Research On Transmission Characteristics Of Surface Plasmon Directional Coupler

Traditional photonic devices are difficult to achieve miniaturization, due to thediffraction limit, either can not interconnect with electronic integrated circuits which hasreached nanoscale now, that seriously hindered the development of photonic integrationtechnology. In recent years, the relevant principle and application on surface plasmons hadbeen widely studied, the size of photonic devices based on surface plasmons are reducedto the nanometer scale, that are much smaller than the wavelength of light.Directional coupler is a basic structure in photonic integrated devices, widely used inwaveguide coupling, filtering, polarization selection, modulation, optical switchers andlasers and so on. Study on surface plasmon directional coupler has important significancein production of miniaturized photonic devices and realization of large-scale photonicintegration.The transmission characteristics of surface plasmon directional coupler were mainlystudied in this paper. First, the basic properties of the surface plasmons and surfaceplasmon waveguides were introduced, which focuses on the metal-dielectric-metal surfaceplasmon waveguide and its dispersion relation, propagation length, proerties ofelectromagnetic field distribution and so on; second, directional coupler based on surfaceplasmon slot waveguide was studied, We verified surface plasmonic directional coupler inthree-dimensional structure couple through the insulator of substrate and cladding mainlyand the coupling strength is better than that in two-dimensional structure,electromagneticfield distribution of directional coupler was simulated, And the relationship betweencoupling length and structural parameters of directional coupler was analysed; last, a kindof surface plasmon directional coupler in which metal strip between the two adjacentwaveguides is thinner than the metal film was designed, and analysed it with finitedifference time-domain method. The dependences of coupling length on the height ofmetal strip are discussed Results show this sub-wavelength of directional coupler can be applied in the photonic integration technology based on surface plasmons．...