Roughness effect on the SPR measurements for an optical fibre configuration: experimental and numerical approaches

Through numerical simulations supported by an experimental approach, the roughness effects of a gold layer were investigated on the response curves of surface plasmon resonance (SPR) based optical fibre sensors. First, a perturbation term describing the roughness is extracted from the spatial frequency spectrum of the gold surface. This term is then taken into account in the w-k dispersion relationship. Second, an effective dielectric function including the roughness is calculated from experimental data. The response curves were simulated by varying the surface parameters around the experimental ones. The results obtained show that the roughness is a crucial parameter to compare SPR experiments and simulations.