Dynamic Modulation of Coupled Plasmon Resonances in Antimony-Doped Tin Oxide Nanorod Metamaterial by Charge Carrier Injection

Coupled plasmon resonances of adjacent particles in densely packed nanorod metamaterials can introduce extraordinary optical features, like cavity resonance modes. These modes, being commonly realized in metallic metamaterials, can be exploited for plasmonic sensing or optical modulation, due to strong optical and electrical field enhancement in the cavities. However, modulation of plasmon resonances in metallic nanostructures is limited due to their intrinsically high charge carrier concentration. We introduce a new metamaterial based on metal oxides, respectively an array composed of doped tin oxide nanorods featuring cavity resonance modes. By means of numerical simulations, the optical response of the fabricated plasmonic metamaterial is calculated and compared with the experimental findings in order to understand and clarify the nature of the optical modes. Moreover, dynamic modulation of the optical response is demonstrated by the electrochemical injection of electrons into the nanorods, thus paving the way to electro-optical modulation of such metamaterials.