Dual-core D-type Photonic Crystal Fiber Refractive Index Sensor Based On Grid Coating

With the development of Internet of things technology,sensors are developing towards the direction of accuracy,sensitivity and intelligence.Optical fiber sensor is favored by its excellent performance,such as medicine,biology and environmental quality detection and so on.With its unique optical properties and flexible microstructure design,photonic crystal fiber?PCF?has injected new vitality into the fiber sensor family.Surface plasmon resonance?SPR?sensing technology provides a new choice for the research of high sensitivity refractive index sensor.The combination of photonic crystal fiber and surface plasmon resonance to carry out the research of new structure PCF-SPR sensor has important academic significance and wide application prospects.In this thesis,a new structure of dual core D-type PCF-SPR refractive index sensor is designed.The dual core structure and grid coating are used in the polishing plane of the fiber,which can strictly control the thickness of the metal film.The gold grid is introduced to adjust the resonance wavelength of the sensor,which greatly improves the refractive index sensitivity.Under the anisotropic perfectly matched layer boundary condition,the cladding air diameter,center air diameter,polishing depth,gold grid thickness and duty cycle of D-type PCF are analyzed and optimized by full-vector finite element method.Under the optimal structure of the sensor,the maximum theoretical resolution of the refractive index sensor is 1.28×10^-5 RIU in the refractive index range of 1.26 to 1.30.When the linear coefficient of is 0.99653,the average sensitivity can reach 7130 nm?RIU^-1.Due to the limited detection range of the refractive index of the D-type PCF-SPR sensor with gold grid film,a D-type PCF-SPR refractive index sensor based on copper grid film is proposed in this thesis.Under the optimal structure of the sensor,the detection range of refractive index of the sensor is from 1.31 to 1.35,and the linear coefficient is 0.99787.The average sensitivity can reach 8900 nm?RIU^-1,and the resolution can reach 1.04×10^-5 RIU.The D-type PCF-SPR refractive index sensor designed in this thesis has the advantages of simple fabrication process,wide refractive index detection range and high average sensitivity.The combination of the two sensors can detect analytes with refractive index range of 1.26 to 1.35,which can be widely used in biological,pharmaceutical and environmental quality detection fields.