Modifying angular and polarization selection rules of high-order harmonics by controlling electron trajectories in k-space
Modifying angular and polarization selection rules of high-order harmonics by controlling electron trajectories in k-space
复制标题
DOI：
10.1038/s41467-020-16875-5
复制
发表时间：
2020-06
影响因子：
16.6
通讯作者：
Yasuyuki Sanari;T. Otobe;Y. Kanemitsu;H. Hirori
中科院分区：
文献类型：
--
作者：
Yasuyuki Sanari;T. Otobe;Y. Kanemitsu;H. Hirori
强激光脉冲产生方面的最新进展使得固体中的电子能够加速到远离能带边缘的区域。由于非抛物线区域中的激光驱动载流子可以产生非线性电流，因此定制的激光场可以控制高次谐波 (HH) 的光学特性。迄今为止，对激光引起的非线性光学现象的研究主要集中在线性或椭圆偏振场引起的简单电子运动上。然而，更复杂的轨迹对于新型光电器件的开发可能很重要。在这里，我们表明，在与强主场（ω1）正交的方向上施加的弱激光场（光频率为ω2）将块体GaSe的某些HH强度分量增强了100倍。实验和计算之间的良好一致性表明，电子轨迹的操纵可以打破加速电子所感受到的电子态的反转对称性，并导致HH混频过程的选择规则的修改。由于我们对 ω1 和 ω2 使用非整数倍数，我们发现 HH 的产生构成了一种超快控制光偏振和光开关的新方法。
Recent advances in generation of strong laser pulses have enabled the acceleration of electrons in solids into regions far away from the band edge. Because nonlinear currents can be generated by laser-driven carriers in the non-parabolic region, tailored laser fields may allow control of optical properties of high-order harmonics (HHs). So far, investigations on laser-induced nonlinear optical phenomena have focused on the simple electron motion induced by linearly or elliptically polarized fields. However, more complex trajectories can be important for development of novel optoelectronic devices. Here, we show that a weak laser field (optical frequency isω2) applied in a direction orthogonal to a strong main field (ω1) enhances certain HH intensity components of bulk GaSe by a factor of 100. Good agreement between the experiments and calculations shows that manipulation of the electron trajectory allows breaking inversion symmetry of the electronic states felt by the accelerated electrons and leading to a modification of selection rules for frequency-mixing processes of HHs. Owing to our usage of non-integer multiples forω1andω2, it is found that the generation of HHs constitutes a novel way of ultrafast control of light polarization and optical switching.