Theoretical analysis of finite-size surface plasmon polariton band-gap structures

Abstract

Surface plasmon polariton (SPP) band-gap (BG) structures with finite-size gold scatterers arranged periodically on a gold-air interface are analyzed theoretically by making use of the Lippmann-Schwinger integral equation method. Transmission and reflection of SPP waves being incident on 450-nm-period triangular lattice structures are investigated with respect to the size of cylindrical scatterers in the wavelength range 700--900 nm. It is found that 50-nm-high and 125-nm-radius scatterers ensure low transmission and high reflection for both main orientations of the lattice at wavelengths close to 800 nm, indicating that the structure possesses a complete (in-plane) BG for SPP waves. Electric field magnitude distributions calculated above the scattering structure illustrate SPP transmission and reflection for different wavelengths as well as the effect of out-of-plane scattering resulting in non-SPP waves propagating away from the surface. Transmission spectra and field distributions are also presented for wave guides obtained by removing a number of rows of scatterers in the SPPBG structures. The results obtained are discussed and compared with the available experimental and theoretical results. Finally, the possibilities for SPP guiding around sharp bends with relatively low insertion loss are considered.