By Ben Coxworth
Last Thursday at the Optical Fiber Communication Conference in Los Angeles, a team from IBM presented research on their wonderfully-named “Holey Optochip.” The prototype chipset is the first parallel optical transceiver that is able to transfer one trillion bits (or one terabit) of information per second. To put that in perspective, IBM states that 500 high-def movies could be downloaded in one second at that speed, while the entire U.S. Library of Congress web archive could be downloaded in an hour. Stated another way, the Optochip is eight times faster than any other parallel optical components currently available, with a speed that’s equivalent to the bandwidth consumed by 100,000 users, if they were using regular 10 Mb/s high-speed internet.
One of the unique features of parallel optic chips is the fact that they can simultaneously send and receive data. The Holey Optochip capitalizes on that feature, for its record-setting performance.
The “Holey” in the name comes from the fact that the team started with a standard silicon CMOS chip, but bored 48 holes into it. These allow optical access to its inside back surface, where 24 separate receiver and transmitter channels are located – for a total of 48 channels. Each of those channels has its own dedicated VCSEL (vertical cavity surface emitting laser) and photodetector, which are used respectively for sending and receiving data. The chip is designed to be coupled to a multimode fiber array, via a microlens optical system.
The back of the IBM Holey Optochip, with lasers and photodectors visible through substrate holes
All parts of the Optochip are made from commercially-available components, which should keep costs down on a production model. Also, the chip consumes less than five watts when operating – 20 of the devices could run on the power consumed by one 100-watt light bulb.
“We have been actively pursuing higher levels of integration, power efficiency and performance for all the optical components through packaging and circuit innovations,” said IBM Researcher Clint Schow. “We aim to improve on the technology for commercialization in the next decade with the collaboration of manufacturing partners.”