Principle of Terahertz Time-Domain Spectroscopy

In this work, the detection of terahertz (THz) pulse via different schemes of THz time-domain spectroscopy (THz-TDS), including electro-optic sampling (EOS) and photoconductive sampling (PCS), has been reviewed by insisting on its principles and characteristics. Furthermore, four developments of THz-TDS, i.e. THz air-breakdown/biased coherent detection (THz-ABCD), THz-radiation-enhanced emission of fluorescence (THz-REEF), single-shot THz-TDS, and THz asynchronous optical sampling (THz-ASOPS) have also been introduced.