Double pulse excitation for enhancing THz generation in liquid jets

We implement a double-pump technique to enhance THz energy generated in liquid jets. The dependence of the THz emission enhancement efficiency on the temporal delay between two collinear optical pulses is experimentally and theoretically investigated. To understand the physics of the process, we compare the cases of 200 fs and 300 fs pump pulses and reveal the advantage of using a pulse of optimal for a specific jet thickness duration for more efficient enhancement. We assume that in addition to the effective method of strong THz generation, double-pump can be a method of measuring the plasma channel lifetime.