Changing glass into metal, with the help of lasers
Scientists at the Vienna University of Technology found a way to turn quartz glass into metal — if only for a split second.
Using quick laser pulses, the scientists are able to fundamentally change the electronic properties of the non-conducting quartz glass and allow the material to briefly behave as a metal and a conductor.
“The laser pulse is an extremely strong electric field, which has the power to dramatically change the electronic states in the quartz,” Georg Wachter, theoretical physicist at the Vienna University of Technology said. “The pulse can not only transfer energy to the electrons, it completely distorts the whole structure of possible electron states in the material.”
The change in state may be short, but the scientists believe that transistor technology can take advantage of that moment. Once the laser pulses are applied, the change in state from glass to metal is found to happen within femtoseconds — one millionth of one billionth of a second.
In the transistors we are using today, a large number of charge carriers moves during each switching operation, until a new equilibrium state is reached, and this takes some time. The situation is quite different when the material properties are changed by the laser pulse. Here, the switching process results from the change of the electronic structure and the ionization of atoms. “These effects are among the fastest known processes in solid state physics”, says [associate professor at the Vienna University of Technology] Christoph Lemell. Transistors usually work on a time scale of picoseconds (10^-12 seconds), laser pulses could switch electric currents a thousand times faster.