UNLIKE OPTICAL SPECTROSCOPY, terahertz timedomain spectroscopy allows the engineer to measure complex amplitude instead of the intensity of the terahertz probe. Recently, a terahertz generation and detection setup based on a pump-probe scheme was presented by An-Tao Chen from the University of Washington, Li-Shuang Feng from Beihang University in Beijing, Xiang-Jun Xin and Chong-Xiu Yu from Beijing University of Posts and Telecommunications, and Zhen Zhou, who is connected to all three of these institutions.
The researchers successfully generated and detected terahertz pulses using the nonlinear optical rectification of high-power femtosecond laser pulses and electro-optic sampling. For their setup, they obtained a 3-THz available spectrum range. To test the use of terahertz pulses for spectroscopy, the engineers measured the absorption spectrums of water in both air and dry nitrogen. If the setup's signal-to-noise ratio is increased, wider spectrum range can be obtained. See "Terahertz Generation and Detection Setup Based on Pump-Probe Scheme," Microwave And Optical Technology Letters, July 2009, p. 1617.