Terahertz pulse radiation from argon clusters.

The characteristics of THz pulse radiation from argon clusters irradiated with intense femtosecond laser pulses have been investigated. The average power of the THz pulses radiated from argon clusters is approximately 40 times greater than that from argon gas. The enhancement of the THz radiation originates from large laser absorption by the clusters. The polarization state and the angular distribution of the power of the THz pulses show no dependence on laser polarization, which suggests that the radiation originates from laser-induced charge separation along the laser propagation direction.