Terahertz wave rectification in a ferroelectric triglycine sulfate single crystal

The effect of optical rectification (OR) in the terahertz range (THz rectification, TR) is experimentally demonstrated. The effect consists of generating a DC voltage on the faces of a ferroelectric triglycine sulfate (TGS) single crystal under the action of pulsed radiation with a frequency of 1.57 and 1.96 THz and an electric field strength per pulse of 1.3 and 1.5 MV/m, respectively. The FLARE FELIX free-electron laser system (Radboud University, The Netherlands) was used as a THz radiation source. The TR effect makes it possible to directly determine the nonlinear susceptibilities of media (including those under conditions of strong absorption) without any reference or optical channel calibration and also without the need of Fourier transform.