1
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Mushtaq A, Journigan T, Turkowski V, Siebenaller R, Jeff DA, Truong TC, Noor MY, Khatri D, Lantigua C, Harrison K, Khondaker SI, Rowe E, Goldstein JT, Susner MA, Chowdhury E, Chini M. Efficient High-Order Harmonic Generation from the van der Waals Layered Crystal Copper Indium Thiophosphate. J Am Chem Soc 2024. [PMID: 39172082 DOI: 10.1021/jacs.4c04515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
Layered metal thio- and selenophosphates (MTPs) are a family of van der Waals gapped materials that exhibit a multitude of functionalities in terms of magnetic, ferroelectric, and optical properties. Despite the recent progress in terms of understanding the material properties of these compounds, the potential of MTPs as a material class yet needs further scrutiny, especially in terms of nonlinear optical properties. Recent reports of efficient low-order harmonic generation and extremely high third-order nonlinear optical properties in MTPs suggest the potential application of these materials in integrated nanophotonics. In this article, we investigate the high-order nonlinear response of bulk and exfoliated thin-film crystals of copper indium thiophosphate (CIPS) to intense mid-infrared fields through experimental and computational studies of high-order harmonic generation (HHG). From a driving laser source with a 3.2 μm wavelength, we generate odd and even harmonics up to the 10th order, exceeding the bandgap of the material. We note conversion efficiencies as high as 10-7 measured for the fifth and seventh harmonics and observe that the harmonic intensities follow a power law scaling with the driving laser intensity, suggesting a perturbative nonlinear optical origin of the observed harmonics for both bulk and thin flakes. Furthermore, first-principles calculations suggest that the generation of the highest harmonic orders results from electron-electron interactions, suggesting a correlation-mediated enhancement of the high-order optical nonlinearity.
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Affiliation(s)
- Aamir Mushtaq
- Department of Physics, University of Central Florida, Orlando, Florida 32816, United States
| | - Troie Journigan
- Department of Physics, University of Central Florida, Orlando, Florida 32816, United States
| | - Volodymyr Turkowski
- Department of Physics, University of Central Florida, Orlando, Florida 32816, United States
| | - Ryan Siebenaller
- Department of Materials Science and Engineering, The Ohio State University, 140W 19th Avenue, Columbus, Ohio 43210, United States
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Dylan A Jeff
- Department of Physics, University of Central Florida, Orlando, Florida 32816, United States
- NanoScience Technology Center, University of Central Florida, Orlando, Florida 32826, United States
| | - Tran-Chau Truong
- Department of Physics, University of Central Florida, Orlando, Florida 32816, United States
| | - Mohamed Yaseen Noor
- Department of Materials Science and Engineering, The Ohio State University, 140W 19th Avenue, Columbus, Ohio 43210, United States
| | - Dipendra Khatri
- Department of Physics, University of Central Florida, Orlando, Florida 32816, United States
| | - Christopher Lantigua
- Department of Physics, University of Central Florida, Orlando, Florida 32816, United States
| | - Kamal Harrison
- Department of Physics, University of Central Florida, Orlando, Florida 32816, United States
- NanoScience Technology Center, University of Central Florida, Orlando, Florida 32826, United States
| | - Saiful I Khondaker
- Department of Physics, University of Central Florida, Orlando, Florida 32816, United States
- NanoScience Technology Center, University of Central Florida, Orlando, Florida 32826, United States
| | - Emmanuel Rowe
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
- National Research Council, Washington, District of Columbia 20001, United States
| | - Jonathan T Goldstein
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Michael A Susner
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Enam Chowdhury
- Department of Materials Science and Engineering, The Ohio State University, 140W 19th Avenue, Columbus, Ohio 43210, United States
| | - Michael Chini
- Department of Physics, University of Central Florida, Orlando, Florida 32816, United States
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2
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Nagai K, Okamoto T, Shinohara Y, Sanada H, Oguri K. High-harmonic spin-orbit angular momentum generation in crystalline solids preserving multiscale dynamical symmetry. SCIENCE ADVANCES 2024; 10:eado7315. [PMID: 39093966 PMCID: PMC11296342 DOI: 10.1126/sciadv.ado7315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 06/18/2024] [Indexed: 08/04/2024]
Abstract
Symmetries essentially provide conservation rules in nonlinear light-matter interactions and facilitate control and understanding of photon conversion processes or electron dynamics. Since anisotropic solids have rich symmetries, they are strong candidates for controlling both optical micro- and macroscale structures, namely, spin angular momentum (circular polarization) and orbital angular momentum (spiral wavefront), respectively. Here, we show structured high-harmonic generation linked to the anisotropic symmetry of a solid. By strategically preserving a dynamical symmetry arising from the spin-orbit interaction of light, we generate multiple orbital angular momentum states in high-order harmonics. The experimental results exhibit the total angular momentum conservation rule of light even in the extreme nonlinear region, which is evidence that the mechanism originates from a dynamical symmetry. Our study provides a deeper understanding of multiscale nonlinear optical phenomena and a general guideline for using electronic structures to control structured light, such as through Floquet engineering.
