For the sake of optimizing its measure range,sensetivity and linearity,a tapered Surface Plasmon Resonance(SPR)fiber probe was applied as the substitution of the uniform fiber probe because of its abundant lossy modes.Simulation results and experimental data shew that this tapered probe had a SPR asorption spectrum with better symmetry and its resonance wavelength could change responsing to a bigger range of measured refractive index with a stable wavelength resolution.After constructing a closed-loop SPR f...