Numerical simulations of the optical properties of SiO2@Au core–shell nanoparticles: The effect of geometrical parameters on the tunability and sensitivity of their plasmon response

Based on systematic numerical simulations, the effect of geometrical parameters of SiO2@Au core-shells (nanoshells) on the tunability and sensitivity of their optical response was elucidated. The surface plasmon resonance (SPR) of nanoshells experiences a blueshift-redshift crossover with the increase in shell thickness, and this phenomenon is ascribed to the competition between the two effects, that is, the hybridization effect dominated in the thin shells and the retardation effect dominated in the thick shells. The relative strength of absorption/scattering in the extinction spectra and the relative strength of dipolar/multipolar modes can be selectively tuned by controlling the total volume of nanoshells. The sensitivity of the SPR peak wavelength to the shell thickness is primarily dependent on the core-to-shell ratio; the higher this ratio is, the larger the sensitivity. The tailorable properties of nanoshells make them promising and well-suited platforms in various applications.