Theoretical study of terahertz generation from atoms and aligned molecules driven by two-color laser fields

We study the generation of terahertz (THz) radiation from atoms and molecules driven by an ultrashort fundamental laser and its second harmonic field by solving time-dependent Schrödinger equation. The simulations show that the initial wave-packet and its subsequent acceleration in the laser field, and rescattering with long-range Coulomb potential play key roles on THz generation. We also present the dependence of the optimal phase delay and yield of terahertz radiation on the laser intensity, wavelength, duration, the ratio of two-color laser components, and against the molecular alignment.