Recent Development on THz Aqueous Photonics

Until now, the demonstration of THz wave generation from liquid sources was conspicuously absent, especially from liquid water due to its infamously strong absorption characteristics in the THz regime. It is reasonable to expect that liquids might have unique properties if they could be harnessed as THz sources [1]. Liquids have a high density, close to that of solids, meaning that light over a certain area will interact with many more molecules than an equivalent cross-section of gases. This makes liquids potential candidates for the study of high-energy-density plasma. Now we have completed the last piece of the matter-phase puzzle for THz sources. Broadband THz pulses generated from liquid water have been measured in a time-domain system [2]. New physics will be developed to fully characterize this process in liquids, especially in water and related materials, to support new THz wave science, technology and applications.