Abstract
Relativistic electron-positron plasmas are believed to have an important role in the energetic phenomena
in the universe, in the form of collimated jets or relativistic flow from pulsars and black-holes.
Development of ultra-intense lasers are making possible to create this unique entity on the earth and
open up an experimental frontier of astrophysics. Here presented are the review on the relativistic
electron-positron plasma generation via Bethe-Heitler process by using high power lasers. It was
demonstrated that more than 1012/kJ of pair creation per laser energy was possible and formation of the
relativistic pair plasmas, which make it possible to investigate the collisionless shock in the laboratory, is
expected by up-coming large laser facility with 10-kJ output energy. Relevant experiment at Osaka
University is also reported.
