Abstract
We present a simple design of a broadband tunable metamaterial absorber (MMA) in the terahertz (THz) region, which consists of a single layer complementary gammadion-shaped (CGS) graphene sheet and a polydimethylsiloxane (PDMS) dielectric substrate placed on a continuous metal film. The Fermi energy level (Ef) of the graphene can be modulated dynamically by the applied DC bias voltage, which enables us to electrically control the absorption performance of the proposed MMA flexibly. When Ef = 0.8 eV, the relative bandwidth of the proposed MMA, which represents the frequency region of absorption beyond 90%, can reaches its maximal value of 72.1%. Simulated electric field distributions reveal that the broadband absorption mainly originates from the excitation of surface plasmon polaritons (SPPs) on the CGS graphene sheet. Furthermore, the proposed MMA is polarization-insensitive and has wide angles for both transverse-electric (TE) and transverse-magnetic (TM) waves in the broadband frequency range. The broadband absorption capacity of the designed MMA can be effectively adjusted by varying the Fermi energy level of graphene. Lastly, the absorbance of the MMA can be adjusted from 42% to 99.1% by changing the Ef from 0 eV to 0.8 eV, which is in agreement with the theoretical calculation by using the interference 41theory. Due to its simple structure and flexible tunability, the proposed MMA has potential application prospects in tunable filtering, modulators, sensing, and other multispectral devices.
Highlights
Terahertz wave metamaterial absorbers (MMAs) have recently attracted great attention and become one of the widespread research hotspots due to their promising applications in communication, imaging, detection and sensing, and stealth [1,2,3,4,5]
We propose a novel MMA based on a periodic patterned graphene structure, which can achieve polarization-insensitive and wide-angle broadband terahertz absorption with flexibly active tunability
We have demonstrated a new efficient route for achieving a broadband terahertz tunable MMA using a net complementary gammadion-shaped (CGS) graphene sheet deposited on a PDMS dielectric spacer supported by a metallic reflecting plate
Summary
Terahertz wave metamaterial absorbers (MMAs) have recently attracted great attention and become one of the widespread research hotspots due to their promising applications in communication, imaging, detection and sensing, and stealth [1,2,3,4,5]. We propose a novel MMA based on a periodic patterned graphene structure, which can achieve polarization-insensitive and wide-angle broadband terahertz absorption with flexibly active tunability. The absorption characteristics of the proposed MMA are analyzed by varying the oblique incident angles of terahertz waves and the Fermi energy level of the graphene as well. Numerical results indicate that the relative bandwidth, which presents the frequency range of absorption beyond 90%, can reach its maximum value of 72.1% when Ef = 0.8 eV Both simulation and calculation results reveal that the MMA maintains excellent absorption performance when the incident angle is below 50◦ for both transverse electric (TE) and transverse magnetic (TM) polarized terahertz waves.
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