Recently Terahertz (THz) radiation from laser-produced plasmas has attracted much interest since plasmas can work at arbitrarily high laser intensity. We systematically investigate the generation of strong THz radiation from solid targets irradiated by ultraintense laser pulses with relativistic intensities exceeding 1018W/cm2.The experiments were performed with femtosecond and picosecond laser facilities respectively. The numerous energetic MeV fast electrons produced by the high-intensity laser pulses serve as the primary source of the THz radiation. When the forward fast electrons reach the target rear surface, THz radiation is induced via the mechanism of transition radiation. To enhance the THz radiation, a variety of techniques have been employed. These include increasing laser absorption through the use of a preplasma, fabricating nanostructures on the front surface of the target, optimizing the target thickness, applying a CH coating, and employing an additional laser pulse to ablate the target rear. The optimized energy of the terahertz pulses can reach the millijoule to hundreds of millijoules range, depending on the specific parameters of the driving laser pulses. Recently the peak power of the THz bursts driven by the fs PW laser system at Hairou reaches 2 TW. We have conducted preliminary studies exploring the new physics driven by the strong terahertz pulses, such as the excitation of phase transition of condensed matters, water dynamics, and THz-induced plasma.
 

Intense laser-plasma interactions, Terahertz radiation