Dr. Gregory Vieux Profile

Dr. Gregory Vieux

at Univ of Strathclyde

SPIE Involvement:

Author

Publications (23)

Proceedings Article | 23 October 2023 Paper

Filament-mediated disruption of laser propagation

C. Stacey, A. Wishart, C. Stace, H. White, C. Percy, K. Rigby, G. Vieux, D. Jaroszynski

Proceedings Volume 12739, 1273904 (2023) https://doi.org/10.1117/12.2673960

KEYWORDS: Modeling, Femtosecond phenomena, Zemax, Pulsed laser operation, Plasma

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Proceedings Article | 18 April 2021 Presentation

Enhanced scattering from a locally produced transient plasma grating in a plasma-based amplifier

Gregory Vieux, Silvia Cipiccia, Gregor Welsh, Sam Yoffe, Felix Gaertner, Matthew Tooley, Bernhard Ersfeld, Enrico Brunetti, Bengt Eliasson, MinSup Hur, Joao Dias, Thomas Kuehl, Dino Jaroszynski

Proceedings Volume 11778, 117780L (2021) https://doi.org/10.1117/12.2595297

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The increasing demand for high laser powers is placing huge demands on current laser technology. This is now reaching a limit, and to realise new areas of research promised at high intensities, new cost-effective and technically feasible ways of scaling up the laser power and controlling its optical characteristics are required. It is likely that ultra-compact, time-dependent, plasma-based amplifiers and optical elements (such as mirrors, polarisers, waveplates, etc.) will be required to reach powers exceeding tens of petawatts and possibly exawatts, and to manipulate the laser beams. Plasma is a robust optical medium as it is broken-down and can sustain extremely high electric fields. Plasma-based optical elements will most likely require the production of transient plasma gratings (TPGs), which take advantage of the ponderomotive force of the beat of at least two laser pulses. To create an amplifier, the TPG is formed through the action of the beat wave of a pump and seed pulse, which has a phase velocity satisfying the conditions for energy and momentum conservation of the three waves, where the third wave is a Langmuir or ion acoustic wave. Other optical elements will normally require static TPGs produced by degenerate driver pulses. Here we present the results of an experimental campaign conducted at the Central Laser Facility, where we have studied chirped pulse Raman amplification at high intensities. We have used a relatively long duration, frequency chirped, pump pulse to limit the growth of noise amplification, while ensuring amplification of the short seed pulse. We show that by changing the sign of the frequency chirp of the pump, the measured back-scattered and amplified seed energies change significantly. A negative chirp leads to a strong reduction in scattering from thermal density fluctuations, but seed amplification saturates. In contrast, for a positive frequency chirp, scattered energy continues to increase with increasing plasma density, without showing any sign of saturation, for the range of densities studied. From simulations we attribute this observation to the production of a local, long-lived, static TPG that continues to scatter the pump pulse long after it has passed. We will discuss the specific conditions that should be satisfied to produce such a grating. The ability to produce and maintain robust TPGs may provide a breakthrough in technologies for manipulating, reflecting and compressing ultra-intense laser pulses.

Proceedings Article | 18 April 2021 Presentation + Paper

Investigations into the volume plasma density grating waveplate

George Holt, Gregory Vieux, Bernhard Ersfeld, Samuel Yoffe, James Feehan, Enrico Brunetti, Min Sup Hur, Dino Jaroszynski

Proceedings Volume 11778, 117780M (2021) https://doi.org/10.1117/12.2595298

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Proceedings Article | 14 May 2019 Presentation

Chirped pulse Raman amplification in plasma (Conference Presentation)

Gregory Vieux, Silvia Cipiccia, Gregor Welsh, Sam Yoffe, Matthew Tooley, Craig Picken, Graeme McKendrick, Felix Gaertner, Enrico Brunetti, Bengt Eliasson, Bernhard Ersfeld, MinSup Hur, John Farmer, Joao Dias, Thomas Kuehl, Alexander Pukhov, Dino Jaroszynski

Proceedings Volume 11036, 1103604 (2019) https://doi.org/10.1117/12.2522976

KEYWORDS: Plasma, Raman spectroscopy, Laser applications, Laser amplifiers, Backscatter, Raman scattering, Scattering, Capillaries, Picosecond phenomena

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Proceedings Article | 14 May 2019 Presentation

Raman amplification in plasma (Conference Presentation)

Samuel Yoffe, Gregory Vieux, Bernhard Ersfeld, Enrico Brunetti, Adam Noble, Remi Lehe, Jean-Luc Vay, Teyoun Kang, MinSup Hur, Dino Jaroszynski

Proceedings Volume 11036, 1103605 (2019) https://doi.org/10.1117/12.2522500

KEYWORDS: Raman spectroscopy, Plasma, Particles, Laser development, Laser systems engineering, Laser damage threshold, Solid state lasers, Solid state physics, Optical amplifiers, Backscatter

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There is significant international effort focussed on developing ultra-high-power systems for next-generation laser facilities, such as the Extreme Light Infrastructure (ELI). Existing amplification methods are based on chirped-pulse amplification (CPA). However, the low damage threshold of conventional solid-state optics results in very large amplifiers and compressors. To overcome this challenge, we use stimulated Raman backscattering of a long pump laser in plasma to provide amplification for a low intensity seed pulse. Plasma has the advantage that it is already a broken down medium and therefore field intensities are not constrained as they are in conventional laser amplifiers. This offers the potential to reduce the size and cost of these devices significantly, while providing a possible route to reach exawatt powers, which will enable investigation of extremely high field physics. Despite its advantages, efficient Raman amplification has not yet been demonstrated experimentally. Efficiencies are limited to only a few percent for seed energies of a few mJ, in contrast with theoretical predictions. Several phenomena lead to saturation or inhibit the amplification process – such as detuning, wavebreaking and particle trapping – depending on the amplification regime. Amplification is therefore highly sensitive to the conditions and parameters used. Raman amplification experiments are challenging, and careful planning is required to ensure that controlled and sustained amplification can take place. Numerical simulation is an essential ingredient to this preparation yet, like the experiments themselves, this is not a trivial task. The amplification process takes place over several millimetres, while structures on the short beat wavelength of the lasers need to be adequately resolved. Since particle kinetic effects are also important, a large number of particles are required. Simulation of the entire domain therefore requires significant computing resources, and therefore many investigations are only performed in 1-dimension. Moreover, the long propagation times involved allow numerical artefacts from processes such as grid heating or numerical dispersion to become significant. These can become pathological and artificially seed or disturb the amplification process. Using state-of-the-art numerical techniques, we investigate the amplification of low- and high-intensity seed pulses in plasma, and compare their amplification growth rates and efficiencies with experimental results obtained by our group. The use of a chirped pump laser pulses is discussed and compared.