Focusing the non-monotonic shift of concentric double gold nanoshell by tuning the inter-shell plasmonic coupling

We theoretically studied the surface plasmon resonance (SPR) absorption spectra of concentric double gold nanoshell with sub-50 nm diameter. The absorption spectra and the local electric field were calculated based on quasi-static approximation. By tuning the outer radius of inner shell and the inner radius of the outer shell of the double gold nanoshell, the SPR peaks could shift nonmonotonically. On the other hand, tuning the inner radius of inner shell and the outer radius of the outer shell could lead to the SPR peaks shift monotonically. At last, the physical mechanisms of these results have also been illustrated by analyzing the enhancement and distribution of local electric field in the double nanoshells.