Start-Up Claims Breakthrough in Optical Switching

Start-up Lynx Photonic Networks Inc. says it has an optical-to-optical switching technology that's needed by optical backbones and is more reliable than alternatives from other vendors.

Lynx is introducing an optical switch fabric that switches light from optical fiber to optical fiber without having to first convert the light into an electrical signal, an essential capability of high-speed optical networks.

Lynx claims the technology is more dependable than alternatives because it doesn't rely on moving parts, nor does its components go through state changes, such as turning from a liquid to a gas. Tiny adjustable mirrors used in Lucent's Lambda Router, for instance, have such moving parts. Optical switching fabric made by Agilent uses tiny bubbles created by heating a liquid into a gas to divert light.

Industry experts say mirrors and bubbles have not withstood the test of time, so it is uncertain whether a device based on them would require periodic maintenance to replace them.

The Lynx technology, called silica thermo-optic switching, directs light by altering how much a wavelength path is bent as it passes through gateways made of silica. These gateways are narrow channels called waveguides that run through silica wafers. Optical fibers are attached to the waveguides at the edge of the wafers.

The gateways block light from incoming fibers or allow it through, thereby determining which exit fiber the light leaves by.

These gateways can be opened or closed in a millisecond by warming them with microvoltage heaters. The heat changes the refractive index of the silica, essentially blocking the light from following that path through the switch.

The switch is capable of broadcasting or multicasting wavelengths and does so with less loss of signal as it is switched than other methods, Lynx claims. By keeping the signal stronger, the switch will enable networks that require fewer optical-to-electrical-to-optical regenerators, which drive up the cost of building and maintaining a network.

Lynx makes not only the switch, but also the software to control the heaters.

Other manufacturers would buy Lynx's product and build it into optical cross-connects, protection switches, optical add-drop multiplexers and optical demultiplexers.

The company has a switch that can handle an eight-by-eight grid of waveguides. It says it will have a 32-by-32 switch by the third quarter of 2001.www.LynxPN.com