Fabrication and Performance of $\hbox {TiO}_{2}$ -Ceramic-Based Metamaterials for Terahertz Frequency Range

A two-dimensional dielectric metamaterial composed of a TiO₂ cube array is fabricated, and its performance is characterized in the terahertz region. The effective electromagnetic parameters are retrieved from the complex transmission and reflection coefficients of the sample, obtained using terahertz time-domain spectroscopy. The retrieved parameters show negative permeability and permittivity at around 0.28 and 0.38 THz, respectively. We also show via simulations that negative refractive index metamaterials can be realized by combining two sets of TiO₂ cubes of appropriate sizes. We also propose and fabricate composite structures made of TiO₂ spheres and a metal mesh to obtain a negative refractive index. The observed transmission band is attributed to the negative refractive index. TiO₂ is a promising material for fabricating negative refractive index metamaterials for the terahertz frequency region.