Research On Fiber SPR Refractive Index Sensor Based On Composite Materials

The fiber sensor based on surface plasmon resonance(SPR)technology is a clever combination of SPR technology and fiber,which not only makes the sensor small and sensitive.In addition,the sensor has the advantages of large-scale monitoring capability and strong electromagnetic interference resistance.Therefore,it is widely used in the fields of biomedicine,chemical analysis,environmental monitoring and food detection.Because the D-shaped fiber has flat surface and asymmetric structure,it can be better combined with SPR technology.At the same time,the combination of some metal and oxide materials can enhance the capability of SPR sensors.Therefore,several D-shaped fiber SPR refractive index(RI)sensors based on composite materials are designed and studied in this paper,in order to enhance the RI sensitivity(RIS)and FOM capability of fiber SPR sensors.The following work has been carried out:1.A D-shaped fiber SPR sensor based on Au nanowires array is designed.The structural model is established by COMSOL software for birefringence theoretical analysis.It is found that the Au nanowires sensor can excite LSPR both perpendicular and parallel to the polished surface,which is different from that when using metal film.The sensing capability of the sensor and the optimized parameters of nanowires were studied.The results show that the maximum RIS of the resonant peak of the sensor in y-polarized mode is 3421 nm/RIU,and the maximum FOM is 190 RIU^-1;In x-polarized mode,the maximum RIS is up to 1823 nm/RIU,and the maximum FOM is up to 200 RIU^-1.2.A D-shaped fiber SPR sensor based on Au nanowires-Ti O₂structure is designed by using Ti O₂nano-materials.The results show that after adding Ti O₂film,the number of resonance peaks increases,multi-wavelength detection can be realized,and the range of RI can be expanded;The maximum RIS is 2837 nm/RIU at the external RI of 1.37,the average RIS is 2142 nm/RIU,and the maximum FOM can reach 127 RIU^-1at 1.31.3.A D-shaped fiber SPR sensor based on Au nanowires-Zn O-Ti O₂structure is designed by using Zn O nano-film.The results show that the measurable RI range of the sensor is large,and the RIS is significantly enhanced:the maximum RIS can reach14788 nm/RIU when the external RI is 1.41,the average RIS is 7877 nm/RIU.And the maximum FOM can reach 175 RIU^-1when the external RI is 1.36.4.A D-shaped fiber SPR sensor with Au nanowires-Zn O structure is designed.The results indicate that the sensor can sense in a wider outside RI range.The maximum RIS can reach 24127 nm/RIU when the RI is 1.43,the average RIS is13234 nm/RIU,and the maximum FOM can reach 217 RIU^-1when the RI is 1.37.