Displacement Current Mediated Resonances in Terahertz Metamaterials

Terahertz metamaterials (THz MMs) have been proven to be good candidates for chemical, biological, temperature, strain, and position sensing. However, currently developed thin‐metal‐film‐based split ring resonator (SRR) MMs have relatively low quality factor (Q‐factors), leading to a poor sensitivity, which is one of the obstacles for development of sensors. In order to enhance the Q‐factor, novel THz MMs, nanopillar‐based MMs, are designed, fabricated, and characterized. The nanopillar‐based MMs excite the inductive‐capacitive resonance via desplacement currents, showing a significantly enhanced Q‐factor around 450, which is about 30 times higher than typical thin‐metal‐film‐based MMs. Nanopillar‐based MMs also show 17 times larger frequency shift compared to the metal‐film‐based MMs when the permittivity of the ambient dielectric properties of the MMs changes. Due to high Q‐factor and large frequency shift, the nanopillar‐based THz MMs utilizing displacement current have great potential for highly sensitive chemical and biomaterial detection as well as frequency‐agile THz devices.