Mid‐infrared Plasmonic Resonances in 2D VO2 Nanosquare Arrays

Plasmon resonances on 2D nanosquare arrays and their temperature‐dependent modulations are demonstrated using the insulator‐to‐metal transition (IMT) of VO2. A comparison between observed experimental trends and electromagnetic simulations reveals that the plasmon coupling is effective in the periodic 2D alignment of metallic VO2 nanosquares and results in a collective plasmon excitation. This plasmon excitation affects the optical responses of VO2 nanosquares in the mid‐infrared (IR) range through reduction of plasmon damping in relation to the specific band structure of VO2. This preliminary understanding is important for the elucidation of temperature‐dependent plasmon resonances. The IMT of VO2 produces temperature‐dependent plasmon resonances with respect to spectral features. The electrodynamic simulations reveal that these phenomena are based on plasmon coupling in the nanosquare array when each nanosquare acts as a single metallic domain. The hysteretic plasmon resonances are derived from resonant coupling between metallic VO2 nanosquares via the IMT nature of VO2, which results in temperature‐dependent changes in collective plasmon excitations in the nanosquare array.