Ultrahigh intensity lasers have been developed for the exploration of strong field physics in a number of institutes around the world. At Center for Relativistic Laser Science of Institute for  Basic Science two PW laser beamlines have been utilized for investigating relativistic laser- matter interactions, and one of them has been upgraded recently to a 20 fs, 4 PW laser [1]. With  the PW lasers we succeeded in generating multi-GeV electron beams and collisionless  electrostatic shock. We plan to carry out the Compton backscattering to generate MeV gamma- rays from the interaction of a GeV electron beam and another laser beam, offering an  opportunity to measure strong field QED effects. In addition, we plan to carry out the investigation of laboratory astrophysics, such as plasma instabilities, shock acceleration, and magnetic reconnection.

[1] J. H. Sung et al., “4.2 PW, 20 fs Ti:Sapphire Laser at 0.1 Hz,” Opt. Lett. 42, 2058 (2017).