arXiv subjects

Victor Koltalo

Publications and source records attributed to Victor Koltalo.

3 recordsLinked to original sources

arXiv2026

Sub-2-Cycle, Terawatt Pulses via Double-Stage Multi-Pass Cell Compression of an Yb Laser

We report a terawatt-class, sub-2-cycle post-compressed Yb-based laser system operating at kHz repetition rate. 18 mJ, 400 fs pulses delivered at 1 kHz by a commercial Yb:YAG laser are spectrally broadened and temporally compressed in a double-stage multi-pass cell setup featuring an argon-filled Herriott-type cell followed by a helium-filled array-type cell, achieving an overall compression factor of 65. The resulting compressed pulses are measured to have 6.2 fs duration (1.8 optical cycles at 1030 nm) and 12.5 mJ energy, corresponding to 1.4 TW effective peak power. To the best of our knowledge, this constitutes the highest peak power reported to date for a few-cycle, kHz-repetition-rate, post-compressed Yb laser system. Focused intensity measurements yield a normalized vector potential of a0 = 3.0, confirming the applicability of this light source for laser wakefield acceleration.

physics.optics↗

arXiv2025

Compact, intense attosecond sources driven by hollow Gaussian beams

High-order harmonic generation (HHG) enables the up-conversion of intense infrared or visible femtosecond laser pulses into extreme-ultraviolet attosecond pulses. However, the highly nonlinear nature of the process results in low conversion efficiency, which can be a limitation for applications requiring substantial pulse energy, such as nonlinear attosecond time-resolved spectroscopy or single-shot diffractive imaging. Refocusing of the attosecond pulses is also essential to achieve a high intensity, but difficult in practice due to strong chromatic aberrations. In this work, we address both the generation and the refocusing of attosecond pulses by sculpting the driving beam into a ring-shaped intensity profile with no spatial phase variations, referred to as a Hollow Gaussian beam (HGB). Our experimental and theoretical results reveal that HGBs efficiently redistribute the driving laser energy in the focus, where the harmonics are generated on a ring with low divergence, which furthermore decreases with increasing order. Although generated as a ring, the attosecond pulses can be refocused with greatly reduced chromatic spread, therefore reaching higher intensity. This approach enhances the intensity of refocused attosecond pulses and enables significantly higher energy to be delivered in the driving beam without altering the focusing conditions. These combined advantages open pathways for compact, powerful, tabletop, laser-driven attosecond light sources.

physics.optics↗

arXiv2024

Energy scaling in a compact bulk multi-pass cell enabled by Laguerre-Gaussian single-vortex beams

We report pulse energy scaling enabled by the use of Laguerre-Gaussian single-vortex ($\text{LG}_{0,l}$) beams for spectral broadening in a sub-40 cm long Herriott-type bulk multi-pass cell. Beams with orders ${l= 1-3}$ are generated by a spatial light modulator, which facilitates rapid and precise reconfiguration of the experimental conditions. 180 fs pulses with 610 uJ pulse energy are post-compressed to 44 fs using an $\text{LG}_{0,3}$ beam, boosting the peak power of an Ytterbium laser system from 2.5 GW to 9.1 GW. The spatial homogeneity of the output $\text{LG}_{0,l}$ beams is quantified and the topological charge is spectrally-resolved and shown to be conserved after compression by employing a custom spatio-temporal coupling measurement setup.

physics.optics↗