Theoretical study of tunable chirality from graphene integrated achiral metasurfaces

Abstract

Control of chirality using metamaterials plays a critical role in a diverse set of advanced photonics applications, such as polarization control, bio-sensing, and polarization-sensitive imaging devices. However, this poses a major challenge, as it primarily involves the geometrical reconfiguration of metamolecules that cannot be adjusted dynamically. Real-world applications require active tuning of the chirality, which can easily manipulate the magnitude, handedness, and spectral range of chiroptical response. Here, enabled by graphene, we theoretically reveal a tunable/switchable achiral metasurface in the near-infrared region. In the model, the achiral metasurface consists of an array of circular holes embedded through a metal/dielectric/metal trilayer incorporated with the graphene sheet, where holes occupy the sites of a rectangular lattice. Circular conversion dichroism (CCD) originates from the mutual orientation between the achiral metasurface and oblique incident wave. The achiral metasurface possesses dual-band sharp features in the CCD spectra, which are tuned over a broad bandwidth by electrically modulating the graphene's Fermi level. By selecting aluminium as the metal materials, we numerically achieved strong CCD and considerably reduced materials costs with our nanostructures compared with the typically used noble metals such as gold and silver.

Fundamentals and Applications of Chalcogenide Phase‐Change Material Photonics

“…In this regard, functional materials with either electrically or optically tunable parameters are technologically important and desirable. Over the past few years, more modern materials with tunable optical properties, such as liquid crystals, graphene, electrochromic, vanadium dioxide (VO 2 ), and chalcogenide PCMs have shown promising potentials for controlling the light propagation in nanostructures while maintaining the structures’ geometries. The actively tunable photonic devices certainly exhibit the exceptional advantages of easier manufacturing and cheaper cost over the passively tunable devices that either tune the optical responses by varying the measurement setup or the geometry of the structure .…”

Giant Asymmetric Transmission and Circular Dichroism with Angular Tunability in Chiral Terahertz Metamaterials

“…Asymmetric transmission refers to the transmission difference from different incident side and it focuses on the difference between off‐diagonal elements of Jones transmission matrix . Previous efforts have been concerned on modulating metamaterials symmetry, rotating twist angle of stacked layers, changing anisotropy of loss, and graphene regulated achiral metasurfaces . The previous methods have paid more attention to the formation of asymmetric transmission, but how to enhance the intensity of asymmetric transmission is rarely discussed deeply.…”

Microwave Orbital Angular Momentum Beam Generation Based on Circularly Polarized Metasurface Antenna Array

“…Compared to traditional three-dimensional structures, metasurfaces possess 15 miniature and ultrathin characteristics. Therefore, they are easier to be [16][17][18][19] fabricated and integrated in devices or systems.…”