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Affiliation(s)
- Kohei Nagai
- NTT Basic Research Laboratories, NTT Corporation, 3-1, Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan
| | - Takuya Okamoto
- NTT Basic Research Laboratories, NTT Corporation, 3-1, Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan
| | - Yasushi Shinohara
- NTT Basic Research Laboratories, NTT Corporation, 3-1, Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan
- NTT Research Center for Theoretical Quantum Information, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198, Japan
| | - Haruki Sanada
- NTT Basic Research Laboratories, NTT Corporation, 3-1, Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan
| | - Katsuya Oguri
- NTT Basic Research Laboratories, NTT Corporation, 3-1, Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan
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3
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Wang Y, Liu Y, Zhang J, Liu X, Jiang P, Xiao J, Zhang L, Yang H, Peng LY, Liu Y, Gong Q, Wu C. High-Order Harmonic Generation in Photoexcited Three-Dimensional Dirac Semimetals. J Phys Chem Lett 2024:8101-8107. [PMID: 39087866 DOI: 10.1021/acs.jpclett.4c01522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2024]
Abstract
High-order harmonic generation (HHG) in condensed matter is highly important for potential applications in various fields, such as materials characterization, all-optical switches, and coherent light source generation. Linking HHG to the properties or dynamic processes of materials is essential for realizing these applications. Here, a bridge has been built between HHG and the transient properties of materials through the engineering of interband polarization in a photoexcited three-dimensional Dirac semimetal (3D-DSM). It has been found that HHG can be efficiently manipulated by the electronic relaxation dynamics of 3D-DSM on an ultrafast time scale of several hundred femtoseconds. Furthermore, time-resolved HHG (tr-HHG) has been demonstrated to be a powerful spectroscopy method for tracking electron relaxation dynamics, enabling the identification of electron thermalization and electron-phonon coupling processes and the quantitative extraction of electron-phonon coupling strength. This demonstration provides insights into the active control of HHG and measurements of the electron dynamics.
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Affiliation(s)
- Yang Wang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Yu Liu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Jianing Zhang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Xiulan Liu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Pengzuo Jiang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Jingying Xiao
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Linfeng Zhang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
| | - Hong Yang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu 226010, China
| | - Liang-You Peng
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu 226010, China
| | - Yunquan Liu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu 226010, China
| | - Qihuang Gong
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu 226010, China
| | - Chengyin Wu
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu 226010, China
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4
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van Essen PJ, Nie Z, de Keijzer B, Kraus PM. Toward Complete All-Optical Intensity Modulation of High-Harmonic Generation from Solids. ACS PHOTONICS 2024; 11:1832-1843. [PMID: 38766500 PMCID: PMC11100285 DOI: 10.1021/acsphotonics.4c00156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 04/11/2024] [Accepted: 04/11/2024] [Indexed: 05/22/2024]
Abstract
Optical modulation of high-harmonics generation in solids enables the detection of material properties, such as the band structure, and promising new applications, such as super-resolution imaging in semiconductors. Various recent studies have shown optical modulation of high-harmonics generation in solids, in particular, suppression of high-harmonics generation has been observed by synchronized or delayed multipulse sequences. Here we provide an overview of the underlying mechanisms attributed to this suppression and provide a perspective on the challenges and opportunities regarding these mechanisms. All-optical control of high-harmonic generation allows for femtosecond, and in the future possibly subfemtosecond, switching, which has numerous possible applications: These range from super-resolution microscopy to nanoscale controlled chemistry and highly tunable nonlinear light sources.
