title: Transformation of terahertz spectra emitted from dual-frequency femtosecond pulse interaction in gases.
abstract: We demonstrate that the two basic physical mechanisms of terahertz (THz) generation in a femtosecond filament, namely, the free electron photocurrent and the nonlinear polarization of neutrals, can be identified through the spectral analysis of THz radiation. The contribution from the photocurrent peaks at the units of THz, while the neutrals yield the peak at the tens of THz. We suggest the practical implementation of such spectral analysis by varying the initial transform-limited laser pulse duration.
authors.affiliation: Department of Physics and International Laser Center, Lomonosov Moscow State University, Moscow 119923, Russia.
authors.forename: A V
authors.initials: AV
authors.lastname: Borodin
authors.forename: N A
authors.initials: NA
authors.lastname: Panov
authors.forename: O G
authors.initials: OG
authors.lastname: Kosareva
authors.forename: V A
authors.initials: VA
authors.lastname: Andreeva
authors.forename: M N
authors.initials: MN
authors.lastname: Esaulkov
authors.forename: V A
authors.initials: VA
authors.lastname: Makarov
authors.forename: A P
authors.initials: AP
authors.lastname: Shkurinov
authors.forename: S L
authors.initials: SL
authors.lastname: Chin
authors.forename: X-C
authors.initials: XC
authors.lastname: Zhang