Enhancement of spin components' shifts of reflected beam via long range surface plasmon resonance

In this letter, we investigated the impact of long range surface plasmon resonance (LRSPR) on the spatial and angular shifts of left and right spin components of a p-polarization Gaussian beam reflected from a glass-fused silica-gold-fused silica interface, and deduced the formulas of these shifts. We found that the spatial and angular spin splitting of left and right spin components only occur in the direction perpendicular to the plane of incidence (out-of-plane), but not in the direction parallel to the plane of incidence (in-plane). The spatial and angular in-plane shifts of left and right spin components are the same, which are equal to those of the total reflected beam (i.e., angular and spatial Goos-Hänchen shifts). We found that all the in-plane and out-of-plane shifts can be greatly enhanced by LRSPR. The maximum angular and spatial in-plane shifts can be up to 1.060×10−4 rad and 249.977 μm, respectively, which are almost equal to half of the divergence angle and beam waist of the incident Gaussian beam. The maximum spatial in-plane shift (about 20.148 μm) is about 5 times larger than the previously reported enhanced value. We also found that the directions and magnitude of angular and spatial in-plane and out-of-plane shifts can be controlled by slightly adjusting the angle of incidence or the thickness of fused silica film or gold film under certain conditions, which may provide a new way for photon manipulation. Furthermore, our work may provide some help for precision measurement of physical and biological parameters and the development of SPR sensing technology.