Design of active nanospheres and plasmon waveguides based on metallic nanoshells

Two innovative nanophotonic structures are designed with the aim of fabricating sensors for biological application. The former is constituted by silica nanospheres activated via erbium doping, which could be covered by a biological material. In the model, the electromagnetic field profile of the Whispering Gallery Modes (WGMs) in the microsphere resonator are analytically investigated for both the pump and the signal wavelengths. The microsphere laser operation has been taken into account by considering the rare earth ion emission via the rate equations. The latter structure is constituted by a plasmon waveguide based on a structured array of metallic nanoshells, composed of a silica spherical core surrounded by a gold shell. This waveguide can provide the electromagnetic energy transport below the diffraction limit via the electromagnetic field coupling between closely spaced nanoshells. A number of simulations have been performed in order to investigate the effects of the geometrical parameter changes on the sensor performance.