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Efficiency-optimized relativistic plasma harmonics for extreme fields

Abstract:

Bright harmonic radiation from relativistically oscillating laser plasmas offers a direct route for generating extreme electromagnetic fields. Theory predicts that under optimized conditions, the plasma medium can support strong spatiotemporal compression of laser energy in a coherent harmonic focus (CHF), delivering intensity boosts many orders of magnitude greater than the incident driving laser pulse1,2,3,4. Although diffraction-limited performance5 (spatial compression) and attosecond phase locking6,7,8 (temporal compression) have been demonstrated experimentally, efficient coupling of relativistically intense laser pulse energy into the emitted harmonic cone has not been realized so far. Here we demonstrate that this highly nonlinear interaction can be tailored to deliver the maximum conversion efficiencies predicted from simulations. By fine-tuning the temporal profile of the driving laser on sub-picosecond (<10−12 s) timescales, energies >9 mJ between the 12th and 47th harmonics are observed. These results are in agreement with the theoretically expected efficiency dependence on harmonic order, verifying that optimal conditions have been achieved in the generation process. This is the important final element required to achieve the expected intensity boosts from a CHF in experiments. Although obtaining spatiotemporal compression and optimal efficiency simultaneously remains challenging, the path to realizing extreme optical field strengths approaching the critical field of quantum electrodynamics (the Schwinger limit at >1016 V cm−1 or >1029 W cm−2) is now open, permitting all-optical studies of the quantum vacuum and new frontiers for intense attosecond science.

Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1038/s41586-026-10400-2

Authors

More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Atomic & Laser Physics
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Atomic & Laser Physics
Role:
Author


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Funder identifier:
https://ror.org/057g20z61
Grant:
ST/X005518/1
ST/V001655/1


Publisher:
Springer Nature
Journal:
Nature More from this journal
Volume:
652
Issue:
8112
Pages:
1153-1158
Publication date:
2026-04-22
Acceptance date:
2026-03-11
DOI:
EISSN:
1476-4687
ISSN:
0028-0836


Language:
English
Keywords:
Pubs id:
2404823
Local pid:
pubs:2404823
Deposit date:
2026-04-15
ARK identifier:

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