The exponential growth of data flying over the Internet is driving a shift from copper wires to optical fibers. At the chip level, 2.5D stacks of optical and electrical components look like the best way to marry the emerging electrical and optical worlds.
Those were the conclusions of a handful of speakers at a symposium on silicon photonics in Burlingame, Calif.
Copper will hit a wall at 25 Gbit/s, said Stephane Lessard, a senior researcher at Ericsson. Optical links increasingly will be needed to handle the annual 50 exabytes of Internet traffic forecast for 2015, up from an estimated 20 exabytes in 2013.
Integrating electrical and optical components side-by-side on top of an interposer will reduce board space, layer count, and materials cost, lowering board cost by a factor of nine compared to current solutions, Lessard said. In addition, signaling through fiber optic lines consumes much less power than using copper wires, he added.
Network operators will be able to reduce their power and cooling costs and extend the battery life of their systems during emergencies by moving to optical links, Lessard said. He noted a mandate for battery backing for routers, base stations, and other communications equipment to assure reliable network function even during power failures.
The savings are encouraging Ericsson to deploy photonics as fast as possible to serve the communication needs of the billion people currently using its gear. Lessard said he hopes the optical shift will be in full swing by 2016 -- which sounds very optimistic to me.
A handful of other speakers showed an ecosystem for the optical shift is slowly coming together. For example, Peter De Dobblelaere, vice president of engineering at Luxtera, said his company has already shipped half a million devices that integrate electrical and optical circuits on an interposer.
Michael Hochberg outlined a development environment for optoelectronic systems created by a lab he directs at the University of Delaware. Dim-Lee Kwong, an executive director from the Institute of Microelectronics in Singapore, shared IME's work with major corporations on interposers with the goal to eventually stack the heterogeneous die vertically. Richard Otte, chief executive of Promex Industries, provided chip- and board-level data on designing such stacks.
The speakers encouraged me to continue my personal mission of the last five-plus years of following the industry transition to 3D chip stacks. They confirmed the rapid growth of Internet data will require higher-bandwidth networks running at much lower power levels, driving the move to this technology.