CONTROL OF THE DYNAMIC-RANGE AND SENSITIVITY OF A SURFACE-PLASMON RESONANCE BASED FIBER OPTIC SENSOR

The refractive index sensitivity and dynamic range of a recently devel oped fiber optic based surface plasmon resonance sensor have been inve stigated. The sensor response was studied using a set of aqueous refra ctive index standards. The sensitivity to refractive index was found t o be between 5.0 x 10(-4) and 5.0 x 10(-5) index of refraction units. The dynamic range of an unmodified sensor was between 1.25 and 1.40 in dex of refraction units. The dynamic range was tuned for ranges betwee n 1.00 and 1.40 index of refraction units with the addition of thin hi gh refractive index overlayer films. This range is significant since i t includes both gas and aqueous chemical sample refractive indices. Th e upper limit of the refractive index dynamic range was extended to 1. 70 by use of a sapphire fiber core material.