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By illuminating a thin film of water with ultrashort laser pulses, physicists have demonstrated that liquid water can generate terahertz (THz) waves, which are currently being researched for applications such as wireless data transmission, industrial quality control, and high-resolution imaging with the capability for penetration.

The researchers, led by Xi-Cheng Zhang, the M. Parker Givens Professor at the University of Rochester's Institute of Optics in New York, as well as at Capital Normal University in Beijing and ITMO University in Saint Petersburg, Russia, have published a paper on the generation of THz waves from in a recent issue of Applied Physics Letters.

The result is surprising because bulk water is a strong absorber of light in the THz frequency range, and so for a long time it seemed very unlikely that liquid water could serve as a source of THz radiation. Researchers have previously shown, however, that water can emit light at other frequencies, including white light, and that water vapor can emit THz waves. The key to getting to generate THz waves, as the scientists show in the new study, is to use a very thin (less than 200 μm-thick) free-flowing film of water.

"Although it might be too early to predict any industrial or commercial applications for our work at this moment, I think it provides the last piece of the puzzle," Zhang told Phys.org. "Solid, gas, and plasma have been used to generate THz waves already, but not liquid. With liquid, especially water, four states of matter have now been used as THz sources."



Read more at: https://phys.org/news/2017-08-thought-impossible-scientists-liquid-thz.html#jCp

By illuminating a thin film of water with ultrashort laser pulses, physicists have demonstrated that liquid water can generate terahertz (THz) waves, which are currently being researched for applications such as wireless data transmission, industrial quality control, and high-resolution imaging with the capability for penetration.

The researchers, led by Xi-Cheng Zhang, the M. Parker Givens Professor at the University of Rochester's Institute of Optics in New York, as well as at Capital Normal University in Beijing and ITMO University in Saint Petersburg, Russia, have published a paper on the generation of THz waves from water in a recent issue of Applied Physics Letters.

The result is surprising because bulk water is a strong absorber of light in the THz frequency range, and so for a long time it seemed very unlikely that liquid water could serve as a source of THz radiation. Researchers have previously shown, however, that water can emit light at other frequencies, including white light, and that water vapor can emit THz waves. The key to getting liquid water to generate THz waves, as the scientists show in the new study, is to use a very thin (less than 200 μm-thick) free-flowing film of water.

"Although it might be too early to predict any industrial or commercial applications for our work at this moment, I think it provides the last piece of the puzzle," Zhang told Phys.org. "Solid, gas, and plasma have been used to generate THz waves already, but not liquid. With liquid, especially water, four states of matter have now been used as THz sources."

To read more, click here.