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Galán MF, Serrano J, Jarque EC, Borrego-Varillas R, Lucchini M, Reduzzi M, Nisoli M, Brahms C, Travers JC, Hernández-García C, San Roman J. Robust Isolated Attosecond Pulse Generation with Self-Compressed Subcycle Drivers from Hollow Capillary Fibers. ACS PHOTONICS 2024; 11:1673-1683. [PMID: 38645995 PMCID: PMC11027177 DOI: 10.1021/acsphotonics.3c01897] [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: 12/22/2023] [Revised: 03/05/2024] [Accepted: 03/05/2024] [Indexed: 04/23/2024]
Abstract
High-order harmonic generation (HHG) arising from the nonperturbative interaction of intense light fields with matter constitutes a well-established tabletop source of coherent extreme-ultraviolet and soft X-ray radiation, which is typically emitted as attosecond pulse trains. However, ultrafast applications increasingly demand isolated attosecond pulses (IAPs), which offer great promise for advancing precision control of electron dynamics. Yet, the direct generation of IAPs typically requires the synthesis of near-single-cycle intense driving fields, which is technologically challenging. In this work, we theoretically demonstrate a novel scheme for the straightforward and compact generation of IAPs from multicycle infrared drivers using hollow capillary fibers (HCFs). Starting from a standard, intense multicycle infrared pulse, a light transient is generated by extreme soliton self-compression in a HCF with decreasing pressure and is subsequently used to drive HHG in a gas target. Owing to the subcycle confinement of the HHG process, high-contrast IAPs are continuously emitted almost independently of the carrier-envelope phase (CEP) of the optimally self-compressed drivers. This results in a CEP-robust scheme which is also stable under macroscopic propagation of the high harmonics in a gas target. Our results open the way to a new generation of integrated all-fiber IAP sources, overcoming the efficiency limitations of usual gating techniques for multicycle drivers.
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Affiliation(s)
- Marina Fernández Galán
- Grupo
de Investigación en Aplicaciones del Láser y Fotónica,
Departamento de Física Aplicada, Universidad de Salamanca, Salamanca, 37008, Spain
- Unidad
de Excelencia en Luz y Materia Estructuradas (LUMES), Universidad de Salamanca, Salamanca, 37008, Spain
| | - Javier Serrano
- Grupo
de Investigación en Aplicaciones del Láser y Fotónica,
Departamento de Física Aplicada, Universidad de Salamanca, Salamanca, 37008, Spain
- Unidad
de Excelencia en Luz y Materia Estructuradas (LUMES), Universidad de Salamanca, Salamanca, 37008, Spain
| | - Enrique Conejero Jarque
- Grupo
de Investigación en Aplicaciones del Láser y Fotónica,
Departamento de Física Aplicada, Universidad de Salamanca, Salamanca, 37008, Spain
- Unidad
de Excelencia en Luz y Materia Estructuradas (LUMES), Universidad de Salamanca, Salamanca, 37008, Spain
| | - Rocío Borrego-Varillas
- Institute
for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche (CNR), Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Matteo Lucchini
- Institute
for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche (CNR), Piazza Leonardo da Vinci 32, Milano, 20133, Italy
- Department
of Physics, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Maurizio Reduzzi
- Institute
for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche (CNR), Piazza Leonardo da Vinci 32, Milano, 20133, Italy
- Department
of Physics, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Mauro Nisoli
- Institute
for Photonics and Nanotechnologies (IFN), Consiglio Nazionale delle Ricerche (CNR), Piazza Leonardo da Vinci 32, Milano, 20133, Italy
- Department
of Physics, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano, 20133, Italy
| | - Christian Brahms
- School
of Engineering and Physical Sciences, Heriot-Watt
University, Edinburgh, EH14 4AS, United
Kingdom
| | - John C. Travers
- School
of Engineering and Physical Sciences, Heriot-Watt
University, Edinburgh, EH14 4AS, United
Kingdom
| | - Carlos Hernández-García
