Intensity modulated terahertz vortex wave generation in air plasma by two-color femtosecond laser pulses
Artikel i vetenskaplig tidskrift, 2019

We investigate the generation of broadband terahertz (THz) pulses with phase singularity from air plasmas created by fundamental and second harmonic laser pulses. We show that when the second harmonic beam carries a vortex charge, the THz beam acquires a vortex structure as well. A generic feature of this THz vortex is that the intensity is modulated along the azimuthal angle, which can be attributed to the spatially varying relative phase difference between the two pump harmonics. Fully space- and time-resolved numerical simulations reveal that transverse instabilities of the pump further affect the emitted THz field along nonlinear propagation, which may produce additional singularities resulting in a rich vortex structure. The predicted intensity modulation is experimentally demonstrated with a thermal camera, in excellent agreement with simulation results. The presence of phase singularities in the experiment is revealed by astigmatic transformation of the beam using a cylindrical mirror. (c) 2019 Optical Society of America

Femtosecond lasers

Cylindrical mirror

Two-color femtosecond laser pulse

Terahertz waves

Harmonic analysis


Maksym Ivanov

Vilniaus universitetas

Illia Thiele

Chalmers, Fysik, Subatomär fysik och plasmafysik

Luc Berge

Le Commissariat à l’Énergie Atomique et aux Énergies Alternatives (CEA)

Stefan Skupin

Université de Lyon

Danas Buozius

Vilniaus universitetas

Virgilijus Vaicaitis

Vilniaus universitetas

Optics Letters

0146-9592 (ISSN) 1539-4794 (eISSN)

Vol. 44 15 3889-3892


Atom- och molekylfysik och optik

Annan fysik

Fusion, plasma och rymdfysik





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