Filament efficiency

Researchers at the University of Rochester, New York, have developed a laser-based process that could reduce the power consumption of incandescent light bulbs.

The process could make a light as bright as a 100W bulb consume less electricity than a 60W bulb, while remaining far cheaper and radiating a more pleasant light than a fluorescent bulb.

The laser process creates an array of nano- and micro-scale structures on the surface of a regular tungsten filament - the wire inside a light bulb - and these structures make the tungsten become far more effective at radiating light.

'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.

'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 super-filament was created using a brief, intense pulse of light from a femtosecond laser. 

During its brief burst, the surface of the metal formed the nanostructures and microstructures that dramatically altered how efficiently light radiated from the filament.

Guo's team has even been able to make a filament radiate partially polarised light, which until now has been impossible to do without special filters that reduce the bulb's efficiency.

By creating nanostructures in tight, parallel rows, some light emitted from the filament becomes polarised.

The team is now working to discover what other aspects of a common light bulb they might be able to control.

Fortunately, despite the high intensity involved, the femtosecond laser can be powered by a simple wall outlet.

This means that when the process is refined, implementing it to augment regular light bulbs should be relatively simple.