论文标题
各向异性在跨TMD单层的非线性谐波生成中的作用
Role of Anisotropy in Nonlinear Harmonic Generation Across TMD Monolayers
论文作者
论文摘要
最近的技术允许过渡金属二核苷（TMD）单层生长并充分表征。他们的非线性光学响应特别令人感兴趣，为未来的纳米摄影设备和技术提供了许多有希望的机会。载体的分散体进行了三角杆，导致低洼状态的各向异性费米表面。在本文中，通过考虑在$ \ mathbf {k} \ cdot \ mathbf {p} $中将这种变形对非线性谐波生成的影响。通过与强烈和超短的光脉冲相互作用时，通过精确求解载体的自由载体动力学，我们以非扰动的方式预测光生的电流并研究其谐波组成。我们发现在二次模型和立方模型中非线性电流的频率和振幅调制。此外，我们证明了各向异性诱导的高阶谐波强度的调制和谐波交叉的存在，具体取决于入射光极化。本文介绍的方法可以应用于任何一般有效的两波段模型，并提供了识别光输出中电子特征签名的途径。
Recent techniques have allowed transition metal dichalcogenides (TMD) monolayers to be grown and adequately characterised. Of particular interest, their nonlinear optical response presents many promising opportunities for future nanophotonic devices and technology. The dispersion of the carriers is trigonally-warped, leading to an anisotropic Fermi surface for low-lying states. In this paper, the effects of such a deformation on the nonlinear harmonic generation are studied by considering a tight-binding model expanded up to third order in $\mathbf{k} \cdot \mathbf{p}$. By solving exactly the free-carrier dynamics of the carriers when interacting with intense and ultrashort pulses of light, we predict the photogenerated current in a nonperturbative way and study its harmonic composition. We find frequency and amplitude modulation of the nonlinear current in quadratic and cubic models. Furthermore, we demonstrate anisotropy-induced modulation of the intensity of higher-order harmonics and the existence of harmonic crossovers, depending on the incident light polarisation. The methodology presented in this paper may be applied to any general effective two-band model and offer a pathway to identify signatures of electronic features in optical output.
