TI (Dallas) on Monday (April 23) will introduce a reference design, called the Optical Wireless Solution, that marks the debut of the company's application of its 3-D microelectromechanical system (MEMS) mirrors to networking systems. The design allows Ethernet to be beamed via infrared to individual users within a 50-meter line-of-sight radius.

The micromirrors concentrate a signal at a particular point, allowing the OEM to send data rates of up to 100 Mbits/second on the infrared links, said Jose Melendez, worldwide manager of analog MEMS networking products for TI. By contrast, standard IR ports hit their target by spreading the light across a wide area, lowering the bandwidth that can be sent over a particular beam.

Vbrick Systems Inc. (Wallingford, Conn.) is scheduled to demonstrate TI's technology in Las Vegas this week at the National Association of Broadcasters conference.

TI is targeting small office networks, but others see possibilities for even smaller cross-connects in areas like protection switching, where even a humble, 1 x 2-port device can be useful. Startups such as Optical Switch Corp. (Richardson, Texas) are exclusively targeting the market for small all-optical switches.

At the other end of the spectrum, such companies as Calient Networks Inc. (San Jose, Calif.) and Xros Inc. (now part of Nortel Networks) are pressing toward what they believe is the inevitable implementation of 1,000 x 1,000-port switches. But several players in all-optical networking don't believe the core switch market is a realistic target.

"Many of our partners and customers are working on those kinds of systems, but they really aren't all developed yet," said Jeremy Chappell, vice president of business development for Optical Switch.

Even when deployed, the switches won't represent a very large market, said Robert Potenza, senior vice president of sales at Blue Sky Research Inc. (San Jose, Calif.), another startup developing all-optical cross-connects.

Bigger switches, smaller market

"For the big switches, they're talking about volumes of a few hundred at most," Potenza said. "Yeah, they're zillions of dollars, but only a few people will make them."

Even Calient and Optical Micro Machines Inc. (San Diego), which have both announced plans for 1,000 x 1,000 switches, got their start selling much smaller devices.

Extremely small all-optical switches imply less risk for the equipment builders that would buy them. The 1 x 2 devices are useful in protection switching, for example, wherein a light signal can be rerouted to a spare fiber-optic cable if the primary line fails. Likewise, 2 x 2 parts "seem to be useful as a bypass, taking a line in or out," Potenza said.

Optical Switch is among the recently announced players tackling the lower port counts. At the Optical Fiber Conference (OFC), the startup showed switches no larger than 1 x 128 or 16 x 16.

The company makes modules and subsystems based on one of two switching methods. Its FiberKey family of extremely small devices deflects light inside a crystal, taking advantage of a principle called frustrated total internal reflection. The property allows light to be channeled with a loss so small as to be "almost invisible to the network," Chappell said.

The FiberKey parts, in configurations of 4 x 8 and smaller, are being marketed as components not for all-optical switches but for traditional, electronic switches. "The service providers will gradually introduce all- optical into the networks," Chappell said. "The next immediate move will be in areas like protection switching."

The FiberKey offerings are completing beta test now, and volume production is imminent, Chappell said.

Optical Switch's larger switches use an entirely different technology, called free-space conformal optics, which is similar to MEMS mirrors. At OFC, the company demonstrated switches in this family, called Kaleidoscope, in sizes up to 1 x 128 ports.

Kaleidoscope is a compromise between the 2-D and 3-D MEMS alternatives. A single swiveling mirror is used inside each part to create a 1 x n connection. The most obvious application for Kaleidoscope is in network monitoring, where a 1 x 32 part, for example, could be used to monitor 32 lines for power strength, Chappell said.

Kaleidoscope parts also can be cascaded to form large cross-connects. Optical Switch demonstrated a two-stage 16 x 16 subsystem, using 32 mirrors, at OFC.

But company officials have announced no intentions to chase the 1,000-port-switch market, saying they're content with serving the protection and monitoring market.

"It's very useful to be able to deploy very good small-port-count switches," Chappell said.

TI's reference design, in addition to the micromirrors, uses two of the company's C54X digital signal processors with integrated 10/100-Mbit/s Ethernet media-access controllers. The micromirrors themselves are 10 mm² devices capable of tilting on two axes, giving them a range of possible reflection targets.

While most MEMS devices use electrostatic forces to move the mirrors, TI's are electromagnetic devices, meaning they push the mirror with repelling magnetic fields. The method requires roughly 5 volts, as opposed to the 100 V or more required for electrostatics, Melendez said.

Startup Blue Sky is among the other companies developing electromagnetic MEMS mirrors.

Micromirror per user

TI is suggesting the use of one micromirror per user, creating an Ethernet switch with a dedicated connection to each user. The number of users will vary, but "between 12 and 24 users" is a typical number, Melendez said.

The technology could be extended to arbitrary bandwidth rates, but TI chose 100 Mbits/s because it's a common level of high-speed LAN performance, Melendez said.

TI isn't revealing any other plans for its micromirrors, citing the Optical Wireless design as the only one that OEMs are preparing to ship. Melendez did say TI is talking with customers in the free-space optics market, a similar business that uses rooftop transmitters to beam information between buildings. A reference design along those lines is possible, he said.

Melendez would not say whether TI eventually plans to enter its micromirrors into the core switching market. While that market has sparked interest among OEMs, he said, "today there's not an established market where companies are shipping large arrays of analog micromirrors."