Tunable Metasurface Activizer Intergrated With Graphene

Tuning the chiral optical response of a structure is crucial for detecting the material’s chirality. Nowadays, we mainly detect the chiral optical response by metasurface activizer. In previous work, the way to tune the chiral optical response is changing the structure of metasurface, which is inflexible can only gain weak response. Note that achiral metasurface consists of metamolecule is more simplified and easier to realize compared to chiral metasurface, since it’s able to detect chiral optical response using both chiral and achiral metasurface. So, it’s imperative to design a tunable achiral metasurface activizer to enhance the chiral optical response.In this work, we gain a pronounced chiral optical response by a three-layered achiral metasurface activizer bansed on graphene. Here, we use the circular polarization conversion difference(CPCD) which is an extrinsically 2D chirality originates from the mutual orientation between achiral metasurface(AMS) and oblique incident wave as a detecting parameter. The main work is as follows: Design a metasurface consisting of metal/dielectric/metal- circular holes array(MDM-CHA), then further incorporate a graphene sheet with the AMS, and electrically modulating the graphene’s Fermi level to tune the CPCD spectra in the mid-infrared(MIR) region. The optimal model is gained by structural design and optimization. The simulation of this three-layered structure shows a promising candidate for controlling electromagnetic waves in the MIR region from 1500 to 3000 nm. Meanwhile, this approach offers a simple processing technology and high fabrication tolerance. This highly symmetric AMS with the large CPCD may be operated as flat lenses, chiral sensing and highly efficient activizers.