Intense terahertz emission from argon clusters irradiated by 60 mJ femtosecond laser pulse

THz pulse emission from argon clusters irradiated by intense femtosecond laser pulses have been investigated. Intense THz pulses emitted from argon clusters have been obtained without employing any biasing electric field or frequency mixing method. The energy of THz pulses is almost three orders of magnitude larger than that from air plasma. The enhancement of the THz radiation originates from large laser absorption by the clusters.