Classical and Quantum Surface Plasmon Resonance Biosensing

Figure 2

The dependence of the measured reflectance on the incident angle of light and the analyte’s refractive index. As the angle of incidence of light hitting the prism changes, the intensity of the reflected beam R changes. This is because the incident beam begins to couple with the plasmons in the gold metal exciting them and generating a surface plasmon wave in the process; the energy of the beam is thus converted to this wave, and we start to get a drop in power. As the coupling becomes stronger and the evanescent waves become more intense, the reflected beam becomes weaker until it reaches the minimum point, that is, the resonance dip. (a) SPR dip with resonance angle. The same resonance dip effect can be observed when the incidence angle is kept constant and the refractive index changes instead. This is shown in (b) with an SPR dip plotted against the dielectric material’s refractive index. (c) A 3D representation of the SPR dip is shown, considering the refractive index of the dielectric material and the angle of incidence. In this example, the coupling occurs at an incident angle of and a dielectric material of refractive index and the refractive index of the prism . This was taken from reference [40].

(a)

(b)

(c)