Circular polarization converters based on bi-layered asymmetrical split ring metamaterials

Wu, Lin; Yang, Zhenyu; Cheng, Yongzhi; Gong, Rongzhou; Zhao, Ming; Zheng, Yu; Duan, Ji’an; Yuan, Xiuhua

doi:10.1007/s00339-014-8252-3

Cited by 72 publications

(36 citation statements)

References 25 publications

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“…[5][6][7][8][9] Several high-efficiency wave retarders have been demonstrated through different metamaterial microstructure designs, and these polarization wave retarders were demonstrated for conversion between different polarization states, such as linear to linear, [10][11][12][13][14] linear to circular, 15,16 and circular to circular polarization. 17 Compared with the traditional wave plates, these metamaterial-based wave retarders have advantages including subwavelength thickness, high conversion efficiency, angular tolerance, and scalability. In most of the existing wave retarders, the polarization states are manipulated in the transmission mode with a limited number of designs operating in the reflection mode.…”

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confidence: 99%

Ultrabroadband reflective polarization convertor for terahertz waves

et al. 2014

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We design and experimentally demonstrate an ultrathin, ultrabroadband, and highly efficient reflective linear polarization convertor or half-wave retarder operating at terahertz frequencies. The metamaterial-inspired convertor is composed of metallic disks and split-ring resonators placed over a ground plane. The structure exhibits three neighboring resonances, by which the linear polarization of incident waves can be converted to its orthogonal counterpart upon reflection. For an optimal design, a measured polarization conversion ratio for normal incidence is greater than 80% in the range of 0.65-1.45 THz, equivalent to 76% relative bandwidth. The mechanism for polarization conversion is explained via decomposed electric field components that couple with different resonance modes of the structure. The proposed metamaterial design for enhancing efficiency of polarization conversion has potential applications in the area of terahertz spectroscopy, imaging, and communications. V C 2014 AIP Publishing LLC. [http://dx.Terahertz science and technology have seen rapid development, underpinned by many promising applications in imaging, sensing, and communications. 1 Towards these applications, high-performance terahertz components become essential for manipulating terahertz waves. One important group of components is related to polarization manipulation, including polarizers, wave retarders, and polarization rotators. In particular, conventional wave retarders can be achieved by using waveplates made of natural birefringent materials with a retardation effect. 2,3 Those wave plates require a relatively long propagation distance to obtain sufficient phase accumulation, despite the limited operation bandwidth and availability. Thus, more convenient and flexible approaches are desirable to fully manipulate the polarization state of electromagnetic waves.Over the past decade, metamaterials as artificial composite materials have attracted great attention due to their exotic electromagnetic properties unavailable to natural materials. 4 Such unique properties open up significant opportunities, including an alternative approach to manipulating the polarization of electromagnetic waves. 5-9 Several high-efficiency wave retarders have been demonstrated through different metamaterial microstructure designs, and these polarization wave retarders were demonstrated for conversion between different polarization states, such as linear to linear, 10-14 linear to circular, 15,16 and circular to circular polarization. 17 Compared with the traditional wave plates, these metamaterial-based wave retarders have advantages including subwavelength thickness, high conversion efficiency, angular tolerance, and scalability. In most of the existing wave retarders, the polarization states are manipulated in the transmission mode with a limited number of designs operating in the reflection mode. 11,12,15,18 For most retarders in the reflection mode, the undesirable high co-polarization reflection severely limits the polarization conversion efficienc...

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confidence: 99%

Ultrabroadband reflective polarization convertor for terahertz waves

et al. 2014

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“…To go a step further, we will demonstrate our proposed CMMs numerically and experimentally for the multi-band circular polarization conversion. Since the split-ring resonators (SRRs) allow for a control and manipulation of EM (light) waves on sub-wavelength length scales [8,12,14,15,23], which is also employed as the basic element in our design. Figs.…”

Section: Fundamental Theory and Unit-cell Structure Designmentioning

confidence: 99%

“…From microwave to optical ranges, negative refraction [1], giant gyrotropy [2], optical activity [3][4][5][6], circular dichroism (CD) [7][8][9], asymmetric transmission (AT) [10][11][12][13], and linear or/to circular polarization conversion [14][15][16] can be explored and realized by special CMM design. Essentially, these unique EM properties mainly originate from cross-coupling of the electric and magnetic fields among these chiral structures [17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Ultra-Compact Multi-Band Chiral Metamaterial Circular Polarizer Based on Triple Twisted Split-Ring Resonator

