Study of surface plasmon resonance sensors based on silver–gold nanostructure alloy film coated tapered optical fibers

Surface plasmon resonance (SPR) based tapered fiber optic sensor having nanostructure film with different particle sizes and volume fractions are analyzed and compared. Using ray-tracing model change in resonance wavelength, propagation length and penetration depth in metal of coupled light are obtained for proposed sensor configuration. The sensitivity of the sensor has been estimated with volume fraction and particle size of nanostructure materials. The sensitivity of the sensor increases with raise in volume fraction along with decline in taper ratio. In addition, the particle size of nanostructure film only affects the detection accuracy. Among all proposed configurations the nanostructures allow film of 2 nm particle size over tapered fiber, shows better detection accuracy and better sensitivity for larger volume fraction of silver.