February 20, 2009--An Executive Panel on "Silicon Photonics and Optical Interconnects" at SPIE Photonics West 2009 offered attendees an opportunity to learn from and interact with leading silicon-photonics scientists and management regarding the roadmap for this technology. Held on Tuesday, January 27, the executive panel brought together five prominent technologists who agreed that photons trump electrons when it comes to designing tomorrow's high-speed computers.
Panel executives were Mario Paniccia, Photonics Technology Laboratory director at Intel (Santa Clara, CA); Ashok Krishnamoorthy, distinguished engineer at Sun Microsystems Physical Sciences Center (San Diego, CA); Ray Beausoleil, principal scientist at Hewlett-Packard Laboratories (Palo Alto, CA); Eugene Fitzgerald, professor of Materials Engineering at the Massachusetts Institute of Technology (Cambridge, MA); and Jeffrey A. Kash, research staff member at the IBM Thomas J. Watson Research Center (Yorktown Heights, NY). The following video introduces each panel member and briefly explains their views on silicon photonics:
Paniccia said that even today's four- and sixteen-core processors weren't enough to meet the demands of Moore's Law, and that the real problem was not individual processor capabilities, but the problem of moving data in and out of the central processing unit (CPU). Electrical connections simply cannot achieve the processing speeds required by today's demanding video and image-processing applications; however, Paniccia cautioned that optical solutions need to be carefully considered in terms of cost and manufacturability. His sentiments were supported by Beausoleil, who said, "The physical limitation of wires is real." Beausoleil believes, like the other panel members, that computer companies will hit a brick wall in a few years, despite the ongoing efforts to shrink feature sizes below 45 nm through continuing lithography innovations.
While all the panel members agreed that electrical connections between chips need to be replaced by optical connections, different arguments were presented for how to build the various components needed for an all-optical scenario. Fitzgerald favors the indium phosphide (InP) integrated circuits that are compatible with complementary metal-oxide semiconductor (CMOS) processing.
The light source
But when it came to the question "Is there agreement on where the light comes from?" posed by moderator Peter Hallett, manager industry relations, exhibitions, and sales at SPIE (Bellingham, WA), there was surprising agreement that the short-term (five-year) source solution would not be a purely silicon device. Paniccia said that we all agree there won't be a silicon laser anytime soon. He added that efficiencies and milliwatts power levels, along with the inability to electrically pump a device, were hurdles to any introduction of a truly silicon laser.
Fitzgerald and Krishnamoorthy favored a III-V on silicon, CMOS-compatible light source that could take computing companies beyond the "academic" desire for a purely silicon laser, and assist in the optical-computing revolution. Beausoleil agreed, saying that 64 flip-chipped distributed feedback lasers simply wouldn't work as an on-chip solution. Krishnamoorthy went a step further and said that he'd rather see the source off the chip, outside the data equipment rack, to avoid having to deal with source cooling or powering difficulties.
A more in-depth summary of the panel discussion appears in the February 15 issue of Optoelectronics Report at www.laserfocusworld.com/articles/353528.
--Posted by Gail Overton, gailo@pennwell.com; www.laserfocusworld.com.