Cheng¹,

Cheng³

et al. 2016

PIER

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Abstract-An ultra-compact chiral metamaterial (CMM) using triple-layer twisted split-ring resonators (TSRRs) structure was proposed, which can function as a multi-band circular polarizer. This ultra-compact structure CMM can convert an incident linearly y-polarized (x-polarized) wave propagating along the −z(+z) direction to the transmitted left circularly polarized (LCP) waves at 7.28 GHz, 13.22 GHz and 15.49 GHz while the right circularly polarized (RCP) waves are at 9.48 GHz simultaneously. In addition, the large polarization extinction ratio (PER) of more than 20 dB across four resonance frequencies can be achieved. The experiment results are in good agreement with the numerical simulation results. The surface current distributions of the structure are analyzed to illustrate this linear to circular polarization conversion. The unit cell structure is extremely small both in longitudinal and transverse directions. Good performances and compact design of this CMM suggest promising applications in circular polarizers that need to be integrated with other compact devices.

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“…Metallic chiral metamaterials based on stacked 2D designs have been shown to possess strong circular dichroism from more narrow operation bandwidths. [34][35][36][37] Existing experimental broadband designs for near-infrared frequencies exhibit circular polarization conversions over large bandwidths of up to one octave. [ 38,39 ] However, for these designs polarization conversions are below 50% throughout most of the operation band, even in the corresponding numerical calculations.…”

Section: Introductionmentioning

confidence: 99%

A Helical Metamaterial for Broadband Circular Polarization Conversion

Kaschke

Blume

et al. 2015

Advanced Optical Materials

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visible-to microwave-frequencies, [3][4][5][6] however, with rather small operation bandwidths. Likewise, 3D chiral dielectric photonic crystals [7][8][9][10][11] also show fairly small operation bandwidths.In sharp contrast, metallic helical metamaterials exhibit circular dichroism over an unmatched bandwidth of well above one octave. Starting with square arrays of single gold helices that function as broadband circular polarizers with high extinction ratio in the mid infrared, [ 12,13 ] recently research has led to more complex unit cells. For example, by tapering the helix radius along the helix axis, the extinction ratio and the bandwidth can be enhanced simultaneously. [ 14 ] Double-helical unit cells have also been proposed to lead to higher extinction ratios and enlarged bandwidths. [15][16][17][18] Circular polarization conversions are often unwanted for polarizer applications. They can be eliminated by recovering either threefold or fourfold rotational symmetry by intertwining three or four helices, respectively, within one unit cell of a lattice with the same rotational symmetry. [19][20][21][22][23] Applications beyond circular polarizers such as broadband absorbers [ 24 ] or chiral near-fi eld sources [ 25 ] have also been proposed.While for circular polarizers a large difference of the diagonal elements of the Jones transmission matrix is desired, chiral metamaterials can also be designed to exhibit strong circular polarization conversions corresponding to the off-diagonal elements. Even though converting one circular polarization to the other can be achieved by half-wave plates at visible frequencies, these wave plates are often limited in bandwidth and not readily available at many other frequency ranges.Furthermore, a large difference in these off-diagonal elements can be of interest, both in linear and circular polarization basis. This effect is often referred to as "asymmetric transmission" due to the symmetry of the Jones transmission matrix. Applications like diode-like devices exploiting asymmetric Jones matrices have been proposed. [ 26 ] Metamaterial designs with highly asymmetric polarization conversions have been realized for linearly polarized light, both at infrared-and terahertz-frequencies. [ 27,28 ] More recently, many more designs for linearly polarized light have been proposed with both high extinction ratios and large bandwidths. [29][30][31][32][33] Asymmetric polarization conversions for circular polarization, on the other hand, has only been reported recently, however, with generally much Metallic helical metamaterials give rise to broadband and scalable chirooptical effects orders of magnitude higher than found in nature. While arrays of gold helices have been suggested as compact circular polarizers, where a large difference of the diagonal elements of the Jones transmission matrix is desired, chiral metamaterials can also be designed to exhibit strong circularpolarization conversions. Here, a novel helical metamaterial design, exhibiting asymmetric, broadband circular-polari...

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Circular polarization converters based on bi-layered asymmetrical split ring metamaterials

Cited by 72 publications

References 25 publications

Ultrabroadband reflective polarization convertor for terahertz waves

Ultrabroadband reflective polarization convertor for terahertz waves

Ultra-Compact Multi-Band Chiral Metamaterial Circular Polarizer Based on Triple Twisted Split-Ring Resonator

A Helical Metamaterial for Broadband Circular Polarization Conversion

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