonlinear Schrodinger equation, we study the spatio-angular dynamics of synthesized near infrared CB along the optical path by varying the number and peak power of the beamlets. The evident advances in the multiple-filamentation region manipulating of synthesized CB are demonstrated. Particularly, by adjusting the number and aperture of the constituting sub-beams it makes possible to significantly delay the filamentation onset distance and increase the filamentation length in air.