Abstract
The researches of THz spectra and applications have continued for more than 20 years. Most topics are focused on the linear spectra about THz absorption and transition of specific materials or physical phenomena. The lack of research about transient carrier dynamics leads us to set up an ultrafast time-resolved optical pump-THz probe system. The system can measure free carriers very sensitively by the absorption so we can detect the carrier number with time evolution by incident optical pump at different moment. That is how the ultrafast optoelectronic response can be gotten. Because of the merit of time-resolved THz spectra, we can get much more information than linear spectra, like carrier lifetime in LED, MOS, QW, and QD etc, quantum efficiency, or even phonon dynamics. Those knowledge will improve the efficiency and quality of optoelectric devices intrinsically.