标题： 由动态布洛赫振荡引起的椭圆度依赖性转变 显示英文标题

标题： Ellipticity dependence transition induced by dynamical Bloch oscillations

摘要： 高次谐波生成（HHG）对激光椭圆率的依赖性通过修改的ZnO模型进行研究。 在相对较弱场的驱动下，我们定性地再现了在纤锌矿ZnO的HHG实验中观察到的椭圆率依赖性。 当增加场强时，HHG表现出异常的椭圆率依赖性，类似于在单晶MgO中实验观察到的情况。 借助半经典分析，发现导致椭圆率依赖性变化的关键机制是动态布洛赫振荡与各向异性能带结构之间的相互作用。 动态布洛赫振荡提供了额外的量子路径，这些路径对椭圆率不那么敏感。 各向异性能带结构使得具有有限椭圆率的驱动脉冲能够将电子对驱动到具有更大带隙的能带位置，从而扩展了谐波截止。 这两种效应的结合导致了异常的椭圆率依赖性。 结果揭示了动态布洛赫振荡对于体相ZnO的HHG椭圆率依赖性的重要性。 显示英文摘要

摘要： The dependence of high-harmonic generation (HHG) on laser ellipticity is investigated using a modified ZnO model. In the driving of relatively weak field, we reproduce qualitatively the ellipticity dependence as observed in the HHG experiment of wurtzite ZnO. When increasing the field strength, the HHG shows an anomalous ellipticity dependence, similar to that observed experimentally in the single-crystal MgO. With the help of a semiclassical analysis, it is found that the key mechanism inducing the change of ellipticity dependence is the interplay between the dynamical Bloch oscillation and the anisotropic band structure. The dynamical Bloch oscillation contributes additional quantum paths, which are less sensitive to ellipticity. The anisotropic band-structure make the driving pulse with finite ellipticity be able to drive the pairs to the band positions with larger gap, which extends the harmonic cutoff. The combination of these two effects leads to the anomalous ellipticity dependence. The result reveals the importance of dynamical Bloch oscillations for the ellipticity dependence of HHG from bulk ZnO.