Refractive index sensitivity of gold double concentric nanoshells: Tuning the intensity discrepancy of two-band plasmonic absorption

Refractive index sensitivity of gold double concentric nanoshells based on plasmonic absorption intensity has been investigated by using the quasistatic calculation. Increasing the environmental dielectric constant leads to the absorption intensity of | ω − − 〉 mode gets intense, whereas the absorption intensity of | ω − + 〉 mode fades down. Thus the intensity discrepancy between the two-band plasmonic absorption is greatly dependent on the environmental dielectric constant, which could be used in the refractive index sensing. Furthermore, the sensing ability can be improved by decreasing the thickness of the inner gold shell or increasing the thickness of the outer gold shell. A mechanism based on inter-shell plasmonic coupling and local electric field dependent surface charge density was investigated to illuminate the different effects from inner and outer gold shell on the refractive index sensitivity.