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Attosecond vortex pulse trains
DOI:10.1364/OPTICA.517702.png)
Abstract
En 中文
The landscape of ultrafast structured light pulses has significantly advanced thanks to the ability of high-order harmonicgeneration (HHG) to translate the spatial properties of infrared laser beams to the extreme-ultraviolet (EUV) spectralrange. In particular, the up-conversion of orbital angular momentum (OAM) has enabled the generation of high-orderharmonics whose OAM scales linearly with the harmonic order and the topological charge of the driving field. Havinga well-defined OAM, each harmonic is emitted as an EUV femtosecond vortex pulse. However, the order-dependentOAM across the harmonic comb precludes the synthesis of attosecond vortex pulses. Here we demonstrate a methodfor generating attosecond vortex pulse trains, i.e., a succession of attosecond pulses with a helical wavefront, resultingfrom the coherent superposition of a comb of EUV high-order harmonics with thesameOAM. By driving HHG with apolarization tilt-angle fork grating, two spatially separated circularly polarized high-order harmonic beams with order-independent OAM are created. Our work opens the route towards attosecond-resolved light-matter interactions withtwo extra degrees of freedom, spin and OAM, which are particularly interesting for probing chiral systems and magneticmaterials.
Keywords:
ORBITAL ANGULAR-MOMENTUM
HIGH-HARMONIC GENERATION
POLARIZATION
LIGHT
IONIZATION
PHYSICS
DRIVEN
PHASE
BEAMS
Journal
IF:
8.5
Papers:
2.4K
Citations:
2.1W

