Rotatable illusion media for manipulating terahertz electromagnetic waves

Abstract

Based on composite optical transformation, we propose a rotatable illusion media with positive permittivity and permeability to manipulate terahertz waves, and a new way to realize singular parameter-independent cloaks when the incident wave with a certain width propagates from specific incident directions. The fundamental mechanism of this kind of cloak is that the illusion media can be able to avoid the incident wave interacting with the objects. Comparing with traditional transformation-coordinate-based cloaks such as cylindrical-shaped cloaks, our cloaks are independent of singular material parameters. Furthermore, this type of rotatable illusion media can be applied to design tunable miniaturized high-directivity antenna (a small antenna array covered with the rotatable illusion media appears like a large one and meanwhile, the radiation directions of the small antenna array is tunable via this rotatable illusion media). Full wave simulations are performed to confirm these points.

Transformation Optics: From Classic Theory and Applications to its New Branches

“…A wave rotator is another typical classic device designed by TO that has been applied to beam‐angle steering and even cloaking effects . We can use the following spatial rotation transformation to achieve an optical rotator: where a and b are radii of the inner and outer boundary of the rotator.…”

“…have been designed and even experimentally demonstrated with TO, including an invisibility cloak, [20,[26][27][28][29][30][31][32] wave concentrators, [33,34] rotators, [35][36][37][38] beam splitters, [39,40] compressors, [41] perfect lenses, [42][43][44] illusion optical devices, [45,46] PEC reshapers, [47,48] superscatterers, [49][50][51][52] optical black holes, [53][54][55] optical wormholes, [56,57] wavefront modulators, [58,59] waveguide devices, [60][61][62] and antenna radiation controllers, [63][64][65] etc. Among these works, there are some notable experimental milestones, such as the realizations of an invisibility cloak in the microwave band, [27,28] infrared band [29] and visiblelight band, [32] electromagnetic wave rotators for microwave [36] and terahertz ...…”

“…A wave rotator is another typical classic device designed by TO that has been applied to beam-angle steering [35,36] and even cloaking effects. [37] We can use the following spatial rotation transformation to achieve an optical rotator:…”

“…geometrical optics, wave diffusion theory, Fourier optics, etc.) have been designed and even experimentally demonstrated with TO, including an invisibility cloak, wave concentrators, rotators, beam splitters, compressors, perfect lenses, illusion optical devices, PEC reshapers, superscatterers, optical black holes, optical wormholes, wavefront modulators, waveguide devices, and antenna radiation controllers, etc. Among these works, there are some notable experimental milestones, such as the realizations of an invisibility cloak in the microwave band, infrared band and visible‐light band, electromagnetic wave rotators for microwave and terahertz waves, and a microwave highly directive emitter …”

Far-field high resolution effects and manipulating of electromagnetic waves based on transformation optics

“…The main principle is based on the form invariance of Maxwell equations under coordinate transformation. By using a proper coordinate transformation, TO can be applied to design many fantastic devices, such as cloaks [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], field rotator [22,23], field concentrator [24], tunnel waves [25], antenna [26,27], retrodirective reflector [28], transparent wall [29], illusion systems [30][31][32][33], optical switch [34] and power combiner [35].…”