title: Two-color laser-plasma generation of terahertz radiation using a frequency-tunable half harmonic of a femtosecond pulse.
abstract: We investigate for the first time, both experimentally and theoretically, low-frequency terahertz (THz) emission from the ambient air ionized by a two-color femtosecond laser pulse containing, besides the fundamental-frequency main field, a weak additional field tunable near the frequency of the half harmonic. By controlling the mutual polarization and the powers of the main and additional fields, we determine the dependences of the THz power and polarization on the parameters of the two-color pulse. We also discover the resonantlike dependence of the THz yield on the frequency detuning of the additional field. The analytical formulas obtained using the model of the free-electron residual current density give an excellent agreement with the experimental results.
authors.affiliation: Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia and University of Nizhny Novgorod, Nizhny Novgorod 603950, Russia.
authors.forename: N V
authors.initials: NV
authors.lastname: Vvedenskii
authors.affiliation: Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia.
authors.forename: A I
authors.initials: AI
authors.lastname: Korytin
authors.affiliation: Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia and University of Nizhny Novgorod, Nizhny Novgorod 603950, Russia.
authors.forename: V A
authors.initials: VA
authors.lastname: Kostin
authors.affiliation: Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia.
authors.forename: A A
authors.initials: AA
authors.lastname: Murzanev
authors.affiliation: Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia and University of Nizhny Novgorod, Nizhny Novgorod 603950, Russia.
authors.forename: A A
authors.initials: AA
authors.lastname: Silaev
authors.affiliation: Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia.
authors.forename: A N
authors.initials: AN
authors.lastname: Stepanov