Using quick laser pulses, the scientists are able to fundamentally change the electronic properties of the non-conducting quartz glass that behaved though briefly for a second as a metal and a conductor. Generally, quartz glass does not conduct electric current like an insulator.
The study was published in the journal Physical Review Letters and Japan’s Tsukuba University was a research partner. With ultra-short laser pulses, however, the electronic properties of glass can be fundamentally changed in a split second.
“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 Vienna University of Technology researcher Christoph Lemell. Transistors usually work on a time scale of picoseconds (10^-12 seconds), laser pulses could switch electric currents a thousand times faster.