Spectral red-shift of solid high-order harmonic generation combining a fundamental field and a terahertz field

Abstract

Abstract High-order harmonic generation (HHG) from a solid by combining a fundamental field and a terahertz field is investigated by solving the time-dependent Schrödinger equation. The numerical results illustrate that the red-shift from odd harmonics is more obvious in the combined field than the fundamental field. We have also investigated solid HHG with different relative phases. We find that the HHG spectra exhibit a larger red-shift from odd harmonics for the relative phase φ = 0 and the red-shift from odd harmonics is gradually weakened by increasing the relative phase. For the relative phase φ = π, the red-shift of solid HHG disappears and only odd harmonic order can be observed. The time-dependent population imaging picture is used to illustrate the physical mechanism of the red-shift in solid HHG.