Pushing the boundaries of optical communications

Mitel Corporation has produced working prototypes of photonic devices aimed at improving the price/performance ratio of Dense Wave Division Multiplexing.

Mitel Corporation has produced working prototypes of photonic devices aimed at improving the price/performance ratio of Dense Wave Division Multiplexing (DWDM) by an order of magnitude or more.

DWDM is a key enabling technology to meet the insatiable demand for bandwidth on the backbone of the Internet. The technology allows more information to be carried over a single fibre by multiplexing (or mixing) multiple wavelengths of light.

Mitel’s breakthrough allows a higher number of wavelengths (or channels) of information to be multiplexed at lower cost. Currently most commercially available products handle 16 channels. Newer offerings can go to 40 channels using a technique called Arrayed Waveguide Grating (AWG) but are limited in capacity by the large dimensions of the chip and by performance constraints imposed by conventional production techniques. Sometimes, such devices are also expensive to manufacture as they employ complex materials and specialty processes.

To overcome these limitations, Mitel employed a different form of grating known as an Echelle Grating and tapped into its semiconductor fabrication expertise to develop a number of proprietary, patentable techniques and built a better chip. The result may lead to a higher-capacity, single-chip device based on standard semiconductor materials that dramatically alters the economics of high-speed optical communications.

‘Moving this technology to silicon instead of relying on more expensive and exotic materials, holds significant promise for cheaper, more reliable devices that are essential for high-speed optical transmission,’ said Dr. R. Normandin, director general, Institute for Microstructural Sciences, National Research Council of Canada.

‘This is an example of what some people call disruptive technology,’ said Moris Simson, senior vice president and chief technology and marketing officer, Mitel Corporation. ‘By being able to etch deep enough, smooth enough and vertical enough into silica, we have laid the foundation for dramatic improvements in the capacity, size and cost of these devices.’

‘With a 40 channel multiplexing device, we believe our footprint per channel is five times smaller than competing alternatives, ‘ said Dr. John Miller, Director of Photonics, Mitel Semiconductor. With this level of miniaturisation, our approach provides unprecedented scalability leading to higher capacities and reduces the need for expensive, highly specialised amplifiers in the network. Mitel’s current prototype conforms to the ITU-T grid with 100 GHz channel spacing. An 80-channel 50 GHz device is also in development.’

The optical multiplexer family of products resulting from this research will be called LightRider and will be targeted to DWDM equipment serving metropolitan area networks. This market is currently estimated at US $375 million and forecasted to reach US $2.04 billion by 2004. Mitel expects to provide its lead customers with LightRider samples for evaluation by early next year.

More information on Mitel is available at www.mitel.com