Contribution of photocurrent mechanism and influence of plasma length in THz generation by two-color laser induced plasma

The contribution of the photocurrent mechanism has been investigated in terahertz (THz) generation in laser-induced gas plasma. This study was done through comparing the THz amplitude for two phase differences (phi = 0, pi/2)between the fundamental pulse and its second harmonic. Our particle-in-cell simulation result showed that this mechanism played the most important role in the two-color regime with a low-frequency range. We also investigated the effect of the plasma channel length on generated THz amplitude, and it was found that THz amplitude would depend significantly on the plasma channel length. Published by AIP Publishing.