Zurrón-Cifuentes Óscar, Boyero-García Roberto, Hernández-García Carlos, Picón Antonio, Plaja Luis
Opt Express. 2019 Mar 4;27(5):7776-7786. doi: 10.1364/OE.27.007776.
High harmonic generation in atomic or molecular targets stands as a robust mechanism to produce coherent ultrashort pulses with controllable polarization in the extreme-ultraviolet. However, the production of elliptically or circularly-polarized harmonics is not straightforward, demanding complex combinations of elliptically or circularly-polarized drivers, or the use of molecular alignment techniques. Nevertheless, recent studies show the feasibility of high-harmonic generation in solids. In contrast with atoms and molecules, solids are high-density targets and therefore more efficient radiation sources. Among solid targets, 2D materials are of special interest due to their particular electronic structure, which conveys special optical properties. In this paper, we present theoretical calculations that demonstrate an extraordinary complex light-spin conversion in single-layer graphene irradiated at non perturbative intensities. Linearly-polarized drivings result in the emission of elliptically-polarized harmonics, and elliptically-polarized drivings may result in linearly-polarized or ellipticity-reversed harmonics. In addition, we demonstrate the ultrafast temporal modulation of the harmonic ellipticity.
在原子或分子靶中产生高次谐波是一种强大的机制，可用于在极紫外波段产生具有可控偏振的相干超短脉冲。然而，产生椭圆偏振或圆偏振谐波并非易事，需要椭圆偏振或圆偏振驱动的复杂组合，或者使用分子取向技术。尽管如此，最近的研究表明在固体中产生高次谐波是可行的。与原子和分子不同，固体是高密度靶，因此是更高效的辐射源。在固体靶中，二维材料因其特殊的电子结构而具有特殊的光学性质，因而备受关注。在本文中，我们给出了理论计算结果，证明了在非微扰强度下辐照的单层石墨烯中存在一种非同寻常的复杂光 - 自旋转换。线偏振驱动会导致椭圆偏振谐波的发射，而椭圆偏振驱动可能会导致线偏振或椭圆率反转的谐波。此外，我们还展示了谐波椭圆率的超快时间调制。
