Strong terahertz radiation from a liquid-water line

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

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66 Citations (Scopus)
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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.

Original languageEnglish
Article number014005
Number of pages8
JournalPhysical Review Applied
Issue number1
Publication statusPublished - 2 Jul 2019


  • terahertz radiation
  • liquid water
  • generation


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