Figure 6.

The calculated position of InSb SPR (TM reflectivity minimum) for different settings of the Otto configuration as a function of the refractive of the dielectric (analyte). For each refractive index and the angle of incidence, the thickness of the dielectric and resonance wavenumber are obtained simultaneously. For increasing angle of incidence (increasing propagation constant) the optimum is found for thinner dielectric layer (subplot (a)) and sensitivity to higher refractive indices (subplot (b)). For example, the highest sensitivity for analyte with refractive index 1.3–1.4 is with the angle of incidence of 25° and the resonances would be found in the range 45–55 cm⁻¹. Blue, red and green curves correspond to values of our measurement setup.