Fig. 1. Configuration of optical fiber SPR sensors.

Fig. 2. Permittivity of Au and NPM. Squares, Lorent–Drude model; circles, Drude model; solid, real part; open, imaginary part of the permittivity; solid, dash, dot, and dash dot lines are drawn according to εre=εre0−0.065λ, and the values of εre0 are 20, 25, 30, and 35, respectively.

Fig. 3. Normalized transmitted powers corresponding to different values of (a) εim, (b) εre0, and (c) k1.

Fig. 4. Effect of NPM layer thickness.

Fig. 5. Transmitted spectra for the sensing layers with different RIs.

Fig. 6. (a) Resonance wavelengths and (b) FWHMs of optical fiber SPR sensors coated with NPM1, NPM2, and NPM3.

Fig. 7. Dependence of reflectivity on the wavelength and incident angle for different thicknesses of NPM layers.

Fig. 8. Reflected spectra of prism-based SPR sensors corresponding to different values of (a) εim, (b) εre0, and (c) k.

Fig. 9. Reflected spectra of prism-based SPR sensors coated with (a) NPM1, (b) NPM2, and (c) NPM3.

Fig. 10. (a) Resonance angles and (b) FWHMs of prism-based SPR sensors coated with NPM1, NPM2, and NPM3.