Conical versus Gaussian terahertz emission from two-color laser-induced air plasma filaments

In this Letter, we demonstrate that the far-field terahertz (THz) beam generated from a Ti:Sapphire two-color laser-induced filament can exhibit a conical or Gaussian distribution, depending on the filtering experimental conditions. Using both an incoherent Golay cell detector and a two-dimensional...

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Bibliographic Details
Published in:Optics letters 2020-04, Vol.45 (7), p.2132-2135
Main Authors: Sørensen, Christian Buhl, Guiramand, Léo, Degert, Jérôme, Tondusson, Marc, Skovsen, Esben, Freysz, Eric, Abraham, Emmanuel
Format: Article
Language:English
Subjects:
Air plasma
Color
Emission
Engineering Sciences
Far fields
Filaments
Gaussian beams (optics)
Gaussian distribution
Laser beams
Lasers
Normal distribution
Optics
Photonic
Physics
Sapphire
Silicon
Spatial distribution
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Summary:In this Letter, we demonstrate that the far-field terahertz (THz) beam generated from a Ti:Sapphire two-color laser-induced filament can exhibit a conical or Gaussian distribution, depending on the filtering experimental conditions. Using both an incoherent Golay cell detector and a two-dimensional coherent electro-optic detection covering the 0.2-2.6 THz spectral range, in our experimental conditions, we provide evidence that the conical emission is due to photo-induced carriers in the silicon filter, typically used to block the remaining pump laser light. Moreover, the low-frequency THz beam retrieves an almost $ {{\rm TEM}_{00}} $TEM Gaussian spatial distribution when the silicon filter is preceded by a large bandgap ceramic filter, which stops the pump beam, thus preventing the carrier generation in the silicon filter.
ISSN:0146-9592
1539-4794
DOI:10.1364/OL.390112