Design of a Broadband Tunable Terahertz Metamaterial Absorber Based on Complementary Structural Graphene

Abstract

We present a simple design for a broadband tunable terahertz (THz) metamaterial absorber (MMA) consisting of a complementary cross-oval-shaped graphene (CCOSG) structure and dielectric substrate placed on a continuous metal film. Both numerical simulation and theoretical calculation results indicate that the absorbance is greater than 80% from 1.2 to 1.8 THz, and the corresponding relative bandwidth is up to 40%. Simulated electric field and power loss density distributions reveal that the broadband absorption mainly originates from the excitation of continuous surface plasmon resonance (SPR) on the CCOSG. In addition, the MMA is polarization-insensitive for both transverse-electric (TE) and transverse-magnetic (TM) modes due to the geometry rotational symmetry of the unit-cell structure. Furthermore, the broadband absorption properties of the designed MMA can be effectively tunable by varying the geometric parameters of the unit-cell and chemical potential of graphene. Our results may find promising applications in sensing, detecting, and optoelectronic-related devices.

A Broadband Tunable Terahertz Metamaterial Absorber Based on Single-Layer Complementary Gammadion-Shaped Graphene

“…In addition, e represents the charge of an electron,h is the reduced Planck's constant, and k B is the universal constant representing the Boltzmann constant. The approximate estimated theoretical relation between E f and V g can be expressed as [30,45]:…”

“…The most attractive property is that the permittivity and conductivity of graphene can be dynamically tuned by changing the Fermi energy through chemical doping or external bias voltage, achieving dynamically tunable MMAs [19][20][21].In the last few years, MMAs based on graphene have received increasing interest and have achieved tremendous progress. Various MMAs based on patterned graphene structures, such as disks [21], ribbons [22,23], patches [24], cross fishnets [25], and other microstructures [26][27][28][29][30][31], have been proposed to enhance the absorption. It is believed that the perfect absorption of the graphene-based MMA is mainly originated from excitation of surface plasmon resonances (SPRs) in the periodic patterned graphene structures.…”

A photoexcited switchable tristate terahertz metamaterial absorber

“…Recently, special attention has been paid to switchable /tunable metamaterial (MM) absorbers due to their flexibility and fabricability in practical applications . Conventional absorbers operate at frequency‐fixed absorption mode once manufactured unless the structure parameters are altered .…”

“…Some feasible methods such as thermal control, electrical control, and optical control have been proposed to realize switchable or tunable absorbers according to respective requirements. Related to these methods, semiconductor materials, graphene, and some phase‐change materials, such as germanium antimony telluride (GST) and vanadium dioxide (VO 2 ), have become important choices for realization of switchable /tunable devices . By incorporating these materials in the resonators, one can regulate the resonance characteristics through adjusting the conductivity of these materials by temperature, bias voltage, or optical power.…”

Polarization-Independent Wide-Angle Terahertz Metamaterial Absorber: Design, Fabrication and Characterization

“…Others have developed broadband THz MAs using methods such as a stack of many metamaterial layers, different material sizes in a unit cell, and a special pattern design in a unit cell [25][26][27][28]. In order to achieve frequency-adjustable absorption in a single device, the THz MAs with resonance frequency tunability are widely studied with different techniques such as those in the photoexcitation, liquid crystal, and thermal-based MAs [29][30][31][32][33].…”