In this letter, we describe a coherent subpicosecond terahertz (THz) spectroscopy system based on non-resonant optical rectification for the generation of THz radiation. We studied the two-photon absorption (TPA) of ZnTe induced by femtosecond laser pulses via THz generation, and its influence on the generation of THz radiation. Experimental results demonstrated that the intensity of pump beam against TPA must be traded off to get an optimum generation of THz radiation. As an example, we measured absorption spectrum of water vapor by time-domain spectroscopy (TDS) in the frequency range from 0.5 to 2.5 THz with a high overall accuracy.
© 2005 Chinese Optics Letters
(190.3270) Nonlinear optics : Kerr effect
(190.4180) Nonlinear optics : Multiphoton processes
(190.7110) Nonlinear optics : Ultrafast nonlinear optics
(300.1030) Spectroscopy : Absorption
(320.5390) Ultrafast optics : Picosecond phenomena
Liying Lang, Qirong Xing, Shuxin Li, Fanglin Mao, Lu Chai, and Qingyue Wang, "Experimental study on terahertz radiation," Chin. Opt. Lett. 2, 677-679 (2004)