Biosensor based on surface plasmon interferometry independent on variations of liquid’s refraction index

We present a surface sensitive optical sensor based on registration of the phase of surface plasmons by such a method of the phase detection that makes it possible to essentially eliminate an undesirable sensitivity to variations of refraction index of a liquid due to temperature, composition and other changes. This objective has been achieved by detecting the interference between the surface plasmon wave and a bulk wave propagating at grazing angle just above the surface. The proposed interferometric method also does not suffer from vibrational noise.