González de Alaiza, PedroBabushkin, IharBergé, LucSkupin, StephanCabrera Granado, EduardoKöhler, ChristianMörgner, UweHusakou, Anton V.Herrmann, Jens2023-06-182023-06-182015-05-060031-900710.1103/PhysRevLett.114.183901https://hdl.handle.net/20.500.14352/23092© 2015 American Physical SocietyBroadband ultrashort terahertz (THz) pulses can be produced using plasma generation in a noble gas ionized by femtosecond two-color pulses. Here we demonstrate that, by using multiple-frequency laser pulses, one can obtain a waveform which optimizes the free electron trajectories in such a way that they acquire the largest drift velocity. This allows us to increase the THz conversion efficiency to 2%, an unprecedented performance for THz generation in gases. In addition to the analytical study of THz generation using a local current model, we perform comprehensive 3D simulations accounting for propagation effects which confirm this prediction. Our results show that THz conversion via tunnel ionization can be greatly improved with well-designed multicolor pulses.engjournal articlehttps://doi.org/10.1103/PhysRevLett.114.183901http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.183901open access537.533.3535.374532.59ElectronsTeraherz wavesLaserMultiple frequencyIonizationInert gasesOptoelectrónicaÓptica física, óptica cuánticaLáseres2209.19 Óptica física2209.10 Láseres