NEW ANALYTICAL TECHNIQUE FOR CHARACTERIZATION OF THIN-FILMS USING SURFACE-PLASMON RESONANCE

A theoretical technique is presented for simultaneously determining the thickness and dispersive refractive index of a homogeneous thin film applied to a surface plasmon resonance sensor. The technique has the potential for real-time characterization of film parameters while immersed in air, vacuum or liquid media. Experimental realization requires a calibrated wavelength-modulated surface plasmon resonance sensor that is measured at several angles of illumination. A fine-tuned numerical model is used to generate general solutions that describe the sensor response for each angle of illumination. A differential technique and an assumption of a linear dispersion are used to produce a unique solution for the thickness and dispersive refractive index of the film. For a simulated 183 nm thick glass film, results shows 1% thickness prediction error and refractive index prediction error on the order of 3 X 10(-3).