Abstract: Taking sample’s absorption property into consideration and introducing an imaginary part of its refractive index, we have analyzed the dependence of the phase difference of surface plasma resonance (SPR) on the sample attenuation coefficient. It was validated experimentally. Under the optimized operating condition for transparent samples, the changing rate of the phase difference curve near the resonance angle was reduced with the enhancement of the sample’s attenuation coefficient. This degrades sensitivity of phase detection of the SPR based sensors. Nonetheless, it can be effectively compensated for by simply adjusting the thickness of Au film.

Key words: surface plasma resonance (SPR), attenuation coefficient, phase difference, sensitivity