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Directional asymmetry in strong-field ionization induced by a terahertz-assisted laser pulse

F. Žgalj1, A. S. Jašarević1, D. Habibović1,*, and D. B. Milošević1,2

  • *Contact author: dhfizika1@gmail.com
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Phys. Rev. Research 8, 023211 – Published 27 May, 2026

DOI: https://doi.org/10.1103/w4v4-6m6v

Abstract

We investigate directional asymmetry in strong-field ionization driven by a few-cycle near-infrared laser pulse assisted by a time-delayed terahertz (THz) pulse. Within the strong-field approximation, we show that the relative delay between the laser and THz pulses provides an efficient control parameter for steering photoelectron emission along the laser polarization axis. Energy-resolved photoelectron spectra, momentum distributions, and asymmetry parameter demonstrate a pronounced and tunable left-right asymmetry for both direct and rescattered electrons, governed by the value of the THz vector potential during the ionization window. This control is significantly stronger than that achievable by varying the carrier-envelope phase of the laser pulse alone and remains robust with respect to variations of the THz-pulse parameters and focal averaging. Our results build upon the theoretical concept introduced earlier [Milošević, Opt. Lett. 47, 1669 (2022)], whose predictions were subsequently confirmed by the experiment [Mitrofanov et al., Opt. Lett. 50, 6626 (2025)], establishing THz-assisted strong-field ionization as a reliable and experimentally validated approach for controlling photoelectron emission on ultrafast timescales.

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Phys. Rev. Research 8, 023211– Published 27 May, 2026
  • Received 18 January 2026
  • Accepted 11 May 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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