They describe developing a nonmetallic cloak that uses identical glass resonators made of chalcogenide glass, a type of dielectric material (one that does not conduct electricity). In computer simulations, the cloak made objects hit by infrared waves—approximately one micron or one-millionth of a meter long—disappear from view.
Earlier attempts by other researchers used metal rings and wires. “Ours is the first to do the cloaking of cylindrical objects with glass,” Semouchkina said.
Her invisibility cloak uses metamaterials, which are artificial materials having properties that do not exist in nature, made of tiny glass resonators arranged in a concentric pattern in the shape of a cylinder. The “spokes” of the concentric configuration produce the magnetic resonance required to bend light waves around an object, making it invisible.
Metamaterials, which use small resonators instead of atoms or molecules of natural materials, straddle the boundary between materials science and electrical engineering. They were named one of the top three physics discoveries of the decade by the American Physical Society. A new researcher specializing in metamaterials is joining Michigan Tech’s faculty this fall.
Semouchkina and her team now are testing an invisibility cloak re-scaled to work at microwave frequencies and made of ceramic resonators. They’re using Michigan Tech’s anechoic chamber, a cave-like compartment in an Electrical Energy Resources Center lab, lined with highly absorbent charcoal-gray foam cones. There, antennas transmit and receive microwaves, which are much longer than infrared light, up to several centimeters long. They have cloaked metal cylinders two to three inches in diameter and three to four inches high.
“Starting from these experiments, we want to move to higher frequencies and smaller wavelengths,” the researcher said. “The most exciting applications will be at the frequencies of visible light.”