- Grupo
de Investigación en Aplicaciones del Láser y Fotónica,
Departamento de Física Aplicada, Universidad de Salamanca, Salamanca, 37008, Spain
- Unidad
de Excelencia en Luz y Materia Estructuradas (LUMES), Universidad de Salamanca, Salamanca, 37008, Spain
| | - Julio San Roman
- Grupo
de Investigación en Aplicaciones del Láser y Fotónica,
Departamento de Física Aplicada, Universidad de Salamanca, Salamanca, 37008, Spain
- Unidad
de Excelencia en Luz y Materia Estructuradas (LUMES), Universidad de Salamanca, Salamanca, 37008, Spain
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2
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Schoenlein R, Elsaesser T, Holldack K, Huang Z, Kapteyn H, Murnane M, Woerner M. Recent advances in ultrafast X-ray sources. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2019; 377:20180384. [PMID: 30929633 DOI: 10.1098/rsta.2018.0384] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Over more than a century, X-rays have transformed our understanding of the fundamental structure of matter and have been an indispensable tool for chemistry, physics, biology, materials science and related fields. Recent advances in ultrafast X-ray sources operating in the femtosecond to attosecond regimes have opened an important new frontier in X-ray science. These advances now enable: (i) sensitive probing of structural dynamics in matter on the fundamental timescales of atomic motion, (ii) element-specific probing of electronic structure and charge dynamics on fundamental timescales of electronic motion, and (iii) powerful new approaches for unravelling the coupling between electronic and atomic structural dynamics that underpin the properties and function of matter. Most notable is the recent realization of X-ray free-electron lasers (XFELs) with numerous new XFEL facilities in operation or under development worldwide. Advances in XFELs are complemented by advances in synchrotron-based and table-top laser-plasma X-ray sources now operating in the femtosecond regime, and laser-based high-order harmonic XUV sources operating in the attosecond regime. This article is part of the theme issue 'Measurement of ultrafast electronic and structural dynamics with X-rays'.
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Affiliation(s)
- Robert Schoenlein
- 1 SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, CA 94025 , USA
| | - Thomas Elsaesser
- 2 Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie , 12489 Berlin , Germany
| | - Karsten Holldack
- 3 Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Albert-Einstein-Strasse 15, 12489 Berlin , Germany
| | - Zhirong Huang
- 1 SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park, CA 94025 , USA
| | - Henry Kapteyn
- 4 Department of Physics and JILA, University of Colorado , Boulder, CO 80309-0440 , USA
| | - Margaret Murnane
- 4 Department of Physics and JILA, University of Colorado , Boulder, CO 80309-0440 , USA
| | - Michael Woerner
- 2 Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie , 12489 Berlin , Germany
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3
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Hareli L, Lobachinsky L, Shoulga G, Eliezer Y, Michaeli L, Bahabad A. On-the-Fly Control of High-Harmonic Generation Using a Structured Pump Beam. PHYSICAL REVIEW LETTERS 2018; 120:183902. [PMID: 29775338 DOI: 10.1103/physrevlett.120.183902] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Indexed: 06/08/2023]
Abstract
We demonstrate experimentally a relatively simple yet powerful all-optical enhancement and control technique for high harmonic generation. This is achieved by using as a pump beam two different spatial optical modes interfering together to realize tunable periodic quasi-phase matching of the interaction. With this technique, we demonstrate on-the-fly quasi-phase matching of harmonic orders 29-41 at ambient gas pressure levels of 50 and 100 Torr, where an up to 100-fold enhancement of the emission is observed. The technique is scalable to different harmonic orders and ambient pressure conditions.
