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Research On Fiber Surface Plasmon Resonance Refractive Index Sensing

Posted on:2020-01-16Degree:MasterType:Thesis
Country:ChinaCandidate:M ZhangFull Text:PDF
GTID:2428330575953000Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
The fiber surface plasmon resonance(SPR)sensor uses the evanescent wave on the surface of the fiber to excite the free electrons on the metal surface to generate surface plasmon waves.By monitoring the change of the resonance absorption peak,the external refractive index is measured by the sensor.Optical fiber SPR sensors have received great attention due to their high sensitivity,small size,anti-electromagnetic interference and large-scale dynamic monitoring.It has been widely used in food testing,chemical analysis,biomedical and specific detection.In this paper,we focus on the theory and technology of plasmon resonance sensing on fiber surface,and carry out the following work:Firstly,the research significance and purpose of fiber SPR sensor are introduced.The research progress of fiber SPR sensor at home and abroad is summarized,and the structure and fabrication process of microfiber and side-polishing fiber are elaborated.The principle of surface plasmon resonance sensor is further explained by the theoretical study of total reflection,evanescent wave and plasma wave.The four excitation methods of the SPR sensor and the performance parameter of the evaluation sensor are described in detail.It provides the basis for the comprehensive design of fiber optic SPR sensors.Secondly,a microfiber SPR refractive index sensor coated with gold and silver film is proposed.The COMSOL software is used to optimize the parameters such as cladding diameter and metal thickness.A sensor model with a core diameter of 5.25 ?m,a cladding diameter of 7.25 ?m,and an Ag layer thickness of 45 nm is established.The simulation results show that the maximum response sensitivity of the sensor can reach 8523.33 nm/RIU at a refractive index of 1.33-1.40.Based on the above conclusions,10 layers of graphene are placed in the inner layer of the silver film.When the refractive index is 1.36-1.405,the maximum response sensitivity of the proposed sensor can reach 12723.10 nm/RIU.Finally,a D-type fiber SPR sensor with graphene coated silver nano-columns is proposed and simulated.The length of the sensing zone,the number of silver nano-columns,the diameter of the silver nano-columns and the air gap between the columns are optimized using COMSOL software.The simulation results show that the application of the graphene layer on the optimized structure can greatly improve the sensitivity of the sensor.When the diameter of the silver nano-column is 90 nm,the graphene is 23 layers,and the refractive index is changed in the range of 1.33-1.39,the maximum response sensitivity of the proposed sensor can reach 8860.93 nm/RIU.In summary,the application of graphene to optical fiber SPR sensors can improve the sensitivity of the sensor.With the deepening of research,further improving the sensitivity of the sensor and achieving specific selection will make the graphene-based SPR sensor have a wider application prospect.
Keywords/Search Tags:Microfiber, side-polishing fiber, surface plasmon resonance sensor, graphene, refractive index
PDF Full Text Request
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