Researchers Design More Reliable Invisibility Cloak

The design of the invisibility cloak consists of a spoke-like configuration of glass resonators, which form a magnetic resonance that is used to obtain the desired parameters of the medium. The illustration shows the glass cloak designed to hide a metal cylinder of 15 micrometers in diameter. Image credit: Semouchkina, et al.

In the study, Elena Semouchkina from Michigan Technological University and Pennsylvania State University and her coauthors designed an invisibility cloak made of glass for the infrared range. Currently, most metamaterial cloak designs require that the metamaterial response be homogeneous. However, the new design relies on simulations of a true multi-element cloak structure and takes into account the inhomogeneity of a real metamaterial response.

“This is one of the first designs of an optical cloak, in particular, of a cylindrical shell,” Semouchkina told “This is a non-metallic low-loss all-dielectric cloak. … In contrast to the previous designs, the design of our cloak has been developed at a careful control of interactions between resonators, since a true multi-resonator structure has been simulated. It makes the design essentially more reliable.”

The structure of the proposed cloak consists of identical nanosized chalcogenide glass resonators arranged in a concentric pattern. In simulations, the researchers found that glass resonators in the shape of a cylinder with a diameter of 300 nm and a height of 150 nm provided the best results for the light wavelength of 1 micron.

“The design employs identical resonators in all layers of the cloak, which, from the point of view of fabrication tolerance, presents a tremendous advantage versus fabricating nano-sized elements of different prescribed dimensions,” Semouchkina said.

The spoke-like configuration of the resonators forms radial magnetic moments despite different incidence angles of incoming light. As Semouchkina explained, the magnetic resonance response creates the desired effective parameters of the medium. [Read more at]