In strong laser fields, the electron density in solids can show up tidal motions caused by the laser ``pulling'' on the electrons, which forms an electron density tide (EDT). However, the strong field processes in solids are always explained by the single-active-electron (SAE) model and the fluctuation of background electrons is neglected previously. Here, we demonstrate the strong field induced EDT effect and propose a model for revealing its role in high harmoinc generation (HHG) from solids. We show that the EDT effect induces an additional polarization current beyond the SAE approximation. It gives a new mechanism for HHG and leads to new anisotropic structures, which are experimentally observed with MgO. Our experiment indicates that the EDT effect becomes more obvious with increasing the laser intensity. Our work establishes the bridge between the HHG and the microscopic EDT in solids induced by the strong laser field, which paves the way to probe the ultrafast electron dynamics.
Unambiguous discrimination of high harmonic generation mechanisms in solids
Max Born Institute（马克斯·玻恩研究所）；Joint Attosecond Science Laboratory, National Research Council of Canada（联合阿秒科学实验室，加拿大国家研究委员会）；University of Ottawa（渥太华大学）；Institute for Physics, University of Rostock（罗斯托克大学物理研究所）；Department of Physics, Humboldt University（柏林洪堡大学物理系）；Blackett Laboratory, Imperial College London（帝国理工学院布莱克特实验室）
Symmetry breaking by quantum light in solid-state high-harmonic generation
ICFO—Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology（ICFO-光子科学研究所，巴塞罗那科技研究院）；Atominstitut, Technische Universität Wien（原子物理研究所，维也纳工业大学）；Department of Physics and Astronomy, University College London（伦敦大学学院物理与天文系）；Department of Materials Science and Engineering, Pohang University of Science and Technology（浦项科技大学材料科学与工程系）；Departamento de Física, Área de Física, Universidad de Panamá（巴拿马大学物理系）；Sistema Nacional de Investigación de Panamá（巴拿马国家研究系统）；Centro de Investigación con Técnicas Nucleares, Universidad de Panamá（巴拿马大学核技术研究中心）；Parque Científico y Tecnológico, Universidad Autónoma de Chiriquí（奇里基自治大学科技园）；Eastern Institute of Technology（东方理工学院）
Twisting harmonics: Transfer of orbital angular momentum in solid-state high-harmonic generation
ELI-ALPS, ELI-Hu Non-Profit Ltd.（极端光基础设施激光平台，匈牙利非营利有限公司）；Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena（耶拿弗里德里希·席勒大学理论物理研究所）；Laboratoire Photonique Numérique et Nanosciences (LP2N), UMR 5298, CNRS-IOGS-Université Bordeaux（数字光子学与纳米科学实验室（LP2N），UMR 5298，法国国家科学研究中心-高等光学学院-波尔多大学）；Centro de Investigaciones en Óptica, A.C.（光学研究中心）；School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology（上海理工大学光电信息与计算机工程学院）；Zhejiang Key Laboratory of 3D Micro/Nano Fabrication and Characterization, Department of Electronic and Information Engineering, School of Engineering, Westlake University（西湖大学工学院电子与信息工程系三维微纳制造与表征浙江省重点实验室）；International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM2), Hiroshima University（广岛大学结型手性超材料可持续国际研究所（WPI-SKCM2））；Helmholtz-Institut Jena（耶拿亥姆霍兹研究所）；GSI Helmholtzzentrum für Schwerionenforschung GmbH（德国重离子研究中心亥姆霍兹有限公司）
Field-driven helicity in solid-state high-harmonic generation
Universidad de Panamá（巴拿马大学）；Pohang University of Science and Technology（浦项科技大学）；Friedrich-Schiller-Universität Jena（耶拿弗里德里希·席勒大学）；Eastern Institute of Technology（东方理工学院）；Sistema Nacional de Investigación de Panamá（巴拿马国家研究系统）；Centro de Investigación con Técnicas Nucleares, Universidad de Panamá（巴拿马大学核技术研究中心）；Universidad Autónoma de Chiriquí（奇里基自治大学）
Sensing coherent phonon dynamics in solids with delayed even harmonics
Max-Planck-Institut für Physik komplexer Systeme（马克斯·普朗克复杂系统物理研究所）；School of Nuclear Science and Technology, Lanzhou University（兰州大学核科学与技术学院）；School of Physics, Ningxia University（宁夏大学物理学院）
Sculpting ultrafast mid-infrared light for solid-state high harmonic generation
Eastern Institute of Technology（东方理工学院）；ELI-ALPS, ELI-Hu Non-Profit Ltd.（极强光激光科学研究所有限公司）；Laboratoire Photonique Numérique et Nanosciences (LP2N), UMR 5298, CNRS-IOGS-Université Bordeaux（波尔多大学光子学与纳米科学实验室）；Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena（耶拿大学理论物理研究所）；Centro de Investigaciones en Óptica, A.C.（光学研究中心）；School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology（上海理工大学光电信息与计算机工程学院）；Zhejiang Key Laboratory of 3D Micro/Nano Fabrication and Characterization, Department of Electronic and Information Engineering, School of Engineering, Westlake University（西湖大学工学院电子与信息工程系三维微纳加工与表征浙江省重点实验室）；Helmholtz-Institut Jena（耶拿亥姆霍兹研究所）；GSI Helmholtzzentrum für Schwerionenforschung GmbH（达姆施塔特重离子研究中心）
Programmable high-harmonic emission in solids through photon pathways
Advanced Research Center for Nanolithography（先进纳米光刻研究中心）；Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy（马克斯·玻恩非线性光学与超短脉冲光谱研究所）；Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas（马德里材料科学研究所，西班牙高等科学研究委员会）；Department of Physics and Astronomy, and LaserLaB, Vrije Universiteit（自由大学物理与天文系及激光实验室）
