Polarization property associated with surface plasmon resonance in a metal grating in a conical mounting and its...

We focus on the normalized Stokes parameter s₃ of the specularly reflected light from a metal grating in a conical mounting in order to accurately and sensitively detect the occurrence of surface plasmon resonance (SPR). Experimental and theoretical investigations into the incident angle dependence of s₃ reveal a rapid change in s₃ around the resonance angle θ at which SPR occurs. The rapid change in s₃ has features that are successfully applied to SPR sensing: the zero-crossing point of s₃ determines θ, and s₃ in the vicinity of θ varies markedly in response to a small change in the refractive index of a sample. An experiment using gas samples demonstrates that SPR sensing that considers the rapid change in s₃ clearly detects a refractive index change on the order of 10^-5.