Research On Fiber Surface Plasmon Resonance Sensor Based On MSM Structure

Compared with the traditional electronic sensor,the optical fiber sensor has a lot of virtues,for example high precision,small volume,corrosion resistance,anti electromagnetic and radiation interference.Based on the o1 ptical fiber sensing technology,the optical fiber Surface Plasmon Resonance(SPR)sensor technology,after years of improvement and research,has a wide range of applications in biomedicine,environmental surveying and other realms.At the moment,some main structures in the research field of optical fiber SPR sensor,such as side polishing structure,melting cone structure and bending structure,have the disadvantages of complex processing technology,high manufacturing cost and low mechanical strength of structure.Therefore,based on the previous research,this paper proposes an optical fiber surface plasmon resonance sensor based on Multimode Singlemode Multimode(MSM)structure.Firstly,based on the theory of multilayer reflection and optical fiber transmission,the formula of the total reflection coefficient of the optical fiber SPR sensor is calculated,and the influence of the structural parameters of the sensor on the performance of the sensor is analyzed theoretically.Then,the influence of different metal film materials,thickness of metal film and length of single-mode fiber on the performance of the sensor is analyzed by FDTD simulation,and the optimal parameters of the sensor performance are obtained.Based on these parameters,the sensitivity of the optical fiber SPR sensor with MSM structure is about 6875 nm/RIU.Based on the difference of resonance wavelength of different metal film materials,a dual channel MSM structure fiber SPR sensor is proposed and designed,which can select different sensing channels according to the different range of environmental refractive index to be measured,greatly improving the performance of the sensor.The optical fiber SPR sensor with MSM structure was fabricated by the technology of optical fiber fusion and magnetron sputtering.The sensor test system was designed and built.The change of the external environment refractive index was simulated by the glycerine solution of different concentration.The transmission spectrum of the sensor under differentenvironment refractive index was measured.The average sensitivity of the optical fiber SPR sensor was about 1118 nm/RIU.The experimental results show that the optical fiber SPR sensor designed in this paper can accurately measure the refractive index,which lays a foundation for further research and development of the optical fiber SPR sensor.