Study On Propagation Characteristics Of Lossless Surface Plasmon Polariton Solitons In Slot Waveguide

When the size of conventional optical circuits is reduced to the nanoscale,the propagation of light is limited by diffraction.However,surface plasmon polaritons(SPPs)provide a way to build such nanoscale photonics devices.plasmonic waveguides can limit and manipulate surface polarons at the nanoscale and support the propagation of surface polariton at their metal-dielectric interface.among them metal-dielectric-metal(MDM)waveguide are considered because of their simple structure,easy fabrication,strong ability to limit light waves,so they are considered that it is one of the most valuable micro-nano optical structures.However,because of its metal interface,SPPs will inevitably receive ohmic losses when they propagate on the interface,which greatly limits their propagation distance,which becomes one of the bottlenecks restricting the practical application of metal micro-nano waveguides.So the main purpose of this dissertation is to enable SPPs to overcome ohmic losses,and to fully combine the advantages of SPPs with MDM waveguide structures to enable SPPs to travel longer distances and to make it more valuable.The research in this article focuses on the following aspect:(1)The electric field modes and dispersion relations in MDM waveguides were studied.We first introduce the MDM waveguide structure,and derive its dispersion relationship through Maxwell's equations,and prove that the TM mode can excite SPPs.Then by analyzing the electric field mode of the MDM waveguide,it is found that the antisymmetric mode in the TM mode with the increase of the propagation distance,the intensity of the light field is more severe than that of the symmetric mode,not as far as the symmetric mode.So in the following research we can provide gain for the system so that both symmetric and antisymmetric modes can propagate the ideal distance.(2)The introduction of incoherent pumping is used to study symmetric and antisymmetric SPPs solitons in MDM waveguides.We propose a scheme that doping three-level quantum emitters to produce electromagnetic induction transparency(EIT),and introducing incoherent pumps to provide gain to the system and offset ohmic losses to achieve a lossless SPPs solitons.we first study the relationship between incoherent pumping rate ?31 and the active gain-Im(K)and find that the gain for both modes increases with increasing ?31,and that the gain does not increase once the absorption saturates for antisymmetric mode.By calculating the group velocity,we find that both modes can propagate as slow light.In the nonlinear propagation regime,it is found that although different modes employ different incoherent pumps,both symmetric and asymmetric SPPs can greatly enhance Kerr nonlinearity under the combined action of the EIT effect and the enhanced trapping effect of the MDM waveguide light field.Finally,through numerical simulation,it is proved that gain-assisted(1 + 1)dimensional symmetry and antisymmetric SPPs solitons can be realized by the optical field trapping effect of MDM waveguide.The research results in this paper can help us understand the propagation characteristics of surface plasmon solitons,and their prediction results have certain guiding significance in the study of nano-scale optical transmission.