Seminar : « Strong field physics research performed with a multi-PW laser ».

Professor who invites : Professeur François Légaré

Conférencier : Professeur Chang Hee Nam, Dept. of Physics and Photon Science, GIST; Center for Relativistic Laser Science, IBS, Korea

Abstract:  At Center for Relativistic Laser Science (CoReLS) of Institute for Basic Science (IBS), petawatt lasers have been developed for the investigations of strong field physics. We constructed a 20 fs, 4 PW Ti:Sapphire laser in 2017 [1] and achieved the record-breaking laser intensity of 10²³ W/cm² in 2021 [2]. This multi-PW laser has been applied to the investigations of superintense laser-matter interactions, laser-driven charged particle acceleration, and strong field quantum electrodynamics (QED). With the PW laser the acceleration of protons and ions was investigated using ultrathin solid targets. Radiation pressure acceleration of protons over 90-MeV energy was demonstrated by applying a PW laser to a 15-nm polymer target [3]. By applying PW laser pulses to near critical density targets made of carbon nanotubes, strong hard x-ray flashes were obtained [4]. Furthermore, by driving micro-structured ultrathin polymer targets with the multi-PW laser, we could accelerate protons to an energy over 110 MeV, thanks to the superb pointing stability and extremely good prepulse contrast of the PW laser. By applying the laser wakefield acceleration, we have produced multi-GeV electrons and used them for exploring nonlinear Compton scattering for the research of strong field QED phenomena [5], predicted to occur in astrophysical objects, such as supernova, magnetar and black hole. In this talk, after introducing the CoReLS PW laser, the strong field physics research program at CoReLS will be explained.

References:

[1] J. H. Sung et al., “4.2 PW, 20 fs Ti:Sapphire Laser at 0.1 Hz,” Opt. Lett. 42, 2058 (2017), https://doi.org/10.1364/OL.42.002058 .
[2] J. W. Yoon et al., “Realization of laser intensity over 10²³ W/cm²,” Optica 8, 630 (2021), https://doi.org/10.1364/OPTICA.420520 .
[3] I J. Kim et al., “Radiation pressure acceleration of protons to 93 MeV with circularly polarized petawatt laser pulses,” Phys. Plasmas 23, 070701 (L) (2016), https://doi.org/10.1063/1.4958654 .
[4] Y. Shou et al., “Brilliant femtosecond-laser-driven hard X-ray flashes from carbon nanotube plasma,” Nat. Photon. 17, 137 – 142 (2023), https://doi.org/10.1038/s41566-022-01114-8 .
[5] M. Mirzaie et al., “All-optical nonlinear Compton scattering performed with a multi-PW laser,” Nat. Photon. 18, 1212–1217 (2024), https://doi.org/10.1038/s41566-024-01550-8 .

Biography: Chang Hee Nam received his Ph. D. in plasma physics from Princeton University. After working at Princeton Plasma Physics Laboratory as a staff research physicist, he joined Korea Advanced Institute of Science and Technology (KAIST) and established Coherent X-ray Research Center for the investigation of attosecond science. After moving to Gwangju Institute of Science and Technology (GIST), he launched the Center for Relativistic Laser Science (CoReLS), a research center of Institute for Basic Science (IBS), for the exploration of strong field physics using femtosecond PW lasers. He is a fellow of American Physical Society and of Optica (formerly Optical Society of America).