The Research Of High-sensitivity Surface Plasmon Resonance Refractive Sensor Based On Graphene And Topological Insulator

In some recent years,surface plasmon polaritons?SPPs?has attracted great attention with the development of nanotechnology and integrated photonics.And one of the important applications is surface plasmon resonance?SPR?sensor.According to its outstanding advantages?real-time analysis,high sensitivity,high stability,etc.?,it has been widely used in various industries such as chemistry,environmental monitoring,food safety,biological analysis and other fields.However,the traditional SPR sensor based on precious metal is limited in detection sensitivity and can't excite SPPs in terahertz and mid-infrared band.Therefore,it has been the focus of researchers that search new materials which can enhance the sensitivity of SPR sensors and effectively excite SPPs at long wavelengths.The commonly methods to increase sensitivity are structural and material designing.The design of structural is mainly realizing the coupling between different modes.and the addition of new materials to enhance the sensitivity of SPR has been greatly developed.With the discovery and research of two-dimensional materials such as graphene,black phosphorus,transition metal dichalcogenides?TMDCs?and so on,the development of SPR sensing is full of prospects.In this paper,we design a new method to enhance the sensitivity of SPR sensor based on the effect of two-dimensional material.We have designed three kinds of SPR sensor chips by employing different structure and introducing new two-dimensional materials.the design results are as follows:?1?In terahertz band,an Otto structure gas sensor based on graphene band is designed.by optimizing the structure parameters,the angular sensitivity of?the maximum sensitivity?147°/RIU can be obtained.The sensitivity of the terahertz gas sensor based on graphene is three to four times higher than that of the related terahertz gas sensor.The relevant research papers are published in IEEE Photonics Journal.?2?We designed a hybrid structure for the SPR sensor based on strong coupling In terahertz band,which is composed of surface phonon polaritons?SPhPs?and surface plasmon mode.The single SPhPs mode based on cesium iodide?CsI?and the SPP mode based on graphene can excite in THz band,but the sensitivity of the two modes is low,and the high sensitivity of954RIU^-1 can be obtained by the method of strong coupling,which is ten times higher than that of single mode excitation,and a large quality factor of 74740 RIU^-11 has been obtained.The results are published in IEEE Photonics Journal.?3?We have designed a SPR sensor based on two-dimensional topological insulator bismuth selenide?Bi₂Se₃?to enhance the surface sensitivity.The morphology and size of Bi₂Se₃can be adjusted by different reaction conditions,so it has excellent properties in thermoelectric and electronic band structure.and has some advantages over the two-dimensional materials such as graphene and black phosphorus in the aspect of variation of vertical thickness.In this design,high quality Bi₂Se₃ nanocrystals were prepared by hydrothermal method,we prepare different thickness of Bi₂Se₃ thin films by spin-coating.The higher sensitivity?2929.1 nm/RIU?and quality factor(33.45 RIU^-1)was measured by experiment,and the Bi₂Se₃ nanosheets has been three times spin-coating on the interface of gold film.Compared to the traditional SPR sensor based on gold,the sensitivity was increased by 51.97%.The results have been submitted on ACS omega.