Turning on LEDs

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They use nanoscale engineering to etch special features into a semiconductor chip, near the active area of material that produces the photons. When photons are emitted, they can travel in any direction -- but it’s only the ones at a 90-degree angle to the surface of the chip that make it out of the chip; the others are reabsorbed. The etched features, called photolattices, are patterns of lines whose spacing is similar to the wavelength of the light they’re dealing with. Hence, the lattices act like lenses, diverting more of the photons out of the chip, thereby improving the external efficiency.

It’s also possible, though not yet proven, Simmons says, that they’re improving the internal efficiency at the same time. It may be that the photolattices, by making it impossible for photons to exist in certain places in the material, are causing more of the photons that are produced to be emitted in the right direction in the first place.

The energy bill passed by Congress last summer included authorization for up to $50 million in research funding for the technology over each of the next seven years. But whether Congress will actually appropriate the funds is anybody’s guess.

Nevertheless, Simmons is excited about the possibilities. The real test, he emphasizes, will be whether or not consumers warm to a new type of lighting. “What we’re waiting for -- the next big impact -- is to start seeing use in the home,” Simmons says.