Research On Plasmonic Waveguide And Design Of Refractive Index Sensor

ABSTRACT:Future photonic integrated circuits for optical information will have specific requirements on the density of integration. Surface Plasmon Polaritons (SPPs), which can break the diffraction limit of light due to their tight field confinement to the metal surface, shows great promise for applications in highly photonic integrated circuits. Various waveguides and photonic devices based on SPPs have been reported in recent years.This dissertation first presents the dispersive model for metals, and then analyzes the property of SPPs on a single interface between dielectric-metal. Actually the surface Plasmon devices are mostly based on multi-layer metallic structures, so we then analyze the basic modes and characteristics of SPPs in two kinds of multi-layer structures: metal-insulator-metal (MIM) and insulator-metal-insulator (IMI), and give their dispersion equations analytically and show their differences and potential applications. In the following part, we give our simulation results of the long-range surface plasmonic (LRSP) waveguide, dielectric loaded surface plasmonic (DLSP) waveguide, and hybrid surface plasmonic waveguide. Then we changed the symmetry of these structures and analyze the impact on this three kind of waveguides of their fields distribution and properties. The hybrid plasmonic waveguide combines both merits of LRSP and DLSP modes, with high refractive-index contrast; the field of the guided mode is confined more in the two dielectric core layers. In contrast to the previously studied structures, the gap between the slabs and the metal stripe and the associated field enhancement effect result in the dramatically modified modal behavior. It is shown that, under optimized configurations, the transmission loss can be reduced significantly. We proposed a refractive index sensor based on hybrid long range plasmonic waveguide, which is a two-dimensional symmetric hybrid plasmonic waveguide that integrates two high-refractive-index dielectric slabs with a finite-width insulator-metal-insulator (IMI) structure. This structure shows the potential to enable subwavelength confinement in the low index gaps between the dielectric slabs and the metal stripe as well as maintaining the long-range propagation characteristics of the traditional IMI waveguides. It has tremendous sensitivity to its environment. This flat-type sensor in measuring only a few dozen of nanometers thickness of thin film samples have greater advantage, moreover its sensitivity can reach 10"5. At the same time the structure of the refractive index sensors compatible with the photolithography fabrication process and easy to integrate in the high-density photonic integrated circuits, indicating it has a promising future.