Effect of a proximal substrate on plasmon propagation in silver nanowires

We investigate how the properties of a nearby substrate modify the excitation and propagation of plasmons in subwavelength silver wires. With decreasing nanowire-substrate separation, the in-coupling efficiency shows strongly oscillatory behavior due to coherent interference. The plasmon damping increases with decreasing separation due to an increased coupling of the nanowire plasmons to the photonic modes of the substrate.