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Affiliation(s)
- Liran Hareli
- Department of Physical Electronics, School of Electrical Engineering, Fleischman Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Lilya Lobachinsky
- Department of Physical Electronics, School of Electrical Engineering, Fleischman Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Georgiy Shoulga
- Department of Physical Electronics, School of Electrical Engineering, Fleischman Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Yaniv Eliezer
- Department of Physical Electronics, School of Electrical Engineering, Fleischman Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Linor Michaeli
- Department of Physical Electronics, School of Electrical Engineering, Fleischman Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Alon Bahabad
- Department of Physical Electronics, School of Electrical Engineering, Fleischman Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel
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4
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Hernández-García C, Popmintchev T, Murnane MM, Kapteyn HC, Plaja L, Becker A, Jaron-Becker A. Isolated broadband attosecond pulse generation with near- and mid-infrared driver pulses via time-gated phase matching. OPTICS EXPRESS 2017; 25:11855-11866. [PMID: 28788745 DOI: 10.1364/oe.25.011855] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present a theoretical analysis of the time-gated phase matching (ionization gating) mechanism in high-order harmonic generation for the isolation of attosecond pulses at near-infrared and mid-infrared driver wavelengths, for both few-cycle and multi-cycle driving laser pulses. Results of our high harmonic generation and three-dimensional propagation simulations show that broadband isolated pulses spanning from the extreme-ultraviolet well into the soft X-ray region of the spectrum can be generated for both few-cycle and multi-cycle laser pulses. We demonstrate the key role of absorption and group velocity matching for generating bright, isolated, attosecond pulses using long wavelength multi-cycle pulses. Finally, we show that this technique is robust against carrier-envelope phase and peak intensity variations.
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5
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Nisoli M, Decleva P, Calegari F, Palacios A, Martín F. Attosecond Electron Dynamics in Molecules. Chem Rev 2017; 117:10760-10825. [DOI: 10.1021/acs.chemrev.6b00453] [Citation(s) in RCA: 261] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Mauro Nisoli
- Department
of Physics, Politecnico di Milano, 20133 Milano, Italy
- Institute for Photonics and Nanotechnologies, IFN-CNR, 20133 Milano, Italy
| | - Piero Decleva
- Dipartimento
di Scienze Chimiche e Farmaceutiche, Universitá di Trieste and IOM- CNR, 34127 Trieste, Italy
| | - Francesca Calegari
- Institute for Photonics and Nanotechnologies, IFN-CNR, 20133 Milano, Italy
- Center for Free-Electron Laser Science, DESY, 22607 Hamburg, Germany
- Department
of Physics, University of Hamburg, 20355 Hamburg, Germany
| | - Alicia Palacios
- Departamento
de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Fernando Martín
- Departamento
de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia, 28049 Madrid, Spain
- Condensed
Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
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6
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Tao Y, Goh SJ, Bastiaens HMJ, van der Slot PJM, Biedron SG, Milton SV, Boller KJ. Temporal model for quasi-phase matching in high-order harmonic generation. OPTICS EXPRESS 2017; 25:3621-3638. [PMID: 28241575 DOI: 10.1364/oe.25.003621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present a model for quasi-phase matching (QPM) in high-order harmonic generation (HHG). Using a one-dimensional description, we analyze the time-dependent, ultrafast wave-vector balance to calculate the on-axis harmonic output versus time, from which we obtain the output pulse energy. Considering, as an example, periodically patterned argon gas, as may be provided with a grid in a cluster jet, we calculate the harmonic output during different time intervals within the drive laser pulse duration. We find that identifying a suitable single spatial period is not straightforward due to the complex and ultrafast plasma dynamics that underlies HHG at increased intensities. The maximum on-axis harmonic pulse energy is obtained when choosing the QPM period to phase match HHG at the leading edge of the drive laser pulse.
