Numerical Research On Plasmon Induced Transparency Effect Generated By The Resonant Coupling Of Multi Rectangular Cavity

Surface plasmon polaritons(SPPs)are the type of electromagnetic wave coupled to free electrons oscillation on the surface between the metal and the dielectric,propagating along the M-I interface and they have been considered as the most promising candidate for the realization of light manipulating at the subwavelength scales and highly integrated optical circuits based on the unique properties such as local field enhancement and overcoming the traditional diffraction limitation.In this paper,the transmission of SPPs wave in the structure consisted of MIM waveguide and resonators are studied in detail,and the realization conditions and physical mechanism of plasmon induced transparency effect(PIT)in this configuration are analyzed.The coupling process of surface plasmon polaritons in a MIM waveguide with a rectangular resonant resonator is investigated by numerical simulation and the modulation effects of the resonance occurred in the rectangular resonator on the transmission spectrum are analyzed numerically.The results show that the main waveguide is coupled with the resonator by evanescent field energy,and when the electromagnetic energy in the resonator satisfies the F-P like resonant condition,the SPP energy will be enhanced in the resonator,and the energy in the main waveguide will be reduced significantly.Based on the narrowband effect of F-P resonance,this structure can provide valuable reference for the realization of Nano-scale narrowband filters.The parallel double resonators are introduced on the same side and both sides of the waveguide.The plasmon induced transparency(PIT)phenomena in these two structures are analyzed respectively,and the anomalous transmission peaks in the absorption region are obtained.Based on the mode field distribution,the mode splitting effect is employed to explain the coupling phenomenon between the parallel double resonators and the main waveguide.The results demonstrate that when the parallel resonators are close enough,the two super resonant modes are generated in the double resonators and the interval of two center wavelengths corresponding to the two super modes will decrease as the spatial spacing of double resonators increases.As a result,the anomalous transparency window will be achieved in the region between the two resonant wavelengths.The three and four parallel resonators have been introduced on both sides of the waveguide,two and three transmission peaks in the transmission spectrum of the waveguide have been obtained by numerical simulation.The effects of different resonator lengths and coupling distances on the intensity,location and bandwidth of multiple transmission peaks have been studied in detail.Based on the resonant effect and mode splitting principle,the formation and evolution of multiple transmission peaks are explained.Successively,a single two dimensional waveguide filter model is designed based on the combination of double parallel resonators and the four resonators configurations.The conclusions of this paper lay the foundation for the further realization of multi wavelength narrow band filtering and high sensitivity sensing.