Propagation Properties Of Two Kinds Of Splitters Based On MIM Surface Plasmonic Waveguides

In this fast-developing information era, the amount of information is increasing exponentially. It is critical to process the vast quantities of information at faster speed. However, it is difficult to further increase the transmission speed in the electronic circuits, owing to the existence of the heating problem and R-C delay problem. Using photons to replace electrons can resolve these problems effectively. It is necessary to control photons in nanometer scale in photonics technology, nevertheless, the scale of current optical circuits are limited in micrometer scale, which brings new challenge to nanophotonics. In recent years, a new idea called surface plasmons(SPs) is attracting more attention. The surface plasmons are electromagnetic excitations which are caused by the interaction between light and free electrons in a metal, and have lateral scale of subwavelength. The SPs, not only overcome the heating problem and R-C delay in electronic circuits, but also beat the diffraction limit in optical circuits, have been honoured as the highest potential information carrier of the nanophotonics components. At present, surface plasmon polariton (SPP)-based waveguides have been a subject of intensive research which are expected to play a major role in the fields of optical integration, optical storage, detectors, modulators, microscopy and so on.In this dissertation, the concept and properties of surface plasmon polaritons are expounded firstly, the current status of metal-insulator-metal (MIM)-based surface plasmonic waveguides and splitters based on surface plasmonic waveguides are discoursed, and the finite difference time domain(FDTD) method is introduced simply. Then we analyze the propagation properties of the1x2and1x4Y-splitters based on MIM surface plasmonic waveguides by using the two-dimensional FDTD(2D-FDTD) method.The main contents include as follows: (1) The dependence of the reflectivity, the transmission rate and the power splitting ratio, on the geometrical parameters of two kinds of1×2Y-splitters with sine shaped and circular shaped arcs respectively, based on MIM surface plasmonic waveguides, are analyzed. Results show that the transmission characteristics of the two Y-splitters are adjusted obviously by the parameter of the width of the waveguides and are effected weakly by the two parameters of the offsets of the two output branches and the lengths of the bends. The transmission characteristics of the Y-splitter whose bends are circular arc-shaped are better than the Y-splitter whose bends are sine arc-shaped within600nm-1500nm wavelength range.(2) The dependence of the reflectivity, the transmission rate and the power splitting ratio, on the geometrical parameters of a symmetric1×4Y-splitter based on MIM surface plasmonic waveguides, are analyzed. Results show that the transmission properties of this Y-splitter is adjusted obviously by the parameter of the width of the waveguides, and on the contrary, is adjusted faintly by the parameters of the offsets of the output branches which are respectively belonging to the first stage and the second stage. The transmission properties of this Y-splitter is also effected weakly by the two parameters of the lengths of the bends and the length of the connected waveguide within600nm-1500nm wavelength range.These studies will provide some theoretical basis for the design, fabrication and application of1×2and1×4Y-splitters.