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Surface-emitting laser boasts 40Gbit/s data delivery

Posted: 08 Mar 2011 ?? ?Print Version ?Bookmark and Share

Keywords:surface-emitting laser? high-speed laser? data delivery?

A cheaper and more energy-efficient type of laser for fiber optics can deliver error-free data at a record rate of 40Gbit/s, according to researchers at Chalmers University of Technology. Known as surface-emitting laser, the innovation could pave the way for speedier and more reliable Internet traffic, computers and cellphones.

Today's commercial lasers can send up to 10Gb of data per second through optical fibers. This applies to both conventional lasers and to surface-emitting lasers. The Chalmers researchers have managed to increase the speed of the surface-emitting laser four times, and see the potential for further capacity increase.

"The market for this technology is gigantic. In the huge data centers that handle the Internet there are today over 100 million surface-emitting lasers. That figure is expected to increase a hundredfold," says Anders Larsson, professor in optoelectronics at Chalmers, who developed the high-speed laser together with his optoelectronics research group.

Unlike a conventional laser, the light from a surface-emitting laser is emitted from the surface of the laser chip (not from the edge), like in an LED. The gain is the ability to not only fabricate but also test the lasers on the wafer (a 75mm-wide substrate of semiconductor material of industrial type) before it is cut into individual chips for assembly. The lasers work directly where they sit on the wafer.

"Each wafer contains Up to 100 000 lasers chips. The surface emitting lasers can both be fabricated and tested before we cut the wafer into chips," says Larsson of Chalmers University of Technology.

Conventional lasers work only after partition. The ability to test up to 100,000 lasers on a wafer reduces the cost of production to one-tenth compared with conventional lasers. The laser volume is smaller. It requires less power without losing speed. The energy and power consumption is a tenth of what a conventional laser requires at 40Gbit/sonly a few hundred fJ/bit.

If Larsson and his co-workers succeed in their development, he expects that the power consumption of a complete optical link, between for example circuits in a computer (including drive electronics and receiver), will be no more than 100fJ/bit.

The next step for the Chalmers researchers is to modify the design and refine ways to control the laser, to increase speed and reduce power consumption even further.

"Each wafer contains up to 100,000 laser chips. The surface-emitting lasers can both be fabricated and tested before we cut the wafer into chips," Larsson explained.

"We strive to meet market demand ten years from now," Larsson said, estimating that by 2020, the industry will need energy-efficient cables that can handle 100Gbit/s per channel.

The research is being conducted at the Chalmers research center FORCE and is funded by the Swedish Foundation for Strategic Research, SSF and the EU through the project VISIT. Participating companies in the European project are IQE Europe (UK), VI Systems (Germany) and Intel (Ireland). Informal project partners are Tyco Electronics and Ericsson (Sweden). The findings are published in Electronics Letters from IEEE Explore.

- Julien Happich
??EE Times

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