Laser makes light bulbs super-bright

Posted by Emma Woollacott

Rochester, NY - Ordinary incandescent light bulbs can be made super-efficient using a laser process, say optics researchers at the University of Rochester.


The process could make a light as bright as a 100W bulb, but which requires less electricity than a 60W lamp, is cheaper and radiates a more pleasant light than a fluorescent bulb can.


"We've been experimenting with the way ultra-fast lasers change metals, and we wondered what would happen if we trained the laser on a filament," said Chunlei Guo, associate professor of optics at the University of Rochester. "We fired the laser beam right through the glass of the bulb and altered a small area on the filament. When we lit the bulb, we could actually see this one patch was clearly brighter than the rest of the filament, but there was no change in the bulb's energy usage."


The key to creating the super-filament is an ultra-brief, ultra-intense beam of light called a femtosecond laser pulse. The laser burst lasts only a few quadrillionths of a second, but forces the surface of the metal to form nanostructures and microstructures that dramatically alter how efficiently light can radiate from the filament. Despite the intensity involved, the femtosecond laser can be powered by a simple wall outlet, meaning that when the process is refined, implementing it to augment regular light bulbs should be relatively simple.


"We knew it should work in theory," says Guo, "but we were still surprised when we turned up the power on this bulb and saw just how much brighter the processed spot was."


In addition to increasing the brightness of a bulb, Guo's process can be used to tune the color of the light as well. Guo's team has even been able to make a filament radiate partially polarized light, which until now has been impossible without special filters that reduce the bulb's efficiency. The team is now working to discover what other aspects of a common light bulb they might be able to control.


The findings will be published in an upcoming issue of the journal Physical Review Letters.