Research On Mode Characteristics And Dispersion Tailoring Of SPP Fiber Waveguide

With the development of optical communication technique, all-optical devices become a hot spot. Especially the design and development of micro-fiber waveguides have attracted much attention. Furthermore, the characters of Surface Plasmon Polaritons(SPP) in waveguides, with their ability to break the light diffraction limit, have become a desirable manner for the enhancement of nonlinear interactions. Here, we introcuce the SPP to the researches of micro fiber.In the basic theory part, a brief review of different dispersions existed in waveguides, including material dispersion, waveguides dispersion and mode dispersion were presented. From the coupled wave equations, we deduced that the high wavelength conversion efficiency mainly depend on three factors. Firstly, the phase matching condition(PMC) must be fulfilled. Secondly, material with high nonlinear polarization tensor should be used as the nonlinear interaction media. At last, small effective mode area must be realized in order to obtain big nonlinear coefficient.According to the literature research, nanoscale mode field confinement can be realized in plasmon waveguides. In this thesis, two types of SPP fiber waveguide were proposed. One is metal cladded micro fiber, and the other one is metal-dielectric-metal fiber waveguide. Firstly, for the metal cladded micro-fiber waveguide, the influence of metal layer on the mode field distribution, effective mode index and the transmission loss were analyzed. PMC for THG was achieved when the radius of micro-fiber is 1?m. And we have got that the mode effective index curves are not sensitive to the waveguide structure parameters near the PMC point, which is benefit to the realization of nonlinear effect in realistic applications. For the metal-dielectric metal waveguide, the mode dispersion characteristic curve, propagation length and mode confinement were simulated in micron and nanometer scale respectively. In the range of micrometer, by changing the structure parameters, zero-dispersion wavelength can be tailored. In the range of nanometer, performance in four-wave mixing was presented.