The World’s Fastest Nano-Optical Shutter
Roland Piquepaille writes " Physicists from several U.S. labs have clocked the transition of vanadium dioxide nanoparticles from a transparent to a reflective, mirror-like state, at less than 100 femtoseconds (a tenth of a trillionth of a second). According to this Vanderbilt University report, this effect has a size limit: "it does not occur in particles that are smaller than about 20 atoms across (10 nanometers)." This opens the door — if I can say so — to windows that are transparent at low temperatures and block out sunlight when the temperature rises. But other applications are possible, such as nanosensors which could measure the temperature at different locations within human cells, or "ultrafast" optical switches which could be used in communications and optical computing. Read this overview for more details, references and a surprising nanoscale image of Don Quixote and Sancho Panza."
April 9th, 2005 at 2:19 PM
Binary Dipole High K Dieletrics – Ferroelectric
Materials are known to be able to retain optical switching properties and non volatile polarities to 3.8 nanometer cell sizes while being able to change binary dipole states at less than 160 picoseconds.
April 10th, 2005 at 5:47 AM
Doesn't sound too useful for switches
100 femtoseconds is a pretty fast switch time, but it is activated by temperature, changing which takes considerably longer. Heating is doable with a laser pulse. How fast would the particle heat up? Cooling sounds more difficult; the heat would need to radiate away somehow – a pretty slow process. The result is a kind of a "instant on – slow off" switch.
April 10th, 2005 at 1:26 PM
Photon Induced Electric Field Poling
Sir, NO heat or cooling involved ??