Polarization property associated with surface plasmon resonance in a metal grating in a conical mounting and its application to refractive index sensing

We focus on the normalized Stokes parameter s(3) 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 s(3) reveal a rapid change in s(3) around the resonance angle theta(sp) at which SPR occurs. The rapid change in s(3) has features that are successfully applied to SPR sensing: the zero-crossing point of s(3) determines theta(sp), and s(3) in the vicinity of theta(sp) 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 s(3) clearly detects a refractive index change on the order of 10(-5). (C) 2021 Optical Society of America.