| The application research of Surface Plasmon Resonance has particularly prominent significance in the fields of biology,chemistry,materials,and medicine.Among them,the related research of SPR sensor has always been a hot spot in this research field.In recent years,with the development of advanced nanomanufacturing technology,SPR sensors based on metal nanostructures have received widespread attention due to their great application value in label-free biosensing.The focus of sensor application research is how to improve the sensing performance of the sensor.This paper optimizes the design of the metal nanostructure array to excite different SPR modes,and uses the coupling and resonance of different SPR modes to improve the sensing performance of the SPR sensor.In particular by the design of different metallic nanostructures in different bands,exciting Localized Surface Plasmon Resonance,and the combined effect of the grating structure on the metal thin film array,the excitation along the metal / dielectric interface Surface Plasmon Polariton,through comprehensive adjustment of nanostructure geometric parameters and array period,so that two SPR modes can be coupled;or by designing binary metal nanostructures to promote different metal nanostructures The superposition resonance of different SPR modes is generated between the structures.These different forms of interaction mechanism SPR mode,a substantial increase in the quality factor of different types of sensors,which have great significance in guiding the design and development of high-performance SPR sensor.Firstly,the basic theory of SPR is discussed.Localized surface plasmon and surface plasmon are introduced respectively,and the research status of surface plasmon resonance in refractive index sensing and temperature sensing is briefly discussed.Secondly,the numerical calculation methods and experimental preparation methods of SPR sensors with binary metal nanostructures are introduced.Finally,this paper innovatively proposes three design schemes for surface plasmon resonance sensors based on binary metal nanostructure arrays.The content of the paper mainly includes the following three aspects:1.A surface plasmon resonance fiber sensor based on the elliptical nanohole nano disk binary array is presented.The sensor superimposes the nano disk and the nano elliptical hole structure on the end of the fiber to construct a new type of metal nanobinary structure array to produce surface plasmon resonance.The array produces three optical resonance modes in the near infrared light range under normal incidence.These modes not only meet the characteristics of narrow band,but also have the advantages of high peak contrast.When the external environment is in the refractive index range of 1.33-1.40,the Dip A has obtained high refractive index sensitivity of 669 nm/RIU,and the half height and width are 5.9nm,and FOM of 106.1 is obtained in the refractive index range.This is 5.5 times higher than the nano-ellipse single structure array.In addition,this nested binary array structure has strong polarization-dependent reflection spectrum characteristics.Based on these characteristics,this SPR sensor structure can be used to develop biosensors and optical polarization devices with good performance,and has application prospects in biological detection and medical diagnosis.2.A surface plasmon resonance sensor with ultra-narrow resonance spectral linewidth based on binary right triangle nanoarray is proposed.The SPR sensor is composed of a pair of right-angle triangle gold nanoblock binary structure arrays arranged on the surface of the gold film in a certain period.When the incident light is perpendicular to the normal incident,the reflection spectrum of the binary system array film produces two resonant absorption Dips A and B at 916 nm and 929 nm with linewidths only a few nanometers.According to the analysis of the electric field distribution of the structure array at the position of the resonance absorption peak,the ultra-narrow linewidth resonance absorption spectrum benefits from the superimposed resonance enhancement of different SPR modes.At the same time,the stimulated SPR mode is locally enhanced on the surface of the gold film and around the nanostructure,which has a stronger field intensity and a larger penetration depth,so the resonance absorption peak shows a higher refractive index sensitivity.The results show that the refractive index sensitivity of Dips A and B is up to 679 nm/RIU and 682nm/RIU,respectively.In addition,due to the narrow-spectrum characteristics of the resonance mode,the FOM of Dips A and B is as high as 459 and 182 in the wide refractive index range of 1.3～1.375.Moreover,the designed structure shows very good linearity over a wide refractive index range.These parameters indicate that the binary right triangle nanoarray structure sensor has great potential to be applied in the production of high-performance biochemical detection platform.3.A surface plasmon resonance fiber probe temperature sensor based on cross structure metal nanoarray is presented.In this paper,a periodic array of cross-shaped metal nanostructures which can generate surface plasiton resonance is constructed on the optical fiber end face.Then,polydimethylsiloxane(PDMS),a material with high thermal and optical coefficient,is encapsulated on the optical fiber end with a capillary glass tube to make it a complete optical fiber temperature sensor.This cross-shaped metal nanoarray produces SPR resonance mode in the near-infrared light range.This resonance is due to the strong coupling between the local surface plasmon LSP mode and the surface plasmon SPP mode to produce Fano resonance,has a very narrow spectral line width.At the same time,the resonance field excited by this resonance mode is distributed around the metal metal nanostructure and the upper surface,so the sensor has high sensitivity,coupled with the high thermo-optic coefficient of PDMS,the sensor achieves-0.31 in the range of 20 ℃～60 ℃The high temperature sensitivity of nm/℃ and the quality factor FOM is also as high as0.127,which exceeds most other types of optical fiber temperature sensors.Therefore,the proposed temperature sensor has potential application prospects in many fields such as biomedical diagnosis and environmental monitoring. |
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