Strong-field photoelectron holography beyond the electric dipole approximation: A semiclassical analysis

Abstract

Strong-field photoelectron holography denotes the interference of various electron paths in laserinduced ionization of atoms, leading to interference patterns in the final momentum distribution, typically characterized by a strong signal of momenta pointing along the laser polarization axis and interference fringes roughly parallel to the polarization axis. For a quantitative trajectory-based description of holography beyond the electric dipole approximation and in the presence of the Coulomb potential, we develop a semiclassical model in which the initial conditions of outgoing electrons are set according to the beyond-dipole strong-field approximation for the tunnel ionization step. The phases associated with electron trajectories are evaluated following the prescription for semiclassical propagators. The validity of the method is confirmed by comparison to the numerical solution of the time-dependent Schrödinger equation in two spatial dimensions. The semiclassical model reproduces correctly the backward and forward shifts of the photoelectron momenta along the laser propagation axis that arise from beyond-dipole dynamics. The position of the central holographic interference fringe can be estimated already from a simplified Coulomb-free interference model that provides closed-form expressions for the beyond-dipole shifts. In three dimensions, Coulomb focusing causes a breakdown of the semiclassical model for final momenta with directions close to the polarization axis. We implement a beyond-dipole regularization procedure based on the concept of glory scattering, which was recently used to describe Coulomb focusing in the dipole approximation. While the position of the central maximum and higher-order fringes in three dimensions can already be obtained approximately by simpler semiclassical modeling, this glory model is able to predict the shape of the distribution in the close vicinity of the central maximum. Our results show that the violation of the dipole approximation in holography should be observable with mid-infrared fields, for which the forward/backward shifts can be comparable with the fringe spacing.

Subfemtosecond glory hologrammetry for vectorial optical waveform reconstruction

“…. This result has successfully interpreted the near-forward SFPH interference fringes in PMD [38,40,44].…”

Semiclassical Trajectory Perspective of Glory Rescattering in Strong-field Photoelectron Holography

“…The latter process is termed as rescattering or recollision. SFPH is tightly related to the quantum interference in the rescattering process [22][23][24][25][26]. Numerically, PMDs can be obtained by directly integrating the time-dependent Schrödinger equation (TDSE) [3,8,27,28] in full dimensionality (3D).…”

Magnetic-field effect in high-order above-threshold ionization

“…Additionally, photoelectron holography [13,14], i.e., the interference between direct and forward scattered electrons, dominates the distributions at intermediate energies below the classical cutoff of 2U p , where U p = E 2 0 /(4ω 2 ) is the ponderomotive potential of the driving laser field with electric field amplitude E 0 and frequency ω. In this region, the electron momentum p x,e is approximately given by p x,e ≈ E e /c [8,15,16]. Classically, energies higher than 2U p can only be reached by rescattering electrons [17,18], i.e., electrons that are elastically scattered into large angles followed by further acceleration in the laser field.…”