Measurement of refractive index change by surface plasmon resonance and phase quadrature interferometry

The phase difference change between the s and p polarization lights in surface plasmon resonance sensing systems is strongly influenced by the refractive index of the test sample. In this paper, the phase difference change, measured by common-path phase quadrature interferometry, can be used to estimate the refractive index change. In the experimental results we obtain a phase stability of 0.07°, and a resolving power for the refractive index of 6 × 10−6 RIU. This method has the advantages of a simple optical setup, being easier to operate in real time, and low cost. In addition, due to the common-path arrangement, our method can also eliminate the surrounding noise.