New technology developed by researchers at the Massachusetts Institute of Technology and Purdue University could stave off the demise of the humble incandescent light bulb.
The scientists, who detailed their findings in the journal Nature Nanotechnology, developed a bulb with a thin metal filament — the same configuration used since the late 19th century.
Although those bulbs emit a warm glow compared to the harsh light of fluorescent bulbs, they lose most of their energy in the form of heat and prompted recent efforts to replace incandescent bulbs with more energy efficient alternatives.
Unlike conventional incandescent bulbs, however, the MIT and Purdue researchers surrounded the filament with a structure made of thin photonic crystal.
The crystal allows the visible wavelengths to pass through, but it acts like a mirror to infrared waves and directs them back toward the filament — gradually recycling the unwanted heat emissions into more light.
“It recycles the energy that would otherwise be wasted,” said MIT physics professor Marin Soljačić.
The technology could eventually increase the bulbs' luminous efficiency — which accounts for the response of the human eye to light — well beyond that of even fluorescent or LED bulbs.
The principle could also apply to other energy conversion technologies.
"The ability to control thermal emissions is very important," Soljačić said. "That’s the real contribution of this work."