摘要：SummaryThe terahertz radiation from ultraintense laser-produced plasmas has aroused increasing attention recently as a promising approach toward strong terahertz sources. Here, we present the highly efficient production of millijoule-level terahertz pulses, from the rear side of a metal foil irradiated by a 10-TW femtosecond laser pulse. By characterizing the terahertz and electron emission in combination with particle-in-cell simulations, the physical reasons behind the efficient terahertz generation are discussed. The resulting focused terahertz electric field strength reaches over 2 GV/m, which is justified by experiments on terahertz strong-field-driven nonlinearity in semiconductors.Graphical abstractDisplay OmittedHighlights•Ultraintense laser-foil interactions generate a 2.1-mJ strong terahertz pulse•Nearly 1% generation efficiency originates from optimized laser-plasma conditions•2-GV/m high THz fields induce absorption bleaching and impact ionizationLaser; Radiation physics; Surface science
