title: Wavelength scaling of terahertz generation by gas ionization.
abstract: Low-frequency currents induced by ultrashort laser-driven ionization can emit extremely broadband, single-cycle terahertz pulses. We present a model that predicts a strong wavelength dependence of the THz emission in good agreement with our experimental study. This reveals that the combined effects of plasma currents rising proportionally to the square of the pump wavelength and wavelength-dependent focusing conditions lead to 30 times higher THz emission at 1800 nm compared to an 800 nm wavelength. Unrivaled single-cycle electric field strengths of 4.4  MV/cm are achieved with this compact table-top setup.
authors.affiliation: INRS-EMT, 1650 Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2, Canada. clerici@emt.inrs.ca
authors.forename: Matteo
authors.initials: M
authors.lastname: Clerici
authors.forename: Marco
authors.initials: M
authors.lastname: Peccianti
authors.forename: Bruno E
authors.initials: BE
authors.lastname: Schmidt
authors.forename: Lucia
authors.initials: L
authors.lastname: Caspani
authors.forename: Mostafa
authors.initials: M
authors.lastname: Shalaby
authors.forename: Mathieu
authors.initials: M
authors.lastname: Giguère
authors.forename: Antonio
authors.initials: A
authors.lastname: Lotti
authors.forename: Arnaud
authors.initials: A
authors.lastname: Couairon
authors.forename: François
authors.initials: F
authors.lastname: Légaré
authors.forename: Tsuneyuki
authors.initials: T
authors.lastname: Ozaki
authors.forename: Daniele
authors.initials: D
authors.lastname: Faccio
authors.forename: Roberto
authors.initials: R
authors.lastname: Morandotti