Surface plasmon resonance detection based on a phase method in the spatial domain

Abstract

A phase detection method is proposed and demonstrated to measure the response of surface plasmon resonance (SPR) in the spatial domain. In an experimental setup comprising a laser source, a launching optics, a gold coated SF10 glass plate, a coupling prism, a Wollaston prism and a CCD camera, a spatial interference fringes are recorded. Two such spatial interferograms, one including interference of p- and s-polarized waves from the SPR structure for air when the SPR phenomenon does not occur, and the other one for an analyte when the SPR phenomenon occurs, are used to detect the SPR phase shift at the source wavelength. The interferometry setup is used to measure the SPR phase shift for aqueous solutions of ethanol. The measurements are accompanied by theoretical modeling of the SPR responses using the material characteristics, that is, the refractive index of the SF10 glass, the complex refractive index of gold, and the refractive index of the analyte.