Increased energy of THz waves from a cluster plasma by optimizing laser pulse duration

Abstract

We have investigated the generation of terahertz (THz) waves from an argon cluster plasma produced by laser pulses of various durations. THz energy depends on laser pulse duration and reaches a peak at a pulse duration of ∼250 fs. This dependence of THz energy on laser pulse duration is attributed to the plasma density produced by the rising edge of the pulse. By irradiating clusters with collinear double laser pulses, we demonstrate that the THz energy can be increased by controlling the plasma density. Optimizing the delay time of the collinear double laser pulses increases the THz energy by ∼2.5 times that with simultaneous irradiation of collinear double laser pulses.