THz response of TiO2 microspheres embedded in a dielectric layer

TiO₂ microspheres embedded in a dielectric layer were investigated both experimentally using time domain terahertz (THz) spectroscopy, and theoretically by finite-difference time-domain method. We focus on the role of the permittivity of the embedding medium. We find that media with sufficiently low permittivities do not significantly affect the effective response of the microspheres, which is a prerequisite for the fabrication of durable metamaterials with fixed spatial distribution of the components.