Ionization-Based Optical Structures for the Control of Short-Pulse Lasers

Pierre Michel | 21-LW-013

Project overview

The intensity of light from the highest-power lasers is limited by the size of the optics required to amplify, compress, transport, and focus a laser beam. Indeed, optics damage puts strict constraints on the laser-energy density that solid optics can sustain; this leads to enormous optics sizes and limits the maximum intensity that these lasers can achieve.

In this project, we investigated new types of diffractive optics based on mixtures of neutral gas and plasmas. The basic idea is to interfere laser beams in a gas near the ionization threshold, so that plasma is created in the constructive interference regions (i.e., the "bright" fringes of the interference pattern) while the destructive interference regions remain a neutral gas. The resulting refractive index modulation, due to the different indices in gas vs. plasma, effectively turns such structures into diffractive optics elements. We proposed several new types of optics based on this general concept: i) reflection gratings, which can act as mirrors of "pulse cleaners" to eliminate laser pre-pulse; ii) transmission gratings, as part of a new type of pulse compression scheme with the potential to achieve laser intensities orders of magnitude above what is currently feasible using solid-state optics; and iii) holographic lenses, to focus high-power lasers. We conducted laboratory experiments that demonstrated high-efficiency reflection gratings, paving the way for practical applications of our new concepts.

Mission Impact

This project has confirmed LLNL's position as a leader in the new area of plasma optics. This new, disruptive technology should enable a major step forward in the development of the next generation of high-power lasers for application ranging from compact particle accelerators to inertial fusion energy (IFE).

Publications, Presentations, and Patents

Edwards, M. R. and P. Michel. 2022. "Plasma Transmission Gratings for Compression of High-Intensity Laser Pulses." Physical Review Applied 18, 024026 (2022); doi: 10.1103/PhysRevApplied.18.024026.

Edwards, M. R. et al. 2022. "Holographic Plasma Lenses." Physical Review Letters 128, 065003 (2022); doi: 10.1103/PhsRevLett. 128.065003.

Edwards, M. R. et al. 2021. "Measuring the Optical Properties of Ionization Gratings in Air for Control of Femtosecond Lasers." Presentation, CLEO: Fundamental Science, San Jose, CA. May 2021.

Edwards, M. R. et al. 2020. "High-Intensity Bragg Reflection of a Femtosecond Laser via Ionized Structures in Air." Presentation, 62nd Annual Meeting of the APS Division of Plasma Physics, Virtual. November 2020.

Edwards, M. R. et al. 2021. "Diffractive Plasma Optics for Control of High-Power Femtosecond Beams." Presentation, 47th EPS Conference on Plasma Physics. Virtual. June 2021.

Edwards, M. R. et al. 2021. "Focusing High-Power Laser Pulses with Diffractive Plasma Lenses." Presentation, 63rd Annual Meeting of the APS Division of Plasma Physics. Pittsburgh, PA. November 2021.

Edwards, M. R. 2022. "Diffractive Plasma Optics for High-Power Lasers." Presentation, 50th Anomalous Absorption Conference, Skytop, PA, June 2022.

Edwards, M. R. 2022. "Diffractive Plasma Optics via Ionization for the Generation and Control of High-Power Laser Pulses." Presentation, 64th Annual Meeting of the APS Division of Plasma Physics. Spokane, WA. October 2022.

Edwards, M. R., and P. Michel. ROI: IL-13624 "Holographic Plasma Lenses."

M. R. Edwards and P. Michel. ROI: IL-13658 "Plasma Transmission Gratings for High-Intensity Laser Pulse Compression."

M. R. Edwards and P. Michel. ROI: IL-13730 "Gas and Plasma Final Optics for Inertial Fusion Energy Lasers."

M. R. Edwards and P. Michel. ROI: IL-13744 "Temporal Contrast Improvement for Short Pulse Lasers via Ionization Gratings."