Study On Structure Design And Characteristics Of PCF Based SPR Sensor

Photonic crystal fiber?PCF?based surface plasmon resonance?SPR?sensing technology combines the advantages of SPR with high sensitivity and PCF with flexible structure design.It can accurately control the evanescent field and light propagation properties in single or multimode configurations to solve the problem of hard phase match existing in traditional SPR sensors.These excellent characteristics afford it to possess broad development prospects and essential application values in the optical sensing area.This thesis focuses on the PCF-SPR's applications in the aspects of refractive index?RI?detection and temperature sensing.We design three different sensing structures,whose sensing properties are investigated based on finite element method?FEM?,and obtain the following results:?1?A PCF-SPR sensor based on square array air holes is proposed.Different from traditional hexagon structure,four large air holes in a square array are introduced to form the single layer cladding and enhance the sensitivity by allowing easier coupling between the fundamental and the plasmonic mode.The gold is used as the only plasmonic material to reduce the difficulty in deposition.The guiding properties and the effects of the parameters on the sensing performance are investigated in detail.According to the numerical results,the proposed sensor has significant advantages of high sensitivity of 7250nm/RIU within the detection RI range of 1.38-1.42 and high resolution of 1.0638×10^-5RIU respectively.?2?A PCF-SPR sensor based on high birefringence is proposed.The birefringence induced by different sizes of air holes in the cladding helps in coupling more light into a particular direction to achieve easier coupling and high sensitivity.The metal film and the analyte channel are placed outside the core area to reduce the difficulty in fabrication.By optimizing the structure,the proposed sensor can obtain the average wavelength sensitivity of 15180nm/RIU and high linearity with the RI detection range of 1.40-1.43,corresponding to the resolution of 5.6818×10^-6RIU.?3?A dual-core PCF-SPR temperature sensor is presented.The central air hole is selected in order for the inner wall to be deposited with gold,and filled with temperature sensitive liquid with a high-value thermo-optic coefficient to realize temperature sensing.The effects of temperature on the background material's RI,the metal's dielectric constant and the metal film's thickness are taken into consideration to ensure the accuracy of the sensor.The numerical results show that the temperature sensor can realize maximum average temperature sensitivity of-9.793nm/°C with the detection range of 0°C-30°C,corresponding to the resolution of 5.6818×10^-6°C.All PCF-SPR sensors presented above have great advantages of high sensitivity and resolution.Hence,they are very competitive in biochemical,biological analyte detection and temperature sensing.