Bend loss in surface plasmon polariton band-gap structures

Using near-field optical microscopy, we investigate propagation of surface plasmon polaritons (SPPs) excited in the wavelength range of 720-830 nm at a corrugated gold-film surface with areas of 200-nm-wide and 45-nm-high scatterers arranged in a 410-nm-period triangular lattice containing line defects with double bends. We find that, for similar to2-mum-wide line defects and the wavelength of similar to 740 nm, the double bend losses for bend angles of 15 degrees and 30 degrees are below 2 and 10 dB, respectively. Our data indicate that the bend loss increases approximately quadratically with the bend angle. We also demonstrate splitting and combining of two SPP line-defect modes in a 20-mum-long Y junction. (C) 2001 American Institute of Physics.