The Research On Surface Plasmon Polaritons Photonic Components Based On Finite Element Method

Surface plasmon polaritons (SPPs), which are electromagnetic waves coherentlycoupled with electron oscillations and propagating at the interface between adielectric and a metal with strong field confinement, have attracted considerableinterest in the area of compact photonic circuits because of their subwavelengthconfinement ability.The ability of SPPs lays the theoretical foundation of high densityon-chip optical integrations. In highly integrated optical communication circuits,photonic components are significant basic elements. Traditional photonic componentsmade of dielectric or semiconductor materials usually suffer from large sizes due tothe optical diffraction limit. Owing to these merits,surface plasmon polaritons mayoffer a solution to realize compact photonic components. Over the recent yearsvarious types of SPPs photonic components have been widely investigated innanophotonics. In this paper, focusing on the properties of SPPs in nanostructures, wediscovered some novel phenomena and designed a series of nanoscale photoniccomponents by numerical simulation and theoretical analysis.With the development of processing technology, a lot of gradient-index materialshave been manufactured. As a key component of highly integrated opticalcommunication circuits, both the scale and the extinction ratio of the microresonant-cavities must be taken into account simultaneously. Therefore,we proposedand investigated a gradient index plasmonic ring resonator (Grin PRR). Because incomplex nanostructures numerical simulation based on finite element method(FEM)has the characteristics of flexibility and convenience, a2D FEM numerical simulationis developed and utilized to optimize the design parameters of Grin PRR in order toachieve an high extinction ratio and small size optical micro resonant cavity.Theoretical simulation reveals that the change of index gradient influences theresonant frequency, Q factor and the mode volume. Significantly, it is demonstratedthat the extinction ratio of Grin PRR can be optimized by varying the index gradientfor any radius. In conclusion，gradient index can enhance extinction ratio at certainsize, so this structure has both high extinction ratio and smaller size footprint. Thus,this high extinction ratio Grin PRR is a very promising high-density opticalintegration device, which may have promising applications in filter, high extinctionratio modulator and optical switching. We also proposed and investigated a waveguide device which has polarizationselectivity.We realized selective transit of different polarized light by puttingperiodically gold particles on both sides of the nanowires. The nanoscale waveguidedevices with simple structure and small size have potential application innanophotonics components, integrated nanophotonics circuit and bio-photonics.