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7
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Jin C, Hong KH, Lin CD. Optimal generation of spatially coherent soft X-ray isolated attosecond pulses in a gas-filled waveguide using two-color synthesized laser pulses. Sci Rep 2016; 6:38165. [PMID: 27929036 PMCID: PMC5144061 DOI: 10.1038/srep38165] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 11/04/2016] [Indexed: 11/08/2022] Open
Abstract
We numerically demonstrate the generation of intense, low-divergence soft X-ray isolated attosecond pulses in a gas-filled hollow waveguide using synthesized few-cycle two-color laser waveforms. The waveform is a superposition of a fundamental and its second harmonic optimized such that highest harmonic yields are emitted from each atom. We then optimize the gas pressure and the length and radius of the waveguide such that bright coherent high-order harmonics with angular divergence smaller than 1 mrad are generated, for photon energy from the extreme ultraviolet to soft X-rays. By selecting a proper spectral range enhanced isolated attosecond pulses are generated. We study how dynamic phase matching caused by the interplay among waveguide mode, neutral atomic dispersion, and plasma effect is achieved at the optimal macroscopic conditions, by performing time-frequency analysis and by analyzing the evolution of the driving laser's electric field during the propagation. Our results, when combined with the on-going push of high-repetition-rate lasers (sub- to few MHz's) may eventually lead to the generation of high-flux, low-divergence soft X-ray tabletop isolated attosecond pulses for applications.
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Affiliation(s)
- Cheng Jin
- Department of Applied Physics, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, P. R. China
| | - Kyung-Han Hong
- Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139, USA
| | - C. D. Lin
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
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8
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Hernández-García C, Holgado W, Plaja L, Alonso B, Silva F, Miranda M, Crespo H, Sola IJ. Carrier-envelope-phase insensitivity in high-order harmonic generation driven by few-cycle laser pulses. OPTICS EXPRESS 2015; 23:21497-21508. [PMID: 26367996 DOI: 10.1364/oe.23.021497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present evidence for self-stabilization of the relative spectral phase of high-order harmonic emission against intensity variations of the driving field. Our results demonstrate that, near the laser focus, phase matching of the harmonic field from a macroscopic target can compensate for the intensity dependence of the intrinsic phase of the harmonics emitted by a single radiator. As a consequence, we show experimentally and theoretically the insensitivity of the harmonic spectra produced at the laser focus against variations of the carrier-envelope phase (CEP) of a sub-two-cycle driving field. In addition, the associated attosecond pulse trains exhibit phase locking against CEP changes of the few-cycle driver.
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9
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Generation of bright isolated attosecond soft X-ray pulses driven by multicycle midinfrared lasers. Proc Natl Acad Sci U S A 2014; 111:E2361-7. [PMID: 24850866 DOI: 10.1073/pnas.1407421111] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
High harmonic generation driven by femtosecond lasers makes it possible to capture the fastest dynamics in molecules and materials. However, to date the shortest subfemtosecond (attosecond, 10(-18) s) pulses have been produced only in the extreme UV region of the spectrum below 100 eV, which limits the range of materials and molecular systems that can be explored. Here we experimentally demonstrate a remarkable convergence of physics: when midinfrared lasers are used to drive high harmonic generation, the conditions for optimal bright, soft X-ray generation naturally coincide with the generation of isolated attosecond pulses. The temporal window over which phase matching occurs shrinks rapidly with increasing driving laser wavelength, to the extent that bright isolated attosecond pulses are the norm for 2-µm driving lasers. Harnessing this realization, we experimentally demonstrate the generation of isolated soft X-ray attosecond pulses at photon energies up to 180 eV for the first time, to our knowledge, with a transform limit of 35 attoseconds (as), and a predicted linear chirp of 300 as. Most surprisingly, advanced theory shows that in contrast with as pulse generation in the extreme UV, long-duration, 10-cycle, driving laser pulses are required to generate isolated soft X-ray bursts efficiently, to mitigate group velocity walk-off between the laser and the X-ray fields that otherwise limit the conversion efficiency. Our work demonstrates a clear and straightforward approach for robustly generating bright isolated attosecond pulses of electromagnetic radiation throughout the soft X-ray region of the spectrum.
