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NCSA NEWS |
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 Mirror sections consisting of alternating layers of gallium
arsenide (light gray) and aluminum gallium arsenide (white).
 Gain region where light is amplified.
TOP LEFT: Vertical cavity surface-emitting lasers (VCSELs) operate on the same principles as conventional laser diodes but are one hundred times smaller (about 1 micrometer) and have been turned on end so that light shoots out the top. Their vertical orientation and minuscule size enable industry to pack more of them onto a wafer.
TOP CENTER: Researchers typically simulate VCSELs by placing a computational grid,
or mesh, over their model and attaching to each grid point linear equations
that express the laser's optical and electronic behavior at that point. The
researchers then solve these millions of equations in order to describe how
the entire laser behaves. This is painfully slow because the equations are
solved simultaneously.
TOP RIGHT: Hess and Klein's method is faster because they mesh a smaller area -- only
the gain region -- so there are fewer grid points to solve for, and they
shift the bulk of the computing to the step in the problem that can be
computed in parallel on a supercomputer. The key is their use of a Green's
function in defining the grid points. This mathematical expression takes
into account the laser's behavior at each grid point as well as in relation
to the rest of the laser so the researchers obtain as much detail as if
they had meshed the entire model.
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