Design Of Side Polished Fiber SPR Sensor Based On Nano Gold Structures

SPR sensors manufactured by side polished fiber were widely used in biomedical, physical detection, environmental pollution due to its high sensitivity, good integration, and can realize long distance online real time observation easily. It regarded the side polished fiber as the guided wave carrier, and excited surface plasmon resonance(SPR) by the evanescent field in the polished region of a side polished fiber. However, there were a lot of factors that influenced the performance of a side polished fiber SPR sensor, such as the length of polish, residual fiber thickness, metal film thickness and the structure of the metal. The study about the influence of these factors not only can improve the performance of a SPR sensor but also can give a scheme for the design of a new sensor structure. Therefore, the status and existing problems were summarized firstly. Then the system research included types and parameters of side polished fiber, the structure and parameters of metal film were given, and the optimum design were proposed. This paper was divided into five parts:Firstly, this paper proposed the development course, the basic concepts of SPR sensor and the fiber SPR sensor. Summarized fiber SPR sensors based on side polished fiber and the existing problems of it. Then put forward the main research contents of this paper.Secondly, this paper introduced several kinds of analytic method and numerical simulation method about fiber SPR sensor, mainly talked about the finite element method(FEM) which was chose in this paper. Then, described the steps of modeling and the parameter settings in the simulation software COMSOL Multiphysics. Finally, discussed the refractive index dispersion relations of gold and did some preparation for the subsequent simulation.Thirdly, researched the influence of fiber mode, gold film thickness, residual fiber thickness on the performance of the side polished fiber SPR sensors, and obtained the optimum parameters. And compared results of the theory analysis with the performance of experiment did before.Fourthly, designed and optimized three kinds of side polished fiber SPR sensor based on circular gold nano-rod array, square gold nano-rod array, and triangular gold nano-rod array to obtain the optimum parameters, respectively. It turned out that the nano-rod array can help the side polished fiber SPR sensor to have a higher sensitivity. The study found that the side polished fiber SPR sensor based on gold nano-rod array can improve the sensitivity.Fifthly, compendiously summarized all of the work in this paper, and pointed out the shortage, then offered a proposal of it.The innovation of this paper lies in:Firstly, a new structure of the side polished fiber SPR sensor based on gold nano-rod array was given in this paper, this new structure simulated can improve the sensitivity of a SPR sensor.Secondly, the structure of side polished fiber SPR sensor based on triangular gold nano-rod array was proposed and built, it not only can improve the sensitivity, high linearity but also can get a large measuring dynamic range. Therefore, there is great research significance and practical value of simulating the fiber SPR sensor.