Giant intrinsic chiro-optical activity in planar dielectric nanostructures

Abstract

The strong optical chirality arising from certain synthetic metamaterials has important and widespread applications in polarization optics, stereochemistry and spintronics. However, these intrinsically chiral metamaterials are restricted to a complicated three-dimensional (3D) geometry, which leads to significant fabrication challenges, particularly at visible wavelengths. Their planar two-dimensional (2D) counterparts are limited by symmetry considerations to operation at oblique angles (extrinsic chirality) and possess significantly weaker chiro-optical responses close to normal incidence. Here, we address the challenge of realizing strong intrinsic chirality from thin, planar dielectric nanostructures. Most notably, we experimentally achieve near-unity circular dichroism with ~90% of the light with the chosen helicity being transmitted at a wavelength of 540 nm. This is the highest value demonstrated to date for any geometry in the visible spectrum. We interpret this result within the charge-current multipole expansion framework and show that the excitation of higher-order multipoles is responsible for the giant circular dichroism. These experimental results enable the realization of high-performance miniaturized chiro-optical components in a scalable manner at optical frequencies.

Spin-preserving chiral photonic crystal mirror

“…8 On the other hand, the need for an in-plane magnetic moment is eliminated for obliquely incident light, which is commonly termed as extrinsic chirality. 25,26 Recently though, Zhu et al 8 reported an experimental observation of a giant intrinsic chiroptical effect in an optically thin metasurface composed of a periodic array of chiral gammadion-shaped meta-atoms arranged on a dielectric slab. This metasurface selectively transmits only one spin state of light while diffracting the opposite spin.…”

Reconfigurable metasurface hologram by utilizing addressable dynamic pixels

“…With tailored artificial subwavelength building blocks, metasurfaces are able to manipulate the local and far-field light, thus enabling a new generation of ultrathin optical elements with a broad range of functionalities [1][2][3][4][5][6][7][8]. By utilizing metasurfaces as information carriers, metasurface holograms are able to store and reconstruct full wave information of target objects.…”

Optomechanics of Chiral Dielectric Metasurfaces

“…Wavelength‐scale patterns of scatterers have shown the capability to produce bright colors and extravagant surface effects, often mocking what elegantly realized in biological systems . In particular, nanostructuration techniques, combined with powerful ab initio design tools, allow to develop materials which show a chiral response far larger than their natural counterparts, i.e., stereochemical compounds …”