Michael Kanellos 06 24 08, 4:55 AM

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Big-Assed LEDs: The Secret to Luminus’ Success

In the chip industry, the size of chips typically only goes one way: down. By exploiting the properties of Moore’s Law, manufacturers can shrink the size of the transistors that go into their semiconductors every two years and get chips that take up less space. Although manufacturers might add features and transistors, the size of their devices almost invariably shrinks at a steady pace. (Shrinking also makes them cheaper.)

Luminus Devices, the light emitting diode (LED) spin-out from MIT, however, has found that you can get interesting properties out of large chips. Rather than make small LEDs that might measure 1 millimeter a side and take up a little more than a square millimeter in area, the company makes devices like its PT120 that can sport 12 square millimeters of light emitting surface (that’s 4.6 x 2.6 millimeters). A larger LED means that fewer LEDs are needed to produce a lamp, which in turns leads to higher efficiencies.

“It ends up being more light per square millimeter,” said founder and CTO Alexei Erchak. “You can’t perfectly pack LEDs” into lamps.

The light that comes out of these larger LEDs is then chanelled by photonic lattices. The lattices—think of them as nano-sized pieces of optical communications equipment—effectively take the light that would radiate in all directions and force it out through the surface of the chip. Other reports have talked about the lattice, but generally neglected the size of the chip.  That large size sort of puts the pieces of the puzzle together. Laugh, but for some like me who’s spent a good part of his adult life studying chip size, this is pretty cool.

Several other researchers have tried to incorporate photonic lattices into products, but it hasn’t panned out. Luminus, says Erchak, is the first company to bring out a product that commercially exploits them.

“Photonic lattices were kind of overhyped in the late 90s,” he said. “People thought they could be used in telecom.”

Like Luxim, Luminus started out making light sources for projectors and projection TVs. Now that projection TVs are going away, Luminus is moving toward making lights for LCD TV makers (it has a deal with contract manufacturer Jabil Circuit) and for commercial and architectural lighting. LEDs still cost more than conventional lights, but they require less maintenance and consume less power. Thus, retailers, municipalities and large commercial building owners are already scoping out high-powered LEDs for garages and public gathering places. (Both companies, by the way, landed millions in VC money in recent months. Lighting is hot.)

The company’s PhlatLight CBM-360, which will begin to come out in sample quantities in the third quarter, will mark its entry into the market for white commercial lights. The produce will sport a 36 square millimeter emitting and be capable of putting out 4,000 lumens. (It can also be tuned to emit 80 lumens per watt if energy efficiency is more paramount than output.). Either way, that’s one honking bulb.