Controllable Transmission And Emission Of Surface Plasmon Polaritons From Wire To On-chip

The optical fibre technology has laid a solid foundation to the development of the optical communication.As a unique optical waveguide,the optical signal can propagate in the optical fibre with a high speed.With the development of the nanotechnology,it is important to minimize the size of the optical waveguide into the nano or micro scale due to the pressing needs from the optical integrated chip of the waveguide.The traditional dielectric waveguide,however,cannot confine the light into a subwavelength scale due of the limitations of traditional optical diffraction limits.The noble metal micro/nano structure can be excited by the incident light,where the photon and free electron can couple with each other and form a new wavelike electromagnetic mode which is call surface plasmon.Moreover,when the wavevector of the incident light matches with the wavevector of surface plasmon,the surface plasmon can propagate on the interface of the metal-dielectric,which is called surface plasmon polariton(SPP).As the name implies,SPP is an electromagnetic wave like fashion propagates alone the interface between the interface of dielectric and metal,which can confine the light on the vicinity of the dielectric-metal interface.Plasmonic waveguide is a waveguide which can support SPP propagate on the surface of the waveguide.Compared with the silica based traditional dielectric waveguide,plasmonic waveguide can confine the light into nanoscale region,which largely reduces the space between the components.Up to now,two kinds of plasmonic waveguides have been widely used.One is the one-dimensional waveguide such as nanowire or nano strip,which has a grate unidirectional propagation property.Another one is plannar waveguide such as waveguide array or plate like waveguide,which shows a good performance on wide-range propagation and emission of SPP.Both of the waveguides show a great potential in new generation photonic device.However,there are still some limitations of the plasmonic waveguides,such as the large ohmic loss caused by the metal and SPP propagation regulation on the wave guide.Therefore,a plasmonic waveguide with ultrasmooth surface and tunable multi propagation-channel is urgently needed for developing plasmonic devices.In this work,monocrystalline silver nanowire and triangular microplate with atomic smooth surface are synthesized with a simple and rapid wet chemical method.Corresponding SPP excitation and propagation process are investigated through far-field and near-field distributions both experimentally and numerically.The propagation path and direction,emission range and intensity of the SPP can be controlled by changing the excitation conditions and introducing the tip enhanced system on the silver nanowire and micro triangle plate.The detailed works including two main parts:?.Tip controlled surface plasmon polariton on silver nanowire:Based on the silver nanowire plasmonic waveguide,the SPP propagate on the surface of the waveguide can be tuned via changing the properties of the excitation light and introducing the silver tip.The electromagnetic simulations are done with the FEM method,which can help us to understand the intrinsic mechanism of the SPP propagation.The results show that the monocrystalline silver nanowire shows a great unidirectional propagation and strong confinement of the light.The chiral SPP propagation can be achieved via changing the polarization state of the excitation light.Moreover,introducing the silver tip can control the emission of the SPP.?.Controlled multichannel SPP transmission on atomic smooth silver triangular waveguide:An atomic smooth triangular waveguide with controllable multichannel transmission and relative long 1/e decay length is demonstrated.Corresponding SPPs excitation and propagation process are investigated through far-field and near-field distributions both experimentally and numerically.It is found that two different SPPs propagation modes can be selectively excited and supported on the surface of the 2D waveguide,and the propagation path can be controlled by the interference of the SPPs modes.The collimated beams with tunable period are also achieved on this waveguide via utilizing the interference between the reflected SPPs and the SPPs propagating from the other side of the plate through the edge.This work provides high performance of the plannar plasmonic waveguides with a comprehensive analysis of surface plasmon,which may have potential applications in microplate based integrated photonic devices.