论文标题
线性偏振激光脉冲控制谷地
Valley control by linearly polarized laser pulses
论文作者
论文摘要
“ valleytronics”领域的基础是圆形光线与山谷自由度的螺旋性的耦合，这仍然是唯一已知的光明形式，表现出这种显着效果。在这里，我们表明，在飞秒时间尺度上，山谷耦合是一种更一般的效果。我们发现，两次分离的线性极化脉冲几乎可以完全控制山谷激发，脉冲时间差和极化向量作为山谷控制的关键参数出现。与支撑圆形极化光的效果的浆果曲率相反，我们证明了不同的相结构驱动了这种效果，并且在每个线性脉冲中获得的激发获得了山谷区分域的较小阶段，涉及线性光的极化角度。在单个线性脉冲中不重要，对于成对的脉冲，这些脉冲可以建设性地和破坏性干扰。采用最新的时间依赖性密度函数理论，我们表明效果对真实材料中电荷动力学的复杂性具有牢固的效果，其效果是过渡金属二进制基因源的示例。
Underpinning the field of "valleytronics" is the coupling of the helicity of circularly polarized light to the valley degree of freedom, and this remains the only known lightform to exhibit this remarkable effect. Here we show that on femtosecond time scales valley coupling is a much more general effect. We find that two time separated linearly polarized pulses allow almost complete control over valley excitation, with the pulse time difference and polarization vectors emerging as key parameters for valley control. In contrast to the Berry curvature that underpins the effect for circularly polarized light, we demonstrate that a different phase structure drives this effect, with excitations during each linear pulse acquiring a valley discriminating phase involving the polarisation angle of linear light. Unimportant in a single linear pulse, for pairs of pulses these can constructively and destructively interfere. Employing state-of-the-art time dependent density function theory, we show that the effect is robust to the complexities of charge dynamics in a real material with the example of a transitional metal dichalcogenide.