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10
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Zhu X, Zhang C, Gu M, Yao J. Quantum path selection in high-order harmonic generation from aligned molecules. OPTICS EXPRESS 2014; 22:7947-7952. [PMID: 24718170 DOI: 10.1364/oe.22.007947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We theoretically investigate high-order harmonic generation (HHG) from aligned N(2) molecules with a driving field composed of two-color circularly polarized laser pulses. It is shown that the combination of N(2) molecules and the waveform-controlled laser field allows us to select either long or short quantum path, depending on molecular alignment angles, while in atom Ar, two paths show comparable contribution to HHG. The selection of single quantum path in aligned N(2) molecules leads to an ultrabroad and smooth XUV supercontinuum, giving rise to isolated attosecond pulses generation. Moreover, we can control the intensity ratio of two attosecond pulses by adjusting the molecular alignment angles, providing an opportunity for attosecond pump-probe technique.
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11
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Mashiko H, Bell MJ, Beck AR, Neumark DM, Leone SR. Frequency Tunable Attosecond Apparatus. ACTA ACUST UNITED AC 2014. [DOI: 10.1007/978-3-319-00521-8_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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12
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Hernández-García C, Pérez-Hernández JA, Popmintchev T, Murnane MM, Kapteyn HC, Jaron-Becker A, Becker A, Plaja L. Zeptosecond high harmonic keV x-ray waveforms driven by midinfrared laser pulses. PHYSICAL REVIEW LETTERS 2013; 111:033002. [PMID: 23909315 DOI: 10.1103/physrevlett.111.033002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Indexed: 05/24/2023]
Abstract
We demonstrate theoretically that the temporal structure of high harmonic x-ray pulses generated with midinfrared lasers differs substantially from those generated with near-infrared pulses, especially at high photon energies. In particular, we show that, although the total width of the x-ray bursts spans femtosecond time scales, the pulse exhibits a zeptosecond structure due to the interference of high harmonic emission from multiple reencounters of the electron wave packet with the ion. Properly filtered and without any compensation of the chirp, regular subattosecond keV waveforms can be produced.
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Affiliation(s)
- C Hernández-García
- Grupo de Investigación en Óptica Extrema, Universidad de Salamanca, E-37008 Salamanca, Spain.
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13
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Popmintchev T, Chen MC, Popmintchev D, Arpin P, Brown S, Alisauskas S, Andriukaitis G, Balciunas T, Mucke OD, Pugzlys A, Baltuska A, Shim B, Schrauth SE, Gaeta A, Hernandez-Garcia C, Plaja L, Becker A, Jaron-Becker A, Murnane MM, Kapteyn HC. Bright Coherent Ultrahigh Harmonics in the keV X-ray Regime from Mid-Infrared Femtosecond Lasers. Science 2012; 336:1287-91. [DOI: 10.1126/science.1218497] [Citation(s) in RCA: 1273] [Impact Index Per Article: 106.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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14
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Affiliation(s)
- Lukas Gallmann
- Physics Department, Eidgenössische Technische Hochschule Zürich, CH-8093 Zurich, Switzerland;
| | - Claudio Cirelli
- Physics Department, Eidgenössische Technische Hochschule Zürich, CH-8093 Zurich, Switzerland;
| | - Ursula Keller
- Physics Department, Eidgenössische Technische Hochschule Zürich, CH-8093 Zurich, Switzerland;
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15
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Chen MC, Arpin P, Popmintchev T, Gerrity M, Zhang B, Seaberg M, Popmintchev D, Murnane MM, Kapteyn HC. Bright, coherent, ultrafast soft X-ray harmonics spanning the water window from a tabletop light source. PHYSICAL REVIEW LETTERS 2010; 105:173901. [PMID: 21231046 DOI: 10.1103/physrevlett.105.173901] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2010] [Indexed: 05/30/2023]
Abstract
We demonstrate fully phase-matched high harmonic emission spanning the water window spectral region important for nano- and bioimaging and a breadth of materials and molecular dynamics studies. We also generate the broadest bright coherent bandwidth (≈300 eV) to date from any light source, small or large, that is consistent with a single subfemtosecond burst. The harmonic photon flux at 0.5 keV is 10³ higher than demonstrated previously. This work extends bright, spatially coherent, attosecond pulses into the soft x-ray region for the first time.
