Terahertz Dielectric Properties of MgO Nanocrystals

Terahertz properties of chemically synthesized MgO nanocrystals are studied by terahertz time-domain spectroscopy in the frequency range extending up to 3.7 THz. The experimentally determined optical and dielectric properties of the nanocrystalline MgO are compared with those of a bulk MgO single crystal. Three prominent resonance modes, which are essentially responsible for the dielectric properties of the nanostructured MgO in the terahertz regime, are characterized at ω 1 /(2π) = 4.26 THz, ω 2 /(2π) = 7.68 THz, and ω 3 /(2π) = 12.18 THz and are well-described by a multiple-oscillator model through theoretical fitting. The MgO nanocrystals may find intriguing applications in developing terahertz quasi-optic components and terahertz spectroscopy.