An omnidirectional retroreflector based on the transmutation of dielectric singularities

Abstract

Transformation optics is a concept used in some metamaterials to guide light on a predetermined path. In this approach, the materials implement coordinate transformations on electromagnetic waves to create the illusion that the waves are propagating through a virtual space. Transforming space by appropriately designed materials makes devices possible that have been deemed impossible. In particular, transformation optics has led to the demonstration of invisibility cloaking for microwaves, surface plasmons and infrared light. Here, on the basis of transformation optics, we implement a microwave device that would normally require a dielectric singularity, an infinity in the refractive index. To fabricate such a device, we transmute a dielectric singularity in virtual space into a mere topological defect in a real metamaterial. In particular, we demonstrate an omnidirectional retroreflector, a device for faithfully reflecting images and for creating high visibility from all directions. Our method is robust, potentially broadband and could also be applied to visible light using similar techniques.

A transient thermal cloak experimentally realized through a rescaled diffusion equation with anisotropic thermal diffusivity

“…The manufacture efficiency of our device was mathematically improved by adopting a rescaled thermal equation and fully taking advantage of the abundance of natural materials with a wide range of thermal conductivity available from nearly zero to a value of 41000, which is impossible in the fabrication of EM devices. 3,9 Our work unambiguously proves the feasibility of extending EM TO devices into the thermal area and the robustness of the multilayer technique in fabricating complicated thermal devices, which may pave a new path to manipulate the dynamic heat flux for novel technological applications.…”

“…[1][2][3][4][5][6][7][8] The TO technique has also led to the creation of many other important EM devices with functionalities previously deemed impossible or unconceivable. [9][10][11] In general, this coordinate operation can be applied to different partial differential equations governing the behaviors of other physical phenomena such as thermal flux, [12][13][14][15][16][17][18][19][20][21][22][23] acoustic wave, [24][25][26][27] and matter or quantum [28][29][30] waves, demonstrating important scientific and application potentials.…”

Graded index photonic hole: Analytical and rigorous full wave solution

“…We note that based on the idea of "transmutation," an omnidirectional retroreflector, which originally requires material parameter with polynomial type of singularity, has been successfully fabricated in experiment. 18 The other way is to implement the design using a "reduced set of parameters," which means an approximate set of parameters in the field of transformation optics. This is the way by which the invisibility cloak was first realized.…”

“…12,13 The former offers a wide range of possibilities to locally tailor the electromagnetic ͑EM͒ response [14][15][16] while the latter allows the transmutation of dielectric singularities into a manageable topological defect. 17,18 One intriguing astroinspired optical device is motivated by the black hole, a fascinating celestial phenomenon. It is characterized essentially by a radially graded refractive index n͑r͒ϳ1 / r ␣/2 .…”

Super/Zero Scattering Characteristics of Circular SRR Arrays

“…The strong interest is motivated by the possibility to tailor the electromagnetic response that a periodic structure of metamaterials allows, which promises to have a significant impact in physics, optics and material science. Effective permittivities and permeabilities of metamaterials designed to range from negative to positive values have many important applications such as invisible cloaks [7][8][9][10], superlenses [11][12][13], microwave horn antennas [14] as well as other electromagnetic devices [15,16].…”