A direct comparison between terahertz time-domain spectroscopy and far-infrared Fourier transform spectroscopy

We perform a comprehensive comparison between terahertz (THz) time-domain spectroscopy and conventional far-infrared Fourier transform spectroscopy, including radiation source, detector, signal to noise ratio, bandwidth, availability, applications, and their own uniqueness. In terms of signal to noise ratio, THz time-domain spectroscopy is advantageous at low frequencies under 3 THz, while Fourier transform spectroscopy works better at frequencies above 5 THz. In addition, we provide a detailed discussion of the unique features of THz time-domain spectroscopy and its application to dynamic and time-resolved processes.