Surface plasmon resonance bio- and chemical sensors with phase-polarisation contrast

Abstract Phase-polarisation contrast (PPC) method for the enhancement of the contrast of Surface Plasmon Resonance (SPR) information pattern is proposed and realised. The method consists in the optimisation of the optical scheme for SPR dip visualisation, that makes use of the behaviours of light phase and polarisation under SPR. A converging light beam with a variable polarisation ellipticity is used for surface plasmon excitation, while the reflected beam is analysed by a phase compensator and an analyser. Using the PPC method, we have observed the enhancement of the SPR pattern contrast by more than one order of magnitude in comparison with traditional SPR schemes. This allowed us to increase significantly the accuracy of SPR shift measurements in bio- and chemical sensing and to reduce restrictions on allowable dispersion of parameters of SPR-supporting metal films and binding layers immobilised on them. In addition, the PPC method can provide a gain in sensitivity.