Simulation And Study Of Coupling And Tuning In Core-Shell/Crescent Nanoplasmonic Structures

Simulation on surface plasmon resonance shows local field enhancement(LFE) caused by surface plasmon polaritons increases in Au basedmulti-layer shell-core nanosphere compared with a single-layer nanospheredue to intra-layer coupling. Red-shift to the near-infrared is observed bytuning thickness of the layers. Another3D numerical study is presented fora multilayer Au/dielectric/Au nanocrescent structure adhered to a dielectriccylinder. The cavity coupling via the cylinder is found to be dominant intuning the plasmon wavelength. This provides the possibility of tailoringthe device’s plasmon band by adjusting the cylinder’s size and material. Byusing a cylinder with higher permittivity, the plasmon peak significantlyshifts to the near-or mid-infrared regime without increasing the size of thecrescents, thus increase of radiation loss can be fully avoided. Extracrescent layers can also be added to the structure to induce intra-particlecouplings among Au crescents and enlarge the areas of the hot-spots,without shifting the plasmon band. The LFE of the multiple-layer structureis shown to be dramatically increased through the intra-particle couplingamong the Au crescents, compared with a single layer Au nanocrescentstructure. Further increase of LFE can be achieved by substitutingsemiconductors for the dielectrics in the structure due to the chargetransport at metal–semiconductor interfaces.