We studied the high-order harmonic generation (HHG) from 2D solid materials in circularly and bichromatic circularly polarized laser fields numerically by simulating the dynamics of single-active-electron processes in 2D periodic potentials. Contrary to the absence of HHG in the atomic case, circular HHGs below the bandgap with different helicities are produced from intraband transitions in solids with C₄ symmetry driven by circularly polarized lasers. Harmonics above the bandgap are elliptically polarized due to the interband transitions. High-order elliptically polarized harmonics can be generated efficiently by both co-rotating and counter-rotating bicircular mid-infrared lasers. The cutoff energy, ellipticity, phase, and intensity of the harmonics can be tuned by the control of the relative phase difference between the 1ω and 2ω fields in bicircularly polarized lasers, which can be utilized as an ultrafast optical tool to image the structure of solids.

中文翻译：

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在圆和双色圆偏振激光场中由2D周期电势产生高次谐波

通过模拟二维周期电势中单活性电子过程的动力学，我们对圆形和双色圆偏振激光领域中二维固体材料的高阶谐波产生（HHG）进行了数值研究。与原子序中没有HHG的情况相反，带隙以下具有不同螺旋度的圆形HHG是由C ₄固体中的带内跃迁产生的由圆偏振激光器驱动的对称性。由于带间跃迁，带隙上方的谐波被椭圆极化。通过同时旋转和反向旋转双圆中红外激光器，可以有效地生成高阶椭圆偏振谐波。谐波的截止能量，椭圆率，相位和强度可以通过在1之间的相对相位差的控制来调整ω和2 ω在bicircularly偏振激光器字段，其可以被用作一个超高速光学工具，以图像的结构固体。