| Optical fiber sensor has the advantages of miniaturization,light weight,anti electromagnetic interference,low cost and real-time on-line detection.These advantages make optical fiber sensor applied in food safety,physical quantity detection,chemical quantity detection,biomass detection,aerospace and military equipment.Surface plasmon resonance sensor has unique advantages in the field of biological detection,and the improvement of SPR sensor performance can provide a powerful tool for medical biological detection.In biological detection,the sensor response speed is fast and biological molecules can be detected without labeling.Based on this,in order to improve the performance of SPR sensor,the main research contents are as follows:(1)Firstly,the current research status of optical fiber SPR sensor is introduced.According to the current development and research status,several methods to enhance the sensitivity of SPR sensor are summarized,including adding materials,transforming structure and combining other new technologies to improve the sensing performance.(2)Based on the theory of attenuated total reflection,the concepts of surface plasma wave and evanescent wave are introduced,and the generation conditions of SPR phenomenon and the sensing mechanism of optical fiber SPR sensor are studied.The finite element model of optical fiber SPR sensor is described and constructed in detail,and the multi-layer reflection matrix method is introduced for sensor analysis.Based on the local electric field in the sensing area,the essence of improving the sensitivity of the sensor is studied.(3)The structure parameters of the sensor are optimized by the finite element method and the transmission matrix method.The optimal parameters are the thickness of 50nm gold film and the length of 10mm sensing area.The mechanism of sensor resonance and the essence of sensor are studied by software simulation.Then through the experiment,we made the coreless fiber and single-mode fiber SPR sensor,and built the experimental system to test the refractive index.The sensitivity,half peak width and quality factor of the two sensors are obtained by experiments.Through the comparative analysis of the two sensors,the sensitivity of the two sensors is not much different.The half peak width of the resonance spectrum of the coreless fiber as the sensing area is narrower,so it has more advantages in the sensing.(4)The coupling enhancement mechanism is introduced,and an optical fiber SPR sensor based on gold film and Au nanoshell is proposed.The sensor has smaller half peak width and higher quality factor.The effect of hollow Au nanoshell with different ratio of inner diameter to outer diameter on the coupling effect of gold film was studied by finite element method.The simulation results show that the coupling effect between SPR on the surface of gold film and LSPR on the surface of gold nano shell can effectively improve the electric field intensity in the sensing area.The refractive index sensing experiment shows that the sensitivity of optical fiber/gold film/Au nanoshell(AuNS(50/40))SPR sensor is 3054nm/RIU,which is 945nm/RIU higher than that of optical fiber/gold film SPR sensor.(5)Based on the finite element method,the enhancement of electric field by the coupling between SPR of gold film and LSPR of Au nano biconical particles on the surface of coreless fiber is analyzed.The experimental results show that the Au nano biconical particles can improve the sensitivity.The sensitivity of the improved Au nano biconical particle sensor is 3514nm/RIU,which is 64%higher than that of the traditional gold film SPR sensor,and the quality factor is 24%higher.(6)An optical fiber/gold film/BaTiO3 thin film SPR sensor is proposed.The sensitivity was improved by the charge transfer between the gold film and BaTiO3 film.The sensitivity of the sensor was 4700nm/RIU when the thickness of the film was 50nm.The finite element simulation results show that BaTiO3(l0nm thickness)can improve the electric field intensity in the sensitive region.The results of refractive index experiments show that the sensitivity of the sensor coated with 10nm BaTiO3 film is 2543nm/RIU,495nm/RIU higher than that of the traditional gold film SPR sensor.In the range of high refractive index,the sensitivity of the sensor can reach 6040nm/RIU.In this paper,several kinds of sensors with good performance are proposed based on the introduction of the research status of optical fiber SPR sensor and the summary of the methods of enhancing sensitivity.The proposed sensor has broad application prospects in the field of biosensor and low concentration biomass detection. |
PDF Full Text Request