Abstract
Metallic electric split-ring resonators (SRRs) with featured size in micrometer scale, which are connected by thin metal wires, are patterned to form a periodically distributed planar array. The arrayed metallic SRRs are fabricated on an n-doped gallium arsenide (n-GaAs) layer grown directly over a semi-insulating gallium arsenide (SI-GaAs) wafer. The patterned metal microstructures and n-GaAs layer construct a Schottky diode, which can support an external voltage applied to modify the device properties. The developed architectures present typical functional metamaterial characters, and thus is proposed to reveal voltage adjusting characteristics in the transmission of terahertz waves at normal incidence. We also demonstrate the terahertz transmission characteristics of the voltage controlled Fabry-Pérot-based metamaterial device, which is composed of arrayed metallic SRRs. To date, many metamaterials developed in earlier works have been used to regulate the transmission amplitude or phase at specific frequencies in terahertz wavelength range, which are mainly dominated by the inductance-capacitance (LC) resonance mechanism. However, in our work, the external voltage controlled metamaterial device is developed, and the extraordinary transmission regulation characteristics based on both the Fabry-Pérot (FP) resonance and relatively weak surface plasmon polariton (SPP) resonance in 0.025-1.5 THz range, are presented. Our research therefore shows a potential application of the dual-mode-resonance-based metamaterial for improving terahertz transmission regulation.
Highlights
INTRODUCTIONTerahertz waves according to the equivalent LC resonance[7] or the dipole resonance of metallic SRRs.[7,8] Generally, the LC resonance-based metamaterials can support narrowband magnitude regulation, and the dipole-based resonance can provide narrowband and broadband manipulation approaches in typical terahertz range.[8] Recently, researchers have paid much attention to creating functional metamaterials for extraordinary transmission
Over the past decades, the controllable properties of fabricated metamaterials have been used to manipulate electromagnetic radiation in terahertz region
The arrayed metallic SRRs are fabricated on an n-doped gallium arsenide (n-GaAs) layer grown directly over a semi-insulating gallium arsenide (SI-GaAs) wafer
Summary
Terahertz waves according to the equivalent LC resonance[7] or the dipole resonance of metallic SRRs.[7,8] Generally, the LC resonance-based metamaterials can support narrowband magnitude regulation, and the dipole-based resonance can provide narrowband and broadband manipulation approaches in typical terahertz range.[8] Recently, researchers have paid much attention to creating functional metamaterials for extraordinary transmission. The main microfabrication processes of the device above have been described previously.[8] The metal and n-GaAs layers, which already form a Schottky junction, can be considered as a Schottky diode to support an external voltage so as to modify the device properties, such as the carrier density in the depletion zone[7] and the dielectric properties of the metallic SRRs’ array.[7] Through our experiments, a functional metamaterial model is proposed to present the voltage adjusting characteristics during the transmission of terahertz waves. Our research shows several potential applications for improving terahertz transmission regulation
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