Abstract <p>Surface plasmon polaritons (SPPs) are coherent electron–plasma oscillations at the interface of materials with opposite dielectric functions. The excitation and propagation of these polariton modes are strongly affected by material dispersion, geometric behaviour and the excitation frequency. In this paper, we studied the excitation of SPPs at metal/lithium niobate (ferroelectric) interfaces and their dispersion characteristics. The plasmonic waveguides with Ag/LiNbO₃ interfaces provide the coupling of ferroelectric properties in to plasmon modes. We observed a marked propagation length, and both geometrical and material dispersion properties which ensure a sensitive plasmonic system operating at plasmon frequencies.</p>