The Research Of Grating Modulated Long-range Plasma Excited And Transmission Charactetistics

In recent years, more and more domestic and foreign researchers focused their eyes on study of into the long range surface plasmon waves, and has made considerable achievements in scientific research, more and more people recognize the long-range surface plasmon wave characteristics and advantages. In this paper the excitation and the Bragg grating modulation of Lang rang surface Plasmon waves 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: a short range(SRSP) and a long range surface plasmon(LRSP). 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.Through the analysis of long-range surface plasmon wave modulation Bragg grating excitation and can make people see the relationship between the parameters and the Bragg grating surface plasma waves, can make people Bragg grating by adjusting the parameters, so as to realize the surface excite plasma waves and modulation.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 al most occupied entirely energy, and other modes have a large effect in satisfying the boundary conditions. Analysis of the Bragg grating duty cycle, period and the ratio of refractive index, to determine the effect on the excitation wavelength of the surface plasmon waves, and the length of the transmission and the skin depth of the medium and the metal. The results of the research provide a theoretical basis for LRSP sensors and components production, and laid a foundation for long-range surface plasmon applications.