Neutral atom contribution in the strong-field harmonic generation

摘要

Summary form only given. High-order harmonic generation in the strong-field limit has successfully been modeled by a quasistatic picture based on the tunneling ionization of an atom, acceleration of the electron in the continuum, and recombination to the atomic ground state. We report experimental results strongly suggesting that the harmonics are predominantly produced by the nonlinear response of neutral atoms even in the tunneling regime.