Figure 4
Refractive index properties of the niobium-based plasmonic taper.
(a) Resonance wavelength as a function of refractive index of the applied liquid. The blue dots refer to the measured resonance wavelength obtained from the dips in the transmission spectra (blue line is a guide-to-the-eye). The green curve shows the results from the planar multilayer model. The shaded green area refers to the potential change in resonance wavelength if a niobium thickness uncertainty of ±1 nm is considered. The inset shows examples of the spectral distribution of selected normalized transmission spectra (values are the RIs of the liquids at λ0 = 589 nm according to the labeling of the used Cargille analytes). (b) Refractive index distribution of the sensitivity of the experimental data (blue) and of the planar multilayer waveguide model (green). The blue dot indicates the sensitivity value at the index of water.
