Nondispersive optical activity of meshed helical metamaterials

Abstract

Extreme optical properties can be realized by the strong resonant response of metamaterials consisting of subwavelength-scale metallic resonators. However, highly dispersive optical properties resulting from strong resonances have impeded the broadband operation required for frequency-independent optical components or devices. Here we demonstrate that strong, flat broadband optical activity with high transparency can be obtained with meshed helical metamaterials in which metallic helical structures are networked and arranged to have fourfold rotational symmetry around the propagation axis. This nondispersive optical activity originates from the Drude-like response as well as the fourfold rotational symmetry of the meshed helical metamaterials. The theoretical concept is validated in a microwave experiment in which flat broadband optical activity with a designed magnitude of 45°per layer of metamaterial is measured. The broadband capabilities of chiral metamaterials may provide opportunities in the design of various broadband optical systems and applications.

Near-infrared chiral plasmonic metasurface absorbers

“…However, the high-efficiency chiral absorbers are not attainable from natural materials. Recently, metamaterials and metasurfaces known for exhibiting exotic electromagnetic properties [2][3][4][5][6][7][8][9][10][11] have been designed to achieve highly-efficient selective chiral absorption with various types of three-dimensional (3D) optical structures, such as double-layered L-shaped antennas [13], double-layered twisted crosses [14,15], single-layered double sectors [5], spirals [16][17][18], entangled structures [19,20], and letter-shaped structures [21,22]. Moreover, a deep-learning-based model has been utilized to automatically design and optimize 3D chiral metamaterials [23].…”

Broadband angle- and permittivity-insensitive nondispersive optical activity based on planar chiral metamaterials

“…These phenomena arise due to that, the double layers of CMMs can form a Fabry-Perot-like resonant cavity, and the Fabry-Perot-like resonance will occur when the electromagnetic waves pass through the double layers of CMMs, resulting in the generation of two transmission peaks. Moreover, the Fabry-Perot-like resonant cavity with different space distances will generate different resonant responses, which leads to the transmission spectra altering with the interlayer spacings 48 . Figure 5(c-f) portray the polarization azimuth rotation angle and ellipticity of dual-layer CMMs evolving with different interlayer spacings, respectively.…”

A metasurface‐based broadband quasi nondispersive cross polarization converter for far infrared region

“…Although in the past, few transmittive as well as reflective polarization converters at terahertz region have been reported but either they are narrowband, dispersive, sensitive to angle of incidence, or limited by compactness . Efforts have also been made to design nondispersive polarization converter but they are lossy and suffer from fabrication complexities . Hence, there is still growing interest in designing a broadband nondispersive polarizer having high polarization conversion efficiency.…”

“…[15][16][17][18][19][20][21][22][23][24][25] Efforts have also been made to design nondispersive polarization converter but they are lossy and suffer from fabrication complexities. 26,27 Hence, there is still growing interest in designing a broadband nondispersive polarizer having high polarization conversion efficiency.…”