High-order harmonic generation (HHG) from a solid by combining a fundamental field and a terahertz field is investigated by solving the time-dependent Schrdinger 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.

通过求解与时间有关的薛定equation方程，研究了通过结合基波场和太赫兹场从固体产生高次谐波（HHG）。数值结果表明，在合成场中，奇次谐波的红移比基本场更明显。我们还研究了具有不同相对相的固体HHG。我们发现，HHG光谱在相对相位φ  = 0时显示出更大的相对于奇次谐波的红移，并且随着相对相位的增加，奇异谐波的红移逐渐减弱。对于相对相位φ  =  π，固体HHG的红移消失，只能观察到奇次谐波。随时间变化的人口成像图片用于说明固体HHG中红移的物理机制。