Effect of dipole location on profile properties of symmetric surface plasmon polariton mode in Au/Al 2 O 3 /Au waveguide

This study uses a dipole embedded in Al 2 O 3 layer to excite a symmetric surface plasmon polariton (SPP) mode in Au/Al 2 O 3 /Au waveguide to investigate its profile properties by using finite-difference time-domain (FDTD) method. The excited dipole decay radiatively direct near-field coupling to SPP mode owing to thin Al 2 O 3 layer of 100 nm. The effects of electric and magnetic field intensity profiles and decay length have been considered and characterized. It is found that dipole location is an important factor to influence the horizontal and vertical profile properties of symmetric SPP mode in Au/Al 2 O 3 /Au waveguide. The amplitudes of electric and magnetic field intensity and the wavelengths of metal-insulatormetal (MIM) SPP resonance mode can be tuned by varying dipole location. The horizontal and vertical decay lengths are 19 and 24 nm, respectively. It is expected that the Au/Al 2 O 3 /Au waveguide structure is very useful for the practical applications of designing a SPP source.