98%
921
2 minutes
20
Generating Bessel-Gauss beams in the extreme ultraviolet (EUV) with attosecond pulse durations poses a significant challenge due to the limitations of conventional transmission optical components. Here, we propose a novel approach to produce such beams by inducing an annular EUV source through high-order harmonic generation (HHG) under nonadiabatic phase-matching conditions. The resulting light pulse maintains temporal coherence and manifests attosecond pulse trains as confirmed by the reconstruction of attosecond beating by interference of two-photon transitions (RABBIT) measurements. Macroscopic HHG calculations reproduce the measured spatiotemporal structures, demonstrating the plasma-induced spatial modulation on the formation of an annular source. Propagation simulations further confirm the feasibility of this approach for generating attosecond Bessel-Gauss beams, presenting exciting prospects for various applications in EUV photonics and attosecond science.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC12053678 | PMC |
http://dx.doi.org/10.1038/s41377-025-01845-7 | DOI Listing |
Phys Rev Lett
August 2025
Huazhong University of Science and Technology, Wuhan National Laboratory for Optoelectronics and School of Physics, Wuhan 430074, China.
We propose a scheme for retrieving the ultrafast valley polarization (VP) dynamics in two-dimensional hexagonal materials via attosecond circular dichroism (CD) transient absorption spectroscopy. This approach builds on the CD transition between the first and higher conduction bands induced by the circularly polarized probe pulses. The population imbalance at nonequivalent valleys in the first conduction band is proportionally mapped onto the difference in absorption coefficients of two probe pulses with opposite helicities, supporting an unprecedented quantitative retrieval of the corresponding VP dynamics with subfemtosecond time resolution.
View Article and Find Full Text PDFJ Phys Chem Lett
September 2025
Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, UiT The Arctic University of Norway, 9037 Tromsø, Norway.
Chiral systems exhibit unique properties traditionally linked to their asymmetric spatial arrangement. Recently, multiple laser pulses were shown to induce purely electronic chiral states without altering the nuclear configuration. Here, we propose and numerically demonstrate a simpler realization of light-induced electronic chirality that is long-lived and occurs well before the onset of nuclear motion and decoherence.
View Article and Find Full Text PDFNature
September 2025
Laboratorium für Physikalische Chemie, ETH Zürich, Zürich, Switzerland.
Many chirality-sensitive light-matter interactions are governed by chiral electron dynamics. Therefore, the development of advanced technologies making use of chiral phenomena would critically benefit from measuring and controlling chiral electron dynamics on their natural attosecond timescales. Such endeavours have so far been hampered by the lack of characterized circularly polarized attosecond pulses, an obstacle that has recently been overcome.
View Article and Find Full Text PDFJ Phys Chem Lett
August 2025
Nantes Université, CNRS, CEISAM UMR 6230, F-44000 Nantes, France.
Short-in-time, broad-in-energy attosecond or few-femtosecond pulses can excite coherent superpositions of several electronic states in molecules. This results in ultrafast charge oscillations known as charge migration. A key open question in the emerging field of attochemistry is whether these electron dynamics, which due to decoherence often last only for a few femtoseconds, can influence longer-time scale nuclear rearrangements.
View Article and Find Full Text PDFWe predict a novel, to our knowledge, phenomenon-the formation of arrays of localized dynamic microcavities during asymmetric collision of single-cycle optical pulses in a two-level medium. We demonstrate that such pulses, behaving similarly to 2 self-induced transparency solitons, generate dynamic structures whose shape is determined by the time delay between the pulses. The obtained results open new avenues for sub-wavelength light field control and can be applied in the development of ultrafast optical devices, topological photonics, and petahertz electronics.
View Article and Find Full Text PDF