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Affiliation(s)
- M-C Chen
- JILA, University of Colorado at Boulder, 80309-0440, USA
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16
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La-O-Vorakiat C, Siemens M, Murnane MM, Kapteyn HC, Mathias S, Aeschlimann M, Grychtol P, Adam R, Schneider CM, Shaw JM, Nembach H, Silva TJ. Ultrafast demagnetization dynamics at the M edges of magnetic elements observed using a tabletop high-harmonic soft x-ray source. PHYSICAL REVIEW LETTERS 2009; 103:257402. [PMID: 20366281 DOI: 10.1103/physrevlett.103.257402] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Indexed: 05/23/2023]
Abstract
We use few-femtosecond soft x-ray pulses from high-harmonic generation to extract element-specific demagnetization dynamics and hysteresis loops of a compound material for the first time. Using a geometry where high-harmonic beams are reflected from a magnetized Permalloy grating, large changes in the reflected intensity of up to 6% at the M absorption edges of Fe and Ni are observed when the magnetization is reversed. A short pump pulse is used to destroy the magnetic alignment, which allows us to measure the fastest, elementally specific demagnetization dynamics, with 55 fs time resolution. The use of high harmonics for probing magnetic materials promises to combine nanometer spatial resolution, elemental specificity, and femtosecond-to-attosecond time resolution, making it possible to address important fundamental questions in magnetism.
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Affiliation(s)
- Chan La-O-Vorakiat
- Department of Physics and JILA, University of Colorado, Boulder, Colorado 80309-0440, USA.
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18
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Gagnon J, Yakovlev VS. The robustness of attosecond streaking measurements. OPTICS EXPRESS 2009; 17:17678-17693. [PMID: 19907553 DOI: 10.1364/oe.17.017678] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We investigate attosecond streaking measurements, where a spectrogram is described by an ensemble of electron wave packets. Such a description may be required for processes more complex than direct photoemission from an isolated atom; an ensemble of wave packets may also be needed to describe the role of shot-to-shot fluctuations or a non-uniform spatio-temporal profile of attosecond light pulses. Under these conditions, we examine the performance of conventional (FROG) analysis of attosecond streaking measurements.
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Affiliation(s)
- Justin Gagnon
- Max Planck Institut Für Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching, Germany.
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19
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Phase matching of high harmonic generation in the soft and hard X-ray regions of the spectrum. Proc Natl Acad Sci U S A 2009; 106:10516-21. [PMID: 19541611 DOI: 10.1073/pnas.0903748106] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We show how bright, tabletop, fully coherent hard X-ray beams can be generated through nonlinear upconversion of femtosecond laser light. By driving the high-order harmonic generation process using longer-wavelength midinfrared light, we show that, in theory, fully phase-matched frequency upconversion can extend into the hard X-ray region of the spectrum. We verify our scaling predictions experimentally by demonstrating phase matching in the soft X-ray region of the spectrum around 330 eV, using ultrafast driving laser pulses at 1.3-microm wavelength, in an extended, high-pressure, weakly ionized gas medium. We also show through calculations that scaling of the overall conversion efficiency is surprisingly favorable as the wavelength of the driving laser is increased, making tabletop, fully coherent, multi-keV X-ray sources feasible. The rapidly decreasing microscopic single-atom yield, predicted for harmonics driven by longer-wavelength lasers, is compensated macroscopically by an increased optimal pressure for phase matching and a rapidly decreasing reabsorption of the generated X-rays.
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