Integrated system of traditional THz time-domain spectroscopy and asynchronous optical sampling

Terahertz time-domain spectroscopy (THz-TDS) system, as a new means of spectral analysis and detection, plays an increasingly pivotal role in basic scientific research. However, owing to the long scanning time of the traditional THz-TDS system and the complex control of the asynchronous optical scanning (ASOPS) system, which requires frequent calibration, we combine traditional THz-TDS and ASOPS systems to form a composite system and propose an all-fiber trigger signal generation method based on the time overlapping interference signal generated by the collinear motion of two laser pulses. Finally, the time-domain and frequency-domain spectra are obtained by using two independent systems in the integrated systems. It is found that the full width at half maximum (FWHM) of the time-domain spectra and the spectral width of the frequency-domain spectra are almost the same, but the sampling speed of the ASOPS system is significantly faster than that of the traditional THz-TDS system, which conduces to the study of the transient characteristics of substances.