Picosecond terahertz pump–probe realized from Chinese terahertz free-electron laser
Wang Chao1, 2, Xu Wen1, 3, †, Mei Hong-Ying4, 1, Qin Hua5, Zhao Xin-Nian1, 2, Wen Hua1, 2, Zhang Chao1, Ding Lan3, Xu Yong6, Li Peng6, Wu Dai6, Li Ming6
       

Autocorrelation measurement of THz pulses of the CTFEL at three different frequencies. Together with Fourier transformation of these data, we can determine the width of THz pulses in both time- and frequency-domains.