Ultrafast coherent x-rays from tabletop lasers—a new tool
for science and technology
Henry C. Kapteyn and Margaret M. Murnane
Department of Physics, JILA, and NSF ERC in EUV Science and Technology, University of Colorado and NIST, Boulder, CO 80309-0440
E-mail: Henry.Kapteyn@Colorado.edu
The discovery of x-rays made possible not-only new medical technologies, but also allowed man to “see” at the
atomic scale for the first time, revolutionizing our understanding of matter. Efforts to bring x-ray techniques to
femtosecond time-scales—the fundamental atomic time scale— have been ongoing for the past ~¼ century, and are
now providing new insight into the behavior of matter. Key to this work has been to understand the coherent highorder harmonic generation (HHG) upconversion process. HHG allows for the light from a high-power femtosecond
laser to be coherently upconverted from the infrared into the soft x-ray region of the spectrum, with each x-ray
photon resulting from the coherent combination of hundreds or even thousands of photons from the driving laser.
The resulting femtosecond and attosecond HHG x-ray sources allow us to probe, using a tabletop setup, the fastest
charge, spin and energy transport processes. The capabilities of these sources have increased dramatically with our
recent demonstration of bright sources with photon energy >1 keV.[1-3] Recent applications include probing the
dynamics of the quantum exchange interaction fundamental to magnetic materials;[4-8] the use of coherent HHG
light for tabletop nano-imaging with record 22 nm resolution;[9-11] and studies of the physical limits of energy flow
at the nanoscale.[12,13]
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T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys,
A. Baltuška, B. Shim, S. E. Schrauth, A. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C.
Kapteyn, "Bright Coherent Ultrahigh Harmonics in the keV X-ray Regime from Mid-Infrared Femtosecond Lasers," Science 336(6086),
1287-1291 (2012).
T. Popmintchev, M. C. Chen, P. Arpin, M. M. Murnane, and H. C. Kapteyn, "The attosecond nonlinear optics of bright coherent X-ray
generation," Nature Photonics 4(12), 822-832 (2010).
M. C. Chen, P. Arpin, T. Popmintchev, M. Gerrity, B. Zhang, M. Seaberg, D. Popmintchev, M. M. Murnane, and H. C. Kapteyn, "Bright,
Coherent, Ultrafast Soft X-Ray Harmonics Spanning the Water Window from a Tabletop Light Source," Physical Review Letters 105(17),
173901 (2010).
E. Turgut, C. La-o-vorakiat, J. M. Shaw, P. Grychtol, H. T. Nembach, D. Rudolf, R. Adam, M. Aeschlimann, C. M. Schneider, T. J. Silva,
M. M. Murnane, H. C. Kapteyn, and S. Mathias, "Controlling the Competition between Optically Induced Ultrafast Spin-Flip Scattering and
Spin Transport in Magnetic Multilayers," Physical Review Letters 110(19), 197201 (2013).
D. Rudolf, C. La-O-Vorakiat, M. Battiato, R. Adam, J. M. Shaw, E. Turgut, P. Maldonado, S. Mathias, P. Grychtol, H. T. Nembach, T. J.
Silva, M. Aeschlimann, H. C. Kapteyn, M. M. Murnane, C. M. Schneider, and P. M. Oppeneer, "Ultrafast magnetization enhancement in
metallic multilayers driven by superdiffusive spin current," Nature Communications 3, 1037 (2012).
C. La-O-Vorakiat, E. Turgut, C. A. Teale, H. C. Kapteyn, M. M. Murnane, S. Mathias, M. Aeschlimann, C. M. Schneider, J. M. Shaw, H.
T. Nembach, and T. J. Silva, "Ultrafast Demagnetization Measurements Using Extreme Ultraviolet Light: Comparison of Electronic and
Magnetic Contributions," Physical Review X 2(1), 011005 (2012).
C. La-O-Vorakiat, M. Siemens, M. M. Murnane, H. C. Kapteyn, S. Mathias, M. Aeschlimann, P. Grychtol, R. Adam, C. M. Schneider, J.
M. Shaw, H. Nembach, and T. J. Silva, "Ultrafast Demagnetization Dynamics at the M Edges of Magnetic Elements Observed Using a
Tabletop High-Harmonic Soft X-Ray Source," Physical Review Letters 103(25), 257402/257401-257404 (2009).
S. Mathias, C. La-O-Vorakiat, P. Grychtol, P. Granitzka, E. Turgut, J. Shaw, R. Adam, H. Nembach, M. Siemens, S. Eich, C. M. Schneider,
T. J. Silva, M. Aeschlimann, M. M. Murnane, and H. C. Kapteyn, "Probing the timescale of the exchange interaction in a ferromagnetic
alloy," PNAS 109, 4792 (2012).
B. Zhang, M. D. Seaberg, D. E. Adams, D. F. Gardner, E. R. Shanblatt, J. M. Shaw, W. Chao, E. M. Gullikson, F. Salmassi, H. C. Kapteyn,
and M. M. Murnane, "Full field tabletop EUV coherent diffractive imaging in a transmission geometry," Optics Express 21(19), 2197021980 (2013).
M. D. Seaberg, D. E. Adams, E. L. Townsend, D. A. Raymondson, W. F. Schlotter, Y. W. Liu, C. S. Menoni, L. Rong, C. C. Chen, J. W.
Miao, H. C. Kapteyn, and M. M. Murnane, "Ultrahigh 22 nm resolution coherent diffractive imaging using a desktop 13 nm high harmonic
source," Optics Express 19(23), 22470-22479 (2011).
R. L. Sandberg, C. Y. Song, P. W. Wachulak, D. A. Raymondson, A. Paul, B. Amirbekian, E. Lee, A. E. Sakdinawat, C. La-O-Vorakiat, M.
C. Marconi, C. S. Menoni, M. M. Murnane, J. J. Rocca, H. C. Kapteyn, and J. W. Miao, "High numerical aperture tabletop soft x-ray
diffraction microscopy with 70-nm resolution," Proceedings of the National Academy of Sciences of the United States of America 105(1),
24-27 (2008).
D. Nardi, M. Travagliati, M. E. Siemens, Q. Li, M. M. Murnane, H. C. Kapteyn, G. Ferrini, F. Parmigiani, and F. Banfi, "Probing
Thermomechanics at the Nanoscale: Impulsively Excited Pseudosurface Acoustic Waves in Hypersonic Phononic Crystals," Nano Letters
11(10), 4126-4133 (2011).
M. E. Siemens, Q. Li, R. G. Yang, K. A. Nelson, E. H. Anderson, M. M. Murnane, and H. C. Kapteyn, "Quasi-ballistic thermal transport
from nanoscale interfaces observed using ultrafast coherent soft X-ray beams," Nature Materials 9(1), 26-30 (2010).