Fig. 3.
Validity of the semiperturbative model. (A) Dependence of the harmonic yield on driving laser intensity. (B) Harmonic yield vs. 400 nm pump intensity for the noncollinear HHG simulation in Eq. 13 (black solid lines) and experimental data taken from ref. 26 for different wave-mixing signals . The system, noncollinear geometry, and laser parameters are the same as in ref. 26. In the simulations, only HOMO orbital and continuum states are included, and the transition dipole moments are taken from ref. 27. The horizontal axis of simulation data is divided by a factor of 10 (see Results and Discussion), which does not affect the scaling law. (C and D) Comparison of the high-order harmonic spectra from the sum of the three lowest-order responses, e.g., zeroth-, first-, and second-order responses (red line) and the numerical solution of Eq. 2 (black line) for three different laser intensities, separately.