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Affiliation(s)
- Pieter J. van Essen
- Advanced
Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
| | - Zhonghui Nie
- Advanced
Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
| | - Brian de Keijzer
- Advanced
Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
| | - Peter M. Kraus
- Advanced
Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
- Department
of Physics and Astronomy, and LaserLaB, Vrije Universiteit, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands
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5
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Takeda KS, Uchida K, Nagai K, Kusaba S, Takahashi S, Tanaka K. Ultrafast Electron-Electron Scattering in Metallic Phase of 2H-NbSe_{2} Probed by High Harmonic Generation. PHYSICAL REVIEW LETTERS 2024; 132:186901. [PMID: 38759158 DOI: 10.1103/physrevlett.132.186901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 12/31/2023] [Accepted: 03/19/2024] [Indexed: 05/19/2024]
Abstract
Electron-electron scattering on the order of a few to tens of femtoseconds plays a crucial role in the ultrafast electron dynamics of conventional metals. When mid-infrared light is used for driving and the period of light field is comparable to the scattering time in metals, unique light-driven states and nonlinear optical responses associated with the scattering process are expected to occur. Here, we use high-harmonics spectroscopy to investigate the effect of electron-electron scattering on the electron dynamics in thin film 2H-NbSe_{2} driven by a mid-infrared field. We observed odd-order high harmonics up to 9th order as well as a broadband emission from hot electrons in the energy range from 1.5 to 4.0 eV. The electron-electron scattering time in 2H-NbSe_{2} was estimated from the broadband emission to be almost the same as the period of the mid-infrared light field. A comparison between experimental results and a numerical calculation reveals that competition and cooperation between the driving and scattering enhances the nonperturbative behavior of high harmonics in metals, causing a highly nonequilibrium electronic state corresponding to several thousand Kelvin.
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Affiliation(s)
- K S Takeda
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - K Uchida
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - K Nagai
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - S Kusaba
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - S Takahashi
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - K Tanaka
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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6
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Nie Z, Guery L, Molinero EB, Juergens P, van den Hooven TJ, Wang Y, Jimenez Galan A, Planken PCM, Silva REF, Kraus PM. Following the Nonthermal Phase Transition in Niobium Dioxide by Time-Resolved Harmonic Spectroscopy. PHYSICAL REVIEW LETTERS 2023; 131:243201. [PMID: 38181131 DOI: 10.1103/physrevlett.131.243201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/30/2023] [Accepted: 10/26/2023] [Indexed: 01/07/2024]
Abstract
Photoinduced phase transitions in correlated materials promise diverse applications from ultrafast switches to optoelectronics. Resolving those transitions and possible metastable phases temporally are key enablers for these applications, but challenge existing experimental approaches. Extreme nonlinear optics can help probe phase changes, as higher-order nonlinearities have higher sensitivity and temporal resolution to band structure and lattice deformations. Here the ultrafast transition from the semiconducting to the metallic phases in polycrystalline thin-film NbO_{2} is investigated by time-resolved harmonic spectroscopy. The emission strength of all harmonic orders shows a steplike suppression when the excitation fluence exceeds a threshold (∼11-12 mJ/cm^{2}), below the fluence required for the thermal transition-a signature of the nonthermal emergence of a metallic phase within 100±20 fs. This observation is backed by full ab initio simulations as well as a 1D chain model of high-harmonic generation from both phases. Our results demonstrate femtosecond harmonic probing of phase transitions and nonthermal dynamics in solids.
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Affiliation(s)
- Z Nie
- Advanced Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
| | - L Guery
- Advanced Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
| | - E B Molinero
- Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (ICMM-CSIC), E-28049 Madrid, Spain
| | - P Juergens
- Advanced Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
- Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, D-12489 Berlin, Germany
| | - T J van den Hooven
- Advanced Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
| | - Y Wang
- School of Physics and Electronic Engineering, Taishan University 525 Dongyue Street, Tai'an, Shandong, China
| | - A Jimenez Galan
- Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, D-12489 Berlin, Germany
| | - P C M Planken
- Advanced Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - R E F Silva
- Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (ICMM-CSIC), E-28049 Madrid, Spain
- Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, D-12489 Berlin, Germany
| | - P M Kraus
- Advanced Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
- Department of Physics and Astronomy, and LaserLaB, Vrije Universiteit, De Boelelaan 1105,1081 HV Amsterdam, The Netherlands
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Wang Y, Iyikanat F, Bai X, Hu X, Das S, Dai Y, Zhang Y, Du L, Li S, Lipsanen H, García de Abajo FJ, Sun Z. Optical Control of High-Harmonic Generation at the Atomic Thickness. NANO LETTERS 2022; 22:8455-8462. [PMID: 36305718 PMCID: PMC9650768 DOI: 10.1021/acs.nanolett.2c02711] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 10/14/2022] [Indexed: 06/16/2023]
Abstract
High-harmonic generation (HHG), an extreme nonlinear optical phenomenon beyond the perturbation regime, is of great significance for various potential applications, such as high-energy ultrashort pulse generation with outstanding spatiotemporal coherence. However, efficient active control of HHG is still challenging due to the weak light-matter interaction displayed by currently known materials. Here, we demonstrate optically controlled HHG in monolayer semiconductors via the engineering of interband polarization. We find that HHG can be efficiently controlled in the excitonic spectral region with modulation depths up to 95% and ultrafast response speeds of several picoseconds. Quantitative time-domain theory of the nonlinear optical susceptibilities in monolayer semiconductors further corroborates these experimental observations. Our demonstration not only offers an in-depth understanding of HHG but also provides an effective approach toward active optical devices for strong-field physics and extreme nonlinear optics.
