Design of a Dual-band Terahertz Planar Double-Negative Metamaterial with Near Zero Refractive Index Property

Abstract

A new planar square-shaped metamaterial (MTM) structure with dual-band negative refractive index (NRI) and double-negative (DNG) properties in the terahertz regime is proposed in this paper. The MTM unit cell is constructed using identical L-shaped planar resonators and rectangular planar structure over a lead glass substrate. For normal wave incidence, the proposed structure exhibits broad and dual-band NRI properties at 3.08–3.64 THz and 4.10–4.37 THz. Realized NRI bandwidth at these two frequency bands are 0.56 THz and 0.27 THz, respectively. At two distinct frequency bands, 2.85–3.66 THz and 4–4.46 THz, negative effective permittivity is observed. Negative effective permeability and dual-band DNG properties are obtained in the frequency ranges of 3.44–3.62 THz and 4.16–4.21 THz. Acquired bandwidth of these DNG regions are 0.18 THz and 0.05 THz, respectively. Simulated results are indicative of effective utilization of the unit cell in THz applications. The design is appealing in THz applications because of its unique planar design, broad and dual-band NRI and DNG properties. Single negative (SNG) and near zero refractive index (NZRI) properties are also attained in the same environment by this unit cell. NZRI property is acquired over a 1.4 THz bandwidth ranging from 1.68–3.08 THz. This unit cell has potential application in multiple frequency spectroscopy detection of drugs and explosive materials, along with the design of THz directional antennas, cloaking devices, absorbers, modulators, sensors etc.