Surface plasmon polaritons of a symmetric metamaterial slab waveguide with a hollow core for fluid sensing

We present a novel waveguide-type fluid sensor with symmetric metamaterial (MTM) slabs by using surface plasmon polaritons (SPP). The presented fluid sensing slabs, consisting of MTM claddings and a hollow core, are designed to have the SPP mode enhance the sensitivity of the fluid sensor. SPP modes are surface waves propagating along the interfaces and decaying exponentially in the transverse direction of the interfaces and are excited in the slabs when a fluid flows into the hollow core, thereby producing evanescent field intensity higher than that of conventional slabs. The eigenvalues of the guiding modes and the SPP mode were graphically derived by using new dispersion equations in a one-dimensional five-layered structure, and the field distributions of the guiding modes and the SPP mode were developed. By designing the refractive indices and widths of the hollow core, the MTM slabs, and the fluid, we can achieve an evanescent field intensity along the interfaces for the presented SPP fluid sensor.