Conical versus Gaussian terahertz emission from two-color laser-induced air plasma filaments.
Opt Lett
; 45(7): 2132-2135, 2020 Apr 01.
Article
em En
| MEDLINE
| ID: mdl-32236087
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}} $TEM00 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.
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01-internacional
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MEDLINE
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En
Ano de publicação:
2020
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Article