Dual Schottky Embedded Electronically Reconfigurable Toroidal Resonance

Resonance phenomena play a crucial role in realizing intense light-matter interactions. However, in most resonance driven interactions radiative losses play a spoiling role. In this regard, toroidal resonance offers great promise to realize non-radiating charge current distributions leading to intense electromagnetic field confinements, ultimately negating the radiative losses. However, for real time photonic devices, electronically tunable toroidal modes are fundamental necessity. Hence, we demonstrate electrically tunable dual Schottky embedded toroidal metasurfaces operating in the terahertz (THz) regime. Platinum and aluminium metals on IGZO film simultaneously form the metal resonators for plasmonic metasurface as well as dual asymmetric Schottky contacts in a compact configuration. Such dual Schottky design allows electronically tunable metasurfaces operating in forward and reverse biases which is not feasible with a typical single Schottky contact. Further, our experiments demonstrate relative changes in toroidal mode, ∼19% for 18 V bias which is validated by an analytically derived multipole analysis. Moreover, the experimentally observed resonance modifications are qualitatively explained using voltage controlled Schottky depletion widths established underneath the metasurface resonators. Hence, this work showcases the potential of dual Schottky junctions in realizing electronically controlled compact metasurfaces that can be helpful in implementing miniaturized on-chip THz devices.