Destroyed-toroidal-localized-spoof-plasmon-induced Fano resonance in plasmonic metamaterial for self-reference plasmonic sensor

Abstract

A novel destroyed-toroidal-localized-spoof-plasmon-induced Fano resonance structure is proposed. Numerical and experimental results reveal that Fano resonance can be excited, when the toroidal-localized-spoof plasmons are destroyed by introducing magnetic dipoles; Fano resonance results from the mutual coupling between the magnetic and toroidal dipoles. The Q-factor and the resonance intensity are investigated, and a larger value of the figure of merit is obtained by increasing the number of magnetic dipoles. Additionally, it is experimentally demonstrated that Fano resonance is sensitive to the background medium. By the introduction of double magnetic dipoles, a self-reference plasmonic sensor is realized. The double magnetic dipoles are independent of each other; one of the magnetic dipoles is used for detection, whereas the other is used as the reference signal, significantly reducing the error contribution of unstable and complicated environments. Hence, Fano resonance can be applied in plasmonic sensors, with potential applications in microwave and terahertz frequencies.