Tunable Plasmon Molecules in Overlapping Nanovoids

Coupled and shape-tailored metallic nanoparticles are known to exhibit hybridized plasmon resonances. This Letter discuss the optical properties of a complementary system formed by overlapped nanovoid dimers buried in gold and filled with silica. This is an alternative route for plasmon engineering that benefits from vanishing radiation losses. Our analysis demonstrates the possibility of designing artificial plasmon molecules on the basis of void plasmon hybridization, which allows fine mode tuning by varying the overlap between voids. The proposed structures could find application to both signal processing through buried optical elements and tunable-plasmon biosensing.