[Phate]

Startup Luxtera has announced its plans to enter the CMOS photonics market, anticipating the day when microprocessors will transmit information via light, not electrons.

The company claims that its optical modulator for transforming electrons into photons runs at 10-GHz, ten times the speed of an optical modulator Intel Corp. researchers began talking about last year. Beginning in mid-2006, Luxtera hopes to enter production of photonic devices using standard CMOS manufacturing processes.

Although the majority of chip-to-chip communications are conducted using copper-based interconnects, researchers are already looking toward the day when the balance shifts toward optical transmissions, initially for chip-to-chip interfaces between microprocessors, or between a microprocessor and memory device. Fibre optics are a standard component of modern telecommunication infrastructures, and interfaces such as Fibre Channel also use optical fibre interconnects to link up devices.

Although light slows down by some degree when transmitted through an optical medium, shifting to optical-based components is still too expensive than relying solely on copper, even when factoring in the additional power, heat, and crosstalk issues.

"The problem here that we can solve is a matter of bandwidth," said Gabriele Sartori, Luxtera's vice president of marketing and a former advocate for the HyperTransport protocol developed by Advanced Micro Devices.

Part of the relatively high cost of photonics comes from the fact that converting electrons to photons requires an intermediary device, such as the modulator Luxtera is designing. Today, that device exists as a separate module. Intel, Luxtera, and others are trying to integrate the optical waveguides within standard CMOS processes, that can be controlled by the standard voltage swings of a microprocessor.

However, doing so requires that the optical vendor have close ties to a microprocessor manufacturer. At Intel, that's no problem. Luxtera, on the other hand, has worked closely with Freescale Semiconductor to develop the technology. Finding a partner like Freescale is "necessary," Sartori said. "You must walk before you can run."

Freescale has taped out several engineering samples of the optical technology, including a chip, one side of which includes the optical interface built in. The sample chip use a 130-nm SOI process, the same technology used to fabricate the G4 microprocessor. Part of Luxtera's job has been to develop silicon libraries, the files used to design the photonic chips in the same way other libraries serve as the blueprint for making more conventional semiconductors.

The 32-employee startup originally received $7 million funding from Sevin Rosen Funds and August Capital in 2001, followed by an additional $15 million by New Enterprise Associates in 2003. Eli Yablonovitch, a professor at UCLA who developed photoelectronic crystals, sits on the company's board, while Arno Penzias, who won the 1978 Nobel Prize for his work on the Big Bang theory, serves in an advisory role. Other board members include Andy Rappaport of August Capital, which funded Transmeta, among others.