A new Ultra-fast water-based switch with unprecedented speed

Laser controls the ultra-fast liquid switch.


Ultra-fast switches are essential devices for basic research and technological development. Circuits are the foundation for all computer and smartphone activities. The speed of a computer’s operation is determined by how quickly a component can transition between zero and one. Electrical switching is made feasible by semiconductors, which are used in modern computers.

German researchers at Ruhr University Bochum have created a water-based switch that operates extremely quickly. Within less than a trillionth of a second (10–12 seconds), a brief but intense laser pulse transforms water into a conductive state, which acts almost like a metal. This makes it faster than the known current quickest semiconductor switching speed.

Claudius Hoberg from the Ruhr Explores Solvation Cluster of Excellence RESOLV and his colleagues have unveiled a possible novel approach to water-based circuits. The water in which the researchers had dissolved iodide ions – salt water, in other words – is fanned out by a custom-made nozzle so that it streams as a flattened jet with a thickness of only a few micrometers.

Then, this water jet is passed a brief yet potent laser pulse. The laser causes the water to abruptly become conductive at terahertz frequencies, exhibiting properties akin to those of a metal when it releases electrons from the salt that is dissolved in it. The water functions as an incredibly quick switch due to the laser pulse’s brief (10–14 seconds) length.

Claudius Hoberg said“A speed of 10-12 seconds was observed in the terahertz range. A second laser probes the state of the water.”

Journal Reference:

  1. Adrian Buchmann, Claudius Hoberg, Fabio Novelli: An ultra-fast liquid switch for terahertz radiation, in APL Photonics, 2022, DOI: 10.1063/5.0130236
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