Modulation and Enhancement of the Localized Surface Plasmon Resonance in Coupling Optical Cavity

Tuning localized surface plasmon resonance (LSPR) in metastructure is widely focused owing to the advanced photonics performance. In this study, a double-layer integrated coupling structure was designed for enhanced local field in infrared region. The structure was constructed using an upper two-dimensional metal grating (TDMG) and a lower optical antenna array. Based on the transmitted field of TDMG analyzing, the arrangement and location of the lower optical antenna array is guided by the TDMG. It can improve LSPR performance of the lower array. Furthermore, the upper and lower discrete metastructures create a dielectric coupling cavity. The cavity resonance mode produced in the cavity coupling enhance the LSPR generated by the optical antenna array, realizing infrared double-band enhancement. The structure enables the formation of cavity resonance modes that effectively modulate and amplify the LSPR generated by the optical antenna array.