Abstract
Terahertz reflection behaviors of metallic-grating-dielectric-metal (MGDM) microcavity with a monolayer graphene embedded into the dielectric layer are theoretically investigated. A tunable wideband reflection dip at about the Fabry–Pérot resonant frequency of the structure is found. The reflectance at the dip frequency can be electrically tuned in the range of 96.5% and 8.8%. Because of the subwavelength distance between the metallic grating and the monolayer graphene, both of the evanescent grating slit waveguide modes and the evanescent Rayleigh modes play key roles in the strong absorption by the graphene layer. The dependence of reflection behaviors on the carrier scattering rate of graphene is analyzed. A prototype MGDM-graphene structure is fabricated to verify the theoretical analysis. Our investigations are helpful for the developments of electrically controlled terahertz modulators, switches, and reconfigurable antennas based on the MGDM-graphene structures.
Highlights
Graphene is a single flat sheet of carbon atoms connected by sp2 C–C bonds and arranged in the two-dimensional (2D) honeycomb crystal structure [1]
We propose a new absorber/modulator structure, a metallic-gratingdielectric-metal (MGDM) microcavity with a monolayer graphene sheet embedded into the dielectric layer
Our results clearly demonstrate the near-field effects on the electromagnetic interactions between the periodic metallic structure and the graphene sheet, which is very useful for realizing graphene-based tunable functional devices working in microwave and terahertz frequency regions
Summary
Graphene is a single flat sheet of carbon atoms connected by sp C–C bonds and arranged in the two-dimensional (2D) honeycomb crystal structure [1]. In order to enhance the fieldgraphene interactions, various structures, for example, graphene-dielectric stacks [10,11], metal-graphene hybrid periodic structures [12,13,14,15,16,17,18,19,20,21], patterned graphene nanoribbons and patches [22,23,24,25,26,27], photonic crystal microcavity integrated with graphene sheet [28,29], and dielectric waveguide covered by graphene layer [30,31], were proposed and fabricated In these structures, because of the near-field interaction, resonant local electric field enhancement, and the excitation of surface plasmon polaritons (SPPs), strong electromagnetic field-graphene interactions are achieved [9,32]. Our results clearly demonstrate the near-field effects on the electromagnetic interactions between the periodic metallic structure and the graphene sheet, which is very useful for realizing graphene-based tunable functional devices working in microwave and terahertz frequency regions
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