Dynamic Plasmonic Metasurface Regulated by Drude‐Like Active Spacers

Integrating resonant optical metasurfaces with active materials is crucial for dynamic modulation of their optical properties. In this work, we demonstrate active modulation of the optical responses of mirror‐coupled plasmonic metasurface integrated with low‐electron‐density Drude (LEDD) spacers. The resonant plasmonic metasurface is based on a conductively linked Au nanodisk dimer meta‐atom that supports bonding dimer plasmon (BDP) and charge transfer plasmon (CTP) resonances. We show that the resonance properties of the integrated metasurface can be actively tuned by modulating the carrier density of the Drude‐like films made of transparent conducting oxides and phase‐change materials. We also show that spacer thickness can play an alternative role in tuning the resonant property of the hybrid plasmonic metasurface. Our comprehensive far‐field spectral analysis results reveal that the CTP mode is sensitive to the carrier density of the Drude‐like films, whereas BDP mode exhibits sensitivity to the spacer thickness. Furthermore, close inspection based on near‐field and charge distributions show that direct charge transfer can take place at the plasmonic meta‐atom and conductive spacer interface. The observed dynamic optical responses of the hybrid metasurface are discussed from the electronic and optical properties of the LEDD spacers. These findings may lay a theoretical foundation for developing active and reconfigurable integrated resonant metadevices.