Nanowerk June 15, 2021
Perfect optical cloaking requires the total scattering of electromagnetic waves around an object at all angles, all polarizations, over a wide frequency range, irrespective of the medium. By simplifying the invisibility requirements, pioneering work on spherical transformation cloaks, carpet cloaks, plasmonic cloaks, and mantle cloaks has been realized in narrowband microwave, infrared, and even optical wavelengths. In a tutorial a team of researchers in the US (University of Michigan, industry) review the theoretical basis for invisibility cloaking, from spherical transformational optics to non-Euclidian cases, and discuss their limitations. Because the human eye is insensitive to the phase and polarization of visible light, a class of ray optics cloaking devices has been recently developed by eliminating phase preservation requirements. They highlight the recent trends in realizing reconfigurable intelligent cloaks to overcome the traditional limitations of wideband operation and parallel efforts in unidirectional cloaking focussing on the recent progress achieved on invisibility cloaks that function in natural incoherent light and can be realized using standard optical components. They conclude with potential applications and the practicality of optical cloaks in everyday life…read more. Open Access TECHNICAL ARTICLEÂ
Carpet cloak where the regions in cyan are transformed between the virtual and physical systems… Credit: Journal of Applied Physics 129, 231101 (2021)Â