Investigation of terahertz high Q-factor of all-dielectric metamaterials

We investigated the propagation properties of all-dielectric metamaterials (ADMs) based on a SiO2-Si asymmetric hybrid block, including the effects of structural parameters, asymmetrical degrees, carrier doping concentrations, and graphene Fermi levels. The Q-factor of Fano resonance reaches more than 270, and the amplitude modulation depth (MD) is about 75% if the asymmetric degree changes in the range of 2–10 μm. The carrier concentration of silicon significantly affects the intensity of excited Fano resonance. When the carrier concentration of Si is 1 × 1014 cm−3, the excited Fano resonance is the strongest, and the transmission peak is about 0.92. With the help of a uniform graphene layer, the Fano resonance can be effectively modulated, the frequency MD is about 20% if the Fermi level changes in the scope of 0.01–0.3 eV. These results can help us to design THz high Q-factor devices, such as sensors, filters, and modulators.