Generation of broadband THz beams with azimuthally modulated phase and intensity by femtosecond laser pulses in air plasma
Paper i proceeding, 2019

We report efficient generation of the broadband terahertz (THz) radiation by bichromatic femtosecond laser pulses with flat phase fronts or with a phase singularity focused in air. As a pump source, the fundamental and second harmonic radiations of a femtosecond Ti:sapphire laser were used. While the fundamental laser beam had Gaussian intensity distribution and a flat phase front, the second harmonic beam had either flat or helical phase front forming an optical vortex. In both cases the angular spectra of THz radiation and azimuthal phase distributions of THz beams were investigated. It was found that when both the fundamental and second harmonic laser pulses had Gaussian profiles, the resulting THz radiation was generated as an axially symmetric cone with a flat phase front. However, when the Gaussian second harmonic beam was replaced by the one with optical singularity, the intensity and the phase of generated THz cone became modulated along the azimuthal angle. The spectrum of generated THz pulses spanned up to 50 THz in both cases. Our theoretical analysis based on the photocurrent model was in good agreement with the experimental data.

Terahertz radiation

Laser created air plasma

Femtosecond laser pulses

Optical vortex


Virgilijus Vaičaitis

Vilniaus universitetas

Maksym Ivanov

Vilniaus universitetas

Illia Thiele

Chalmers, Fysik, Subatomär fysik och plasmafysik

Danas Buožius

Vilniaus universitetas

Ivona Juchnevičiūtė

Vilniaus universitetas

Stefan Skupin

Université de Lyon

Luc Bergé

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

Proceedings of SPIE - The International Society for Optical Engineering

0277786X (ISSN) 1996756X (eISSN)

Vol. 11370 443-444
9781510635128 (ISBN)

Ultrafast Optics XII 2019
Bol, Croatia,


Acceleratorfysik och instrumentering

Atom- och molekylfysik och optik

Annan fysik

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