Strong terahertz radiation from a liquid-water line

Zhang, Liang-Liang and Wang, Wei-Min and Wu, Tong and Feng, Shi-Jia and Kang, Kai and Zhang, Cun-Lin and Zhang, Yan and Li, Yu-Tong and Sheng, Zheng-Ming and Zhang, Xi-Cheng (2019) Strong terahertz radiation from a liquid-water line. Physical Review Applied, 12 (1). 014005. ISSN 2331-7019

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    Terahertz radiation generation from liquid water has long been considered impossible due to strong absorption. A few very recent works reported terahertz generation from water, but the mechanism is not clear and the efficiency demands to be enhanced. We show experimentally that strong single-cycle terahertz radiation with field strength of 0.2MVcm-1 is generated from a water line (or column) of approximately 200μm in diameter irradiated by a mJ femtosecond laser beam. This strength is 100-fold higher than that produced from air using single-color pumping. We attribute the mechanism to the laser-ponderomotive-force-induced current with the symmetry broken around the water-column interface. This mechanism can explain our following observations: the radiation can be generated only when the laser propagation axis deviates from the column center; the deviation determines its field strength and polarity; it is always p polarized no matter whether the laser is p or s polarized. This study provides a simple and efficient scheme of table-top terahertz sources based on liquid water.

    ORCID iDs

    Zhang, Liang-Liang, Wang, Wei-Min, Wu, Tong, Feng, Shi-Jia, Kang, Kai, Zhang, Cun-Lin, Zhang, Yan, Li, Yu-Tong, Sheng, Zheng-Ming ORCID logoORCID: and Zhang, Xi-Cheng;