>mJ terahertz radiation sources from intense laser-foil interactions

We have systematically studied strong THz radiation from solid targets driven by relativistic femtosecond and picosecond laser pulses. The THz generation is due to coherent transition radiation of relativistic laser-driven electron beams when they pass the solid-vacuum boundary. The THz radiation with pulse energy of >mJ has been observed with picosecond pulses. Such high energy THz pulses can not only trigger various nonlinear dynamics in matter, but also open up a new research field of relativistic THz optics.