Thermally tunable broadband terahertz metamaterials with negative refractive index

A thermally tunable broadband metamaterials with negative refractive index (NRI) is investigated in terahertz (THz) region theoretically. The metamaterials is designed by fabricating two stand-up opposite L shape metallic structures on fused quartz substrate, and the indium antimonide (InSb) is filled in the bottom gap of the two L shape structures. The tunability is attributed to the InSb because the InSb can changes the capacitance of the gap area by adjusting the temperature. The transmission characteristics and the retrieved electromagnetic parameters of the metamaterials are analyzed. Results indicate that the resonant frequency and amplitude modulation of the metamaterials can be tuned continuously in broadband range (about 0.62 THz), and the phase modulation from -2 to 3 rad is also achieved within broadband range (about 0.8 THz). In addition, the metamaterials shows dual-band NRI behaviors at 0.4-0.9 THz and 1.06-1.15 THz when the temperature increases to 400 K. The wedge-shaped prism simulations are implemented to verify the NRI characteristics and indicate that the NRI of the metamaterials can be achieved. (C) 2017 Elsevier B.V. All rights reserved.