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Affiliation(s)
- Yadong Wang
- Department
of Electronics and Nanoengineering, Aalto
University, Espoo02150, Finland
| | - Fadil Iyikanat
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, 08860Castelldefels, Barcelona, Spain
| | - Xueyin Bai
- Department
of Electronics and Nanoengineering, Aalto
University, Espoo02150, Finland
| | - Xuerong Hu
- Department
of Electronics and Nanoengineering, Aalto
University, Espoo02150, Finland
- International
Cooperation Base of Photoelectric Technology and Functional Materials,
and Institute of Photonics and Photon-Technology, Northwest University, Xi’an710069, China
| | - Susobhan Das
- Department
of Electronics and Nanoengineering, Aalto
University, Espoo02150, Finland
| | - Yunyun Dai
- Department
of Electronics and Nanoengineering, Aalto
University, Espoo02150, Finland
| | - Yi Zhang
- Department
of Electronics and Nanoengineering, Aalto
University, Espoo02150, Finland
| | - Luojun Du
- Department
of Electronics and Nanoengineering, Aalto
University, Espoo02150, Finland
| | - Shisheng Li
- WPI
International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba305-0044, Japan
| | - Harri Lipsanen
- Department
of Electronics and Nanoengineering, Aalto
University, Espoo02150, Finland
| | - F. Javier García de Abajo
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, 08860Castelldefels, Barcelona, Spain
- ICREA-Institució
Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010Barcelona, Spain
| | - Zhipei Sun
- Department
of Electronics and Nanoengineering, Aalto
University, Espoo02150, Finland
- QTF Centre
of Excellence, Department of Applied Physics, Aalto University, Espoo02150, Finland
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8
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Agueny H. Tuning the electronic band structure of metal surfaces for enhancing high-order harmonic generation. J Chem Phys 2021; 154:244702. [PMID: 34241332 DOI: 10.1063/5.0049532] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
High-harmonic generation (HHG) from the condensed matter phase holds promise to promote future cutting-edge research in the emerging field of attosecond nanoscopy. The key for the progress of the field relies on the capability of the existing schemes to enhance the harmonic yield and to push the photon energy cutoff to the extreme-ultraviolet (XUV, 10-100 eV) regime and beyond toward the spectral "water window" region (282-533 eV). Here, we demonstrate a coherent control scheme of HHG, which we show to give rise to quantum modulations in the XUV region. These modulations are shown to be caused by quantum-path interferences and are found to exhibit a strong sensitivity to the delocalized character of bulk states of the material. The control scheme is based on exploring surface states in transition-metal surfaces and, specifically, tuning the electronic structure of the metal surface itself together with the use of optimal chirped pulses. Moreover, we show that the use of such pulses having moderate intensities permits us to push the harmonic cutoff further to the spectral water window region and that the extension is found to be robust against the change in the intrinsic properties of the material. The scenario is numerically implemented using a minimal model by solving the time-dependent Schrödinger equation for the metal surface Cu(111) initially prepared in the surface state. Our findings elucidate the importance of metal surfaces for generating coherent isolated attosecond XUV and soft-x-ray pulses and for designing compact solid-state HHG devices.
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Affiliation(s)
- Hicham Agueny
- Department of Physics and Technology, University of Bergen, Allegt. 55, N-5007 Bergen, Norway
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