Decay and propagation properties of symmetric surface plasmon polariton mode in metal-insulator-metal waveguide

Decay and propagation properties of symmetric surface plasmon polariton (SPP) mode based on metal-insulator-metal (MIM) waveguide are investigated numerically. SPP mode is excited through a dipole embedded in Al2O3 layer of Au/Al2O3/Au structure. We demonstrate that the distance between the dipole and Al2O3/Au interface is an important tunable parameter to influence the decay properties. The electric/magnetic field intensity horizontal and vertical decay lengths of symmetric SPP mode are 19 nm and 24 nm, respectively. Moreover, the propagation length along Al2O3/Au interface of symmetric SPP mode depends on Al2O3 layer thickness. The maximal propagation length reaches 0.608μm with Al2O3 layer thickness of 100 nm. These values can provide a theoretical reference for designing a high-performance SPP source using Au/Al2O3/Au structure.