Ultra-Small Mode Volume Three-Dimensional THz LC Metamaterial

We present a novel architecture for THz metamaterials relying on three-dimensional meta-atoms embedding a semiconductor active region. The meta-atoms behave as inductor-capacitive (LC) resonators with nano-scale capacitive parts, and they have extremely sub-wavelength mode volume (10
^-6
λ
₀
) and surface footprint (10
^-3
λ
₀
²
). When the LC resonators are coupled to a two-dimensional electron gas confined inside the capacitive elements the ultra-strong lightmatter coupling regime is achieved. We also discuss the potential of such structures for ultra-low dark current THz quantum well photodetectors.