Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism
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- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440,
- Department of Physics and JILA, University of Colorado, Boulder, CO 80309-0440,, Grupo de Investigación en Óptica Extrema, Universidad de Salamanca, Salamanca 37008, Spain,
- Solid State Institute and Physics Department, Technion, Haifa 32000, Israel,
- IT4Innovations Center, VSB Technical University of Ostrava, CZ 708 33 Ostrava, Czech Republic,, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Charles University in Prague, CZ-12116 Prague 2, Czech Republic,
- Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Charles University in Prague, CZ-12116 Prague 2, Czech Republic,, Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden,
- Department of Physics, University of California San Diego, La Jolla, CA 92093,
- Center for Magnetic Recording Research, University of California San Diego, La Jolla, CA 92093-0401,
- Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden,
- Faculty of Science, University of Sarajevo, 71000 Sarajevo, Bosnia and Herzegovina,, Academy of Sciences and Arts of Bosnia and Herzegovina, 71000 Sarajevo, Bosnia and Herzegovina,, Max-Born-Institut, 12489 Berlin, Germany
We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.
- Research Organization:
- Univ. of California, San Diego, CA (United States); Univ. of Colorado, Boulder, CO (United States)
- Sponsoring Organization:
- USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; National Science Foundation (NSF); REA; German Research Foundation (DFG); Swedish Research Council (SRC); Czech Science Foundation
- Grant/Contract Number:
- SC0001805; SC0003678; PHY-1125844; 328334; FIS2013-44174-P; PHY-1068706; GR 4234/1-1; 281043; 15-08740Y; SC0002002
- OSTI ID:
- 1235176
- Alternate ID(s):
- OSTI ID: 1348205; OSTI ID: 1682305
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 112 Journal Issue: 46; ISSN 0027-8424
- Publisher:
- Proceedings of the National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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