Abstract
In this paper, we numerically and theoretically study the tunable plasmonically induced transparency (PIT) effect based on the graphene metasurface structure consisting of a graphene cut wire (CW) resonator and double split-ring resonators (SRRs) in the middle infrared region (MIR). Both the theoretical calculations according to the coupled harmonic oscillator model and simulation results indicate that the realization of the PIT effect significantly depends on the coupling distance and the coupling strength between the CW resonator and SRRs. In addition, the geometrical parameters of the CW resonator and the number of the graphene layers can alter the optical response of the graphene structure. Particularly, compared with the metal-based metamaterial, the PIT effect realized in the proposed metasurface can be flexibly modulated without adding other actively controlled materials and reconstructing the structure by taking advantage of the tunable complex surface conductivity of the graphene. These results could find significant applications in ultrafast variable optical attenuators, sensors and slow light devices.
Highlights
Typical electromagnetically induced transparency (EIT) occurs in a coherently driven atomic system, resulting from the destructive interference of two dressed states, and a narrow transparency window is generated simultaneously in a broad absorption spectral region [1,2,3]
We propose a tunable metasurface structure to theoretically and numerically study the plasmonically induced transparency (PIT) effect, which consists of a graphene cut wire (CW) resonator and split-ring resonators (SRRs)
One can see that the incident plane wave directly couples to the graphene CW resonator and a traditional localized surface plasmon (LSP) resonance can be observed at the wavelength around 5.95 μm in the transmission spectra as demonstrated by the solid blue line
Summary
Typical electromagnetically induced transparency (EIT) occurs in a coherently driven atomic system, resulting from the destructive interference of two dressed states, and a narrow transparency window is generated simultaneously in a broad absorption spectral region [1,2,3]. The realization of the traditional quantum EIT requires harsh and unique conditions, namely, stable optical pumping and a cryogenic temperature, which quite constrains further investigations and practical applications [2]. To overcome these barriers, EIT was introduced to metamaterial structures, and the plasmonic analogue of EIT, or PIT (plasmonically induced transparency), based on metamaterial has received significant interest in many fields for its flexible design, no pumping required, room temperature, and easy realization [4,5,6]. Once the metamaterial structures are fabricated, the spectral response and operating frequency will be fixed, which greatly limits its modulation range and scope of application. In order to implement the dynamically adjustable function of the metamaterial structure, it is essential to reconstruct the structural geometries, which is very impractical and difficult once the devices are fabricated
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