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  • Open Access

Tunable harmonic frequency combs via dual-beam or structured-target laser-solid interactions

Raoul Trines1,*, Holger Schmitz1, Martin King2,3, Paul McKenna2,3, and Robert Bingham1,2

  • *Contact author: raoul.trines@stfc.ac.uk
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Phys. Rev. Research 8, 013241 – Published 5 March, 2026

DOI: https://doi.org/10.1103/j531-q3tk

Abstract

When an intense laser pulse strikes a flat solid target at normal incidence, only odd, equally spaced harmonics are typically generated. Using particle-in-cell simulations, we show that introducing transverse spatial modulation—either via two beams incident at small opposing angles or via a single beam reflecting from a corrugated surface—produces a two-dimensional harmonic spectrum. Selecting the emission through a narrow slit isolates an angle-dependent subset of harmonics, forming a tunable frequency comb controlled by both the viewing angle and the drive-laser frequency. Distinct combs arise for s- and p-polarized emission, while increasing the focal spot size reduces divergence and improves efficiency. Additional control is achieved by varying beam frequencies, target tilt, or beam number. Replacing the dual-beam configuration with a single beam and structured surface provides equivalent functionality with significantly reduced experimental complexity.

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Phys. Rev. Research 8, 013241– Published 5 March, 2026
  • Received 19 September 2025
  • Revised 13 November 2025
  • Accepted 14 December 2025
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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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