Hybrid electronic-photonic subwavelength cavities operating at terahertz frequencies

Abstract

dimensions as small as λeff/9 in all directions of space (or λ/30 with the vacuum wavelength). We experimentally prove that the capacitance and inductance of these devices are not interdependent, as in purely photonic cavities, but that they can be adjusted almost independently, as in an electronic circuit. This functionality proves that the dimensions of these hybrid electronic-photonic devices are intrinsically not limited by diffraction as in conventional photonic resonators. Using arguments from transmission line theory, we show that it is necessary to include at least one metallic loop in the cavity design to access this regime and we note, as a corollary, that some recent proposals to miniaturize THz resonators and devices beyond the diffraction limit do not meet this fundamental requirement. Our results shed a light on the ability to describe THz/metallic cavities in terms of circuit elements. Furthermore, upon insertion of electrical contacts, these extremely subwavelength resonators can potentially lead to advances in THz detectors and phased array antennas.