Research On The Surface Plasmon Polariton Refractive Index Sensor On Fiber End Surface

Surface plasmon resonance(SPR)fiber sensing technology is a new method to achieve optical transmission,coupling,resonance,amplification and detection on the micro-nano scale combined with plasma optics and fiber optics.It can effectively overcome the bottleneck of traditional fiber sensing.problem.The SPR refractive index sensor based on the fiber end-face sub-wavelength aperture array structure is very sensitive to refractive index changes,and is a key device for quantitative analysis and label-free real-time detection of chemical reactions and biological interactions,and is also the core of future sensor research.Most of the existing research is based on single resonance wavelength for sensing analysis,but based on multiple resonant wavelength sensing analysis is rarely reported.Therefore,this thesis mainly studies the H-shaped gold slit array structure and the asymmetric split-ring array structure with dual resonance wavelength characteristics.The main research results are as follows:1.A new structure of asymmetric splitting nanorings is proposed.Among them,the asymmetric Fabry-Perot cavity composed of two asymmetric rings will further enhance the effect of SPP on EOT,thus exciting two resonance transmission peaks.At the same time,the refractive index sensing characteristic will be studied based on the double resonance transmission phenomenon.The influence of the angle and radius of the splitting ring and the thickness of the gold film on the phenomenon of double transmission peaks in the structure is studied by using the finite difference time domain(FDTD)numerical simulation method.It is found that the wavelength of the double transmission peaks can be effectively regulated by the above main parameters.When the left tension angle is 90 degrees,the right tension angle is 180 degrees,the outer radius is 100 nm,the inner radius is 40 nm,and the thickness of the gold film is 30 nm,the structure has good double transmission peaks.Its sensitivity is 117 nm/RIU and 285 nm/RIU,respectively.2.A new structure based on H-shaped metal slits is proposed.Among them,the Fabry-Perot cavity formed by the H-shaped slit will further enhance the effect of SPP on EOT,thereby exciting two resonance reflection dips;and studying the refractive index sensing characteristics based on the double resonance reflection phenomenon.The influence of slit length,width and thickness of gold film on the double resonance reflection phenomenon is studied by using finite difference time domain(FDTD)numerical simulation method.It is found that the wavelength of double resonance dip can be effectively controlled by the above main parameters.When the length of vertical slit is 150 nm,the length of horizontal slit is 200 nm,the width of slit is 50 nm,and the thickness of gold film is 300 nm,the structure has good double resonance reflection phenomena.Its sensitivity is 590 nm/RIU and 1199 nm/RIU,respectively.3.The fiber-optic end-face nanostructure preparation scheme based on silicon template transfer technology was preliminarily proposed,in order to realize the structure proposed in this paper by using the low cost,short cycle and high feasibility of the method.