Broadband transparent metamaterial linear polarization transformer based on triple-split-ring resonators

Abstract

In this paper, a chiral metamaterial (CMM) with triple-layer twisted split-ring resonators structure was proposed, which could exhibit a linear polarization conversion as well as asymmetric transmission only for forward and backward propagating linearly polarized waves in a broadband frequency range. The polarization of broadband linearly polarized electromagnetic waves can be rotated in a specific direction by passing it through such a CMM slab with a thickness of about one-twelfth the operational center wavelength. Experiment and simulation calculations are in good agreement, and the polarization conversion rate is above 90% in the frequency range of 5.5-11.1 GHz. The physical mechanism of the broadband linear polarization conversion effect could be further illustrated by simulated electrical field and surface current distributions.

Dual-Band Circular Polarizer and Linear Polarization Transformer Based on Twisted Split-Ring Structure Asymmetric Chiral Metamaterial

“…CMMs are of great current interest both for customized functionalities and for potential applications not found in natural medium arise from the magneto-electric cross coupling of chiral structures due to their lack of any mirror symmetry. As a fact, besides negative refractive index, CMMs can also achieve other exotic EM characteristics, such as giant gyrotropy [4], strong polarization rotation (giant optical activity) [5][6][7][8][9][10][11], circular polarizer (circular dichroism, CD effect) [12][13][14][15], asymmetric transmission (AT) effect [16][17][18][19][20][21], linear or/to circular polarization conversion [22][23][24][25][26][27][28][29][30][31][32], and even the prospect of a repulsive Casimir force [33,34] by special enantiomeric forms or similar chiral structure design. The cross-coupling is original physics of these special electromagnetic (EM) properties [35,36].…”

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

“…At resonances, all the field patterns will be twisted inside the slab as a consequence of interlayer longitudinal magnetic dipole to magnetic dipole coupling or transverse electric dipole to electric dipole coupling [11,14,18,36,42,43]. Furthermore, the EM fields within metallic layers can be rigorously expressed as series of eigenmodes of the SRRs [41]. From Figs.…”

“…On the other hand, η characterizes polarization state of the transmitted wave and also measures the CD effect due to the difference of RCP and LCP waves in magnitudes. Polarization azimuth rotation angle θ and ellipticity angle η for the normal incident wave can be expressed by the following formulas [17,41]:…”

“…1(a), the designed CMM is composed of three metallic layers and two dielectric spacer layers from the top to bottom layers. Similarly to the unit cell structure configuration in [11,41], the split direction of DSRRs is rotated in a certain angle α along axial direction. The DSRRs in the two layers are coaxial but mutually twisted by α = 45 • .…”

“…However, multi-band or bandwidth expansion is still a main concern which needs improvement. An effective method is stacking metallic-dielectric multilayer planar structure [40], which gives some new ideas for multi-band or broadband device design for polarization transformation [11,25,40,41].…”