Polarization-Resolved Study of High Harmonics from Bulk Semiconductors
Polarization-Resolved Study of High Harmonics from Bulk Semiconductors
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DOI：
10.1103/physrevlett.120.243903
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发表时间：
2018-06-12
影响因子：
8.6
通讯作者：
Itatani, Jiro
中科院分区：
文献类型：
--
作者：
Kaneshima, Keisuke;Shinohara, Yasushi;Itatani, Jiro
利用线偏振中红外激光脉冲研究了硒化镓高次谐波的偏振特性。在高电场下，出现了奇次谐波的垂直偏振分量，这在低电场下不存在，且不能用微扰非线性光学来解释。建立了一个二维单带模型，表明固体能带的各向异性曲率（在布里渊区外部显著）诱导了垂直奇次谐波的产生。这个模型通过三维量子力学模拟得到了验证，该模拟重现了奇次谐波的取向依赖性。量子力学模拟还揭示出奇次谐波和偶次谐波分别主要由带内电流和带间极化产生。这些实验和理论证明清楚地表明了固体的能带结构和奇次谐波的偏振特性之间的紧密联系。
The polarization property of high harmonics from gallium selenide is investigated using linearly polarized midinfrared laser pulses. With a high electric field, the perpendicular polarization component of the odd harmonics emerges, which is not present with a low electric field and cannot be explained by the perturbative nonlinear optics. A two-dimensional single-band model is developed to show that the anisotropic curvature of an energy band of solids, which is pronounced in an outer part of the Brillouin zone, induces the generation of the perpendicular odd harmonics. This model is validated by three-dimensional quantum mechanical simulations, which reproduce the orientation dependence of the odd-order harmonics. The quantum mechanical simulations also reveal that the odd- and even-order harmonics are produced predominantly by the intraband current and interband polarization, respectively. These experimental and theoretical demonstrations clearly show a strong link between the band structure of a solid and the polarization property of the odd-order harmonics.