Switching Quartz Conductivity with Laser Pulses
Quartz glass is not an unfamiliar material for most of us, though we likely do not consider its electrical properties. Under normal circumstances, it is an insulator, but researchers at the Vienna University of Technology and Tsukuba University have found that it can be made into a conductor. The catch is that a femtosecond laser pulse is required.
For years now, femtosecond laser pulses have been in used to measurement quantum effects in small particles, because at such a small time scale of 10-15 seconds, even quantum mechanics can be caught. What this new research demonstrates is that these pulses can also be used to trigger significant changes in a material, and thanks to computer simulations, we now know when. When the pulse strikes the quartz, it pumps electrons bound to the oxygen atoms to another atom. This allows them to behave like free electrons and the electric field of the light then drives them in one direction, creating a current. This current only exists for a very short amount of time, but does persist a little after the pulse has faded.
This process is among the fastest in solid state physics, even beating the speed of transistors, which operate on picoseconds; a thousand times slower. Next the researchers want to test other materials and potentially find one that allows a more efficient use of the effect.
Source: Vienna University of Technology