Metamaterials, by definition, are man-made. And traditionally, they also are expensive to produce and sometimes difficult to manufacture using traditional semiconductor processes.

Researchers at Purdue University’s College of Engineering in Indiana set out to change that equation, creating a “hyperbolic” metamaterial for optics without the need to add gold or silver. They settled on aluminum-doped zinc oxide, aka AZO.

By creating a structure with 16 layers, alternating AZO and regular zinc oxide, they were able to create optical metamaterials that can actually change the behavior of light. According to the university, light passing from the zinc oxide to the AZO hits an “extreme anisotropy,” which causes the light to disperse hyperbolically.

That effect can be altered further by either varying the levels of aluminum or adding an electrical field. By increasing or decreasing the voltage, the material can be hyperbolic or non-hyperbolic, and act like metal or a dielectric material. That fits in perfectly with quantum computing, which alternates between ones and zeroes depending upon the state, voltage or current applied.

What makes this particularly interesting is that it allows light to be controlled at less than its wavelength. The university says that metamaterials can sharply reduce the refraction index. AZO, in addition, is plasmonic, because it conducts clouds of electrons.

The work is being funded by the U.S. Office of Naval Research, the National Science Foundation, the Air Force Office of Scientific Research, as well as Purdue.

—Ed Sperling

Tags: Purdue University

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