Generation of Powerful Phase-Controlled Single-Cycle Terahertz Pulses for Pump-Probe Experiments

A pump-probe experimental system was developed that delivers single-cycle terahertz (THz) pulses with energies of up to 10 $$\mu$$ J optically synchronized with laser pulses in the near-infrared range (1030 nm) with a duration of 25 fs. The THz pulses were generated in two-color laser-induced plasma in atmospheric air with mid-infrared laser radiation (3.9 $$\mu$$ m wavelength) and its second harmonic with a controlled phase difference between them. We measured the waveform and polarization of the THz pulse, and the size of the THz beam focal waist. The ability to switch the orientation of the THz electric field vector to the opposite direction was demonstrated. The developed experimental pump-probe setup can be used to study the properties of materials exposed to THz pulses with peak field strength of several MV/cm.