THz Aqueous Photonics and Beyond

Three of four states of matter: solid, gas, and plasma have been used for THz wave generation for decades. However, 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. Liquids have a high molecular density and a relatively low ionization threshold, meaning that light over a certain area will interact with many more molecules than an equivalent cross-section of gases and will generate more electrons. This makes liquids potential candidates for the generation of THz waves.