High negative refractive index in chiral metamaterials

Abstract

Conjugated bi-layer C8 metamaterials are proposed. Chirality and refractive index can be controlled effectively by the structure geometry. Extreme chirality results in a high negative refractive index for both right- and left-circular polarized excitations. The conjugated bi-layer C8 structures are fabricated and tested in microwave regimes. The measurement results are in good agreement with the simulation results. These proposed structures are additional promising candidates for high negative refractive index metamaterials which will facilitate different applications.

Dual-Band Terahertz Chiral Metamaterial With Giant Optical Activity and Negative Refractive Index Based on Cross-Wire Strucure

“…Generally, we can use the effective loss factor characterize how well the MMs behaves. The effective loss factor can be expressed as LF = |Im(n)/Re(n)| for average refractive index, and the loss factor of RCP and LCP can be expressed as LF = |Im(n ± )/Re(n ± )| [23,24]. The LF of the effective refractive index is less than 0.2 at resonances, which indicated that the loss of the proposed dual-band CMMs is relative small.…”

“…3(a), similar to the previous designed novel dual-band structure [20], the real part of chiral parameter Re(κ) .1) at these resonant frequencies, which indicate that the proposed MMs can achieve dualband negative refractive properties in THz region. The generations of the negative refractive indices are mainly due to the high chirality of the designed structure [3,24]. Generally, we can use the effective loss factor characterize how well the MMs behaves.…”

“…Various enantiomeric forms bi-layer planar chiral structure have been proposed and investigated widely, such as twist rosettes [7], twist cross wires [3,11,13], U shape SRRs [14], conjugate swastikas [15,16], and other novel bi-layer structures [17][18][19][20][21][22][23][24], which could exhibit negative refractive index and optical activity in a single frequency band or dual-band. More recently, negative refractive index of 3 dimensional compact helix structures also has been investigated in microwave frequency [25][26][27], however, which is hard to fabricate and integrate into present systems, especially in teraherz (THz) and optical region.…”

Flexible chiral metamaterials with dynamically optical activity and high negative refractive index

“…This ability is called as optical activity attracting many scientists for its potential application areas in scientific world, for example, analytical chemistry, molecular biology etc. Chiral media belong to a wider range of bi-isotropic media and it is characterized by [1][2][3][4] …”

Dynamic and tunable chiral metamaterials with wideband constant chirality over a certain frequency band

“…Chiral MTMs have received considerable attention in recent years for their ability to exhibit unusual electromagnetic (EM) properties such as strong optical activity [1], circular dichroism [2] and negative refraction [3], which are not seen in conventional materials. They are characterized by the quantity of chirality parameter, = ( − ) 2 ⁄ , where ⁄ is ratio representing the refractive indexes of the right circularly polarized (RCP) and left circularly polarized (LCP) waves and high chirality values lead to negative refractive index [4][5][6][7][8][9][10][11][12][13].…”