A group of the Plasmo-nano-devices Network of Excellence has developped detailed models to investigate surface plasmon polariton band-gap (SPPBG) 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 have been investigated with respect to the size of cylindrical scatterers in the wavelength range 700 900 nm. It was 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 sin-planed BG for SPP waves. Electric field magnitude distributions calculated above the scattering structure provide more insights into SPP transmission and reflection for different wavelengths as well as the effect of out-ofplane 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. This work demonstrates the possibilities for SPP guiding around sharp bends with relatively low insertion losses, which opens interesting possibilities for optical integration using plasmons.

Electric field magnitude calculated 300 nm above the air-gold interface at the wavelength 800 nm for a sharp 30° bend created by removing scatterers sheight h=50 nm, radius r=125 nm in a SPPBG structure.

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Images courtesy of Prof. S. I. Bozhevolnyi, Department of Physics and Nanotechnology, Aalborg University, Denmark.