Probing the orbital angular momentum of intense vortex pulses with strong-field ionization

Abstract

With the rapid development of femtosecond lasers, the generation and application of optical vortices have been extended to the regime of intense-light-matter interaction. The characterization of the orbital angular momentum (OAM) of intense vortex pulses is very critical. Here, we propose and demonstrate a novel photoelectron-based scheme that can in situ distinguish the OAM of the focused intense femtosecond optical vortices without the modification of light helical phase. We employ two-color co-rotating intense circular fields in the strong-field photoionization experiment, in which one color light field is a plane wave serving as the probing pulses and the other one is the vortex pulses whose OAM needs to be characterized. We show that by controlling the spatial profile of the probing pulses, the OAM of the vortex pulses can be clearly identified by measuring the corresponding photoelectron momentum distributions or angle-resolved yields. This work provides a novel in situ detection scenario for the light pulse vorticity and has implications for the studies of ultrafast and intense complex light fields with optical OAM.

Generation and control of extreme ultraviolet free-space optical skyrmions with high harmonic generation

“…This work presents an important interface between strong-field physics and topology. 36,37 The generation and control of EUV skyrmions open a door to access skyrmionic dynamics in the broad ultraviolet region. Magnetic skyrmion Hall effect has been experimentally discovered recently; 38 however, to our knowledge, its optical analog has only been studied in theory.…”

Directly Determining Orbital Angular Momentum of Ultrashort Laguerre–Gauss Pulses via Spatially‐Resolved Autocorrelation Measurement

“…[27][28][29] For ultrashort pulses, transverse dispersion induced by the grating of complex-amplitude modulation would bring additional issues. Although a recent work has suggested that one can measure OAM of intense ultrashort pulses by exploiting strong-field ionization, [30] a simple technique towards commercial uses has not been developed.…”

“…More recently, the idea of the mode-projective measurement was used with nonlinear interactions and applied to numerous novel concepts, such as nonlinear modal detection and spatial mode teleportation, [31,32] enriching the already active topic of structured nonlinear optics. [30][31][32][33][34][35][36][37][38][39][40] The history of ultrashort-pulse characterization with nonlinear optics dates back to the birth of ultrafast lasers. Perhaps one of the most known techniques is the so-called autocorrelation technique based on second-harmonic generation (SHG) that is widely used to measure the temporal duration of ultrashort pulses.…”

Spatio-temporal sampling of near-petahertz vortex fields

“…It is thus not surprising that the use of attosecond streaking for the spatial reconstruction of near-petahertz vortex fields has not been reported yet. The measurement of vortex fields has mostly been limited to the measurement of the corresponding OAM carried by the light [29][30][31], not the field itself.…”