Research On The Property Of Long Range Surface Plasmon Resonance

It is clear that Lang range surface plasmon becomes a focus these days in the foreign research. But we couldn't find more reports about that and hardly seen any systematic elaborations and analysis. In this paper the dispersion relation of Lang range surface plasmon and the electromagnetic field's distribution are elaborated analyzed.Surface plasmon modes, resonantly excited at the two sides of an ultra thin noble metal layer in contact with two nearly identical dielectric media interact via the overlap of their electromagnetic fields resulting in two new coupled modes, i.e., a short range and a long range surface plasmon (SRSP,LRSP), respectively. For sufficiently thin metal films, the propagation loss of LRSP is significantly reduced compared to uncoupled SPP waves and, furthermore, LRSP in metal stripe waveguides can be directly excited using standard optical fibers with low coupling loss using the end-fire method. LRSP waveguides based on thin metal stripes have been used to realize a range of integrated optical devices but these still suffer the limitation of only allowing propagation of TM polarized light.We could find that the reflection angle spectrum of LRSP have deeper resonance peak and narrower half width, which showed that LRSP mode is more sensitive whit metal surface condition than any other mode, could be using as high accuracy angle measure and medium component analysis. LRSP and SRSP mode have infinite resolutions in the symmetric three-layer structure, but we are manly concerned about elementary solutions, which almost occupied entirely energy, and other modes have a large effect in satisfying the boundary conditions. Analyses Au, Ag, Cu, Al's elementary solutions respectively with 1.55μm wave, and showed that when metal thickness approach infinite these modes achieve maximum. Finally computed the propagation length of LRSP, SRSP and SPW mode respectively in thickness on 30nm, showed LRSP having superiority.