NCSA NEWS

A new algorithm slices the computing time required to refine designs of surface-emitting lasers from 12 hours to 30 seconds.

Lasers are everywhere. These hair-thin beams of light guide weapons and surgical cuts, scan bar codes at check-out counters, and are responsible for the high fidelity of CD disks. They transmit data, video, and voices around the world at the speed of light.

Yet for all their versatility and power, existing lasers are as clunky and crude as the vacuum tubes that once powered radios. That's why researchers such as Karl Hess, a physicist and electrical engineer at the University of Illinois at Urbana-Champaign's Beckman Institute, are designing lasers so small that a million can fit on a child's fingernail. At that scale, lasers are the same dimension as microelectronic devices such as computer chips, opening the way for the greater integration of these two technologies -- optoelectronics -- in such high-demand applications as computers and telecommunications. The market for "vertical cavity surface-emitting laser" (VCSEL) products is expected to exceed a billion dollars by 2002, according to such industry experts as Jack Jewell, chief technical officer of Picolight, who built one of the first surface-emitting lasers in 1989 while at Bell Laboratories, and Michael Tan, a project manager for optoelectronics at Hewlett-Packard.

"Demand is being driven by the low cost of optical links," says Tan. "People want to use these lasers to construct backbones like the Internet that can handle gigabyte applications."

To optimize the design of these lasers, though, requires rigorous computing. Until recently, each refinement to a VCSEL design took at least 12 hours to recompute; in some cases it took as long as 600 hours. "That goes beyond what is fun, or what can be used for optimization," says Hess, who is a member of the Alliance's Nanomaterials Application Technologies Team. "An engineer can't tweak the simulation, wait 600 hours for the solution, then tweak it again. Before he had optimized a design, his boss would fire him."

Now Hess has a simulation method that may let engineers tweak a design to perfection without losing their jobs. He and graduate student Benjamin Klein, along with research scientist Leonard Register, have sliced the computing time for each optimization of VCSELs from 12 hours to about 30 seconds. Their work, which was the two-year-long thesis project of Klein, adapted a technique originally used for modeling radio antennas into a novel way of computing the behavior of the electromagnetic fields inside lasers. The technique enabled them to mathematically restructure the problem so that the bulk of their computations are processed, in parallel, on a supercomputer.