Research On Transmission Characteristics Of Plasmon Waveguide And Its Application In Sensors

The surface plasmon polaritons is a kind of evanescent wave with sub-wavelength binding characteristics.It propagates along the metal-insulator surface.It can not only break through the diffraction limit of light,but also has the characteristics of being sensitive to the surrounding environment and the dielectric parameters of the structure.Therefore,it is widely used in sub-wavelength miniature optoelectronic sensors.Because of its simple structure and easy integration,the metal-insulator-metal(MIM)structure shows good application prospects in sub-wavelength optical devices based on SPPs design.The continuous bright state is affected by the discrete dark state to form the Fano resonance.Compared with the traditional Lorentz peak,the Fano peak can not only enhance the field,but also produce sharp resonance peaks and asymmetric transmission lines.Therefore,the metal-insulator-metal structure sensor based on the Fano resonance design has the advantages of simple structure and reliable detection results,and this design has become a hot spot in the field of micro-nano optical device.However,this sensor always has the problems of low sensing sensitivity and non-adjustable transmission peak dynamics after processing.Focusing on these two issues,the following work is mainly carried out:1.A dual-purpose sensor with ethanol-sealed octagonal ring cavity MIM waveguide is designed.The calculation results of finite element method numerical simulation and multimode interference coupled mode theory are compared.The feasibility of ethanol as a heat-sensitive filling material is also analyzed.The sensitivity of the temperature sensor is 0.9nm/?,and the sensitivity of the refractive index sensor is 2400nm/RIU.2.Changes in parameters can cause red or blue shifts of the transmission peaks,but the previous explanations are either deviation.In previous studies,the real part of the effective refractive index(Rneff)at different incident wavelengths was usually simplified as a constant.In the study of the MIM and graphene hybrid cavity coupling plasmonic resonator system,Rneff is regarded as a variable to ensure that it is an precise value when calculating the resonance wavelength.The ring resonance theory is used to explain why the transmission peak appears red shift with the increase of rb.3.A dynamic adjustable MIM and graphene hybrid cavity refractive index sensor is proposed,which introduces a graphene nanotube into the resonant cavity to cause plasmon resonance in the graphene nanotube,thereby generating Fano resonance in the transmission spectrum.By applying electric field to change the properties of graphene nanotubes,the Fano peak can be adjusted dynamically,which solves the problem that the working characteristics of MIM structure sensor remain unchanged after processing.