Multiple such manipulations can be combined or performed in sequence, allowing metamaterial researchers to change the shape of waves in complex ways.
To begin, the researchers created a computer simulation of an ideal metamaterial, one that could perfectly change the shape of the incoming wave profile into that of its derivative. With the ideal metamaterial as a guide, the researchers then constrained their simulations to specific materials suitable for existing fabrication techniques, such as silicon and aluminum-doped zinc oxide.
"The simulation results of the two were almost identical, so we're hopeful we'll be able to do photonic calculus in a physical experiment in the future," Engheta said.
Once built, these metamaterials could be put to use doing specific computational tasks that are best suited to an analog approach. Taking derivative of an algebraic function, for example, is a task that digital computers must perform by brute force, essentially scanning the curve and evaluating the difference between every pair of neighboring points. Even though modern digital computers can scan the 2-D profile very quickly, the time to complete the task increases along with the size of the profile. A computational metamaterial designed to calculate derivatives with light waves, by contrast, could complete the task nearly instantaneously regardless of the size of the profile, as it would operate on all points at once.
One analog-suited application that might make direct use of such computational metamaterials is edge detection, an increasingly common image processing technique that helps software find faces and identify objects in pictures.
|Contact: Evan Lerner|
University of Pennsylvania