This bulb uses photonic crystals and tungsten sheets to recycle heat. Researchers from MIT have developed a new incandescent bulb that's more energy efficient 
(via MIT, Photo from Nature)
As our society becomes more energy-conscious more and more people are saying goodbye to the traditional incandescent light bulbs. Many retailers, like IKEA, have even stopped selling them offering the LED or fluorescent bulbs instead. The issue with the standard bulbs is they use a lot of energy since they generate a huge amount of heat in addition to light. To give you an idea, the wire you can see through the bulb (tungsten filament) can reach up to 4,940 degrees Fahrenheit. Still, some people prefer the standard since it's less harsh than some of the substitutes. So how can people use their favorite bulb without wasting energy? One MIT team may have the solution.
A team of researchers from MIT announced they have developed a method to make incandescent lights more energy efficient. This new bulb retains the filament in the center, but is now surrounded with a new type of crystal filter which sits around the filament. Visible light passes through the filter, but infrared wavelengths of light are reflected back towards the filament. The infrared light and the heat that comes with it, is then reabsorbed by the filament and re-emitted as visible light in a constant cycle. In other words, the bulb powers itself on its own waste heat. This improved the efficiency of the bulb to 6.6%, triple that of traditional light bulbs.
The crystal filter, called photonic crystals, were created with millimeter thick sheets of glass and 90 alternating layers of tantalum oxide and silicon dioxide. The research team used this mix because it reflects infrared light but not visible photons. Along with this, the team redesigned the bulbs tungsten filament. Instead of having the curly wire, a thin tungsten ribbon was folded back and forth creating a thin sheet. Electrons follow a long circuitous path and heat up the metal to make it glow. Since the tungsten sheet has a larger surface area, it's easier for the metal to absorb more infrared photons reflected by the crystals.
Before you head out to your local hardware store to grab some, know that these bulbs aren't available yet. They're still a proof of concept, so don't expect to see them at retailers anytime soon. The researchers still have a lot to do before it's ready for consumers, but the prototype is proving to be successful. Hopefully, it won't take too long for the bulbs to hit the market.
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