In THz TDS, a femtosecond laser pulse excites a photoconductive antenna or nonlinear crystal to generate a short burst of THz radiation. This pulse is then directed at the sample of interest. The transmitted or reflected THz pulse is detected, often using electro-optic sampling or photoconductive antennas. The time-domain waveform is recorded and subsequently converted to the frequency domain via Fourier transformation, providing spectral